5 '^. ■^' .O^y^^t?^-'. ^ .•■ft * ,- >- ^" C * „ . , ';<■ -^ (^'b .-t' 3 0^ ^■^. -,"^^ ^ :i: c^^\^^i.'^*^b:'-" ^^c ;- '?^ J .6' l"?-' V ,^^^ '/^ ^ A"* .0^ V * o ^ V ■>*, \ s * * /■ ,0 a x^^^. * .'\ -->. A"** ^^ ^y - ■i'. -<■ V. a\ .on^c -^^ __•^^f •^ •-> -^oo A u V ""^Va' A-^- A «, ^ . -'^ ' ' .-^^ cP- \ 1 s <. do^ .^^ .s^-^, ^<-%^ .A^^ ^^. A -V 4 • ,0- • O cP\^' ..•■^^ .•iv^ c« -^oo \^^ , ^^ * .. . > .^0 "X \o,- •> ^^/- v^' ^^°<. 'V\X '^ *.'%^^.^^ X ''^ o 'o > ■^ ^.''/T'T^^ "^^ v^^ Oo, = 00''' .-.H -7-, C- 1 ^ " x^^ .x"^-' '>. * ., ,0- ^^.v^ .V> MANUAL OF VEGETABLE-GARDEN INSECTS Ube IRural /iDauuals Edited by L. II. BAILEY Manual of Gardening — Bailey Manual of Farm Animals — Harper Farm and Garden Rule-Book — Bailey Manual of Fruit Insects — Slingerland and Crosby Manual of Weeds — Georgia The Pruning-Manual — Bailey Manual of Fruit Diseases — Hesler and Whetzel Manual of Milk Products — Stocking Manual of Vegetable-Garden Insects — Crosby and Leonard Manual of Tree Diseases — Rani in Manual of Home-Making — Van Rensselaer, Rose, and Canon MANUAL OF VEGETABLE-GARDEN INSECTS BY CYRUS RICHARD ^ROSBY AND MORTIMER DEMAREST LEONARD OF THE NEW YORK STATE COLLEGE OF AGRICULTURE AT CORNELL UNIVERSITY THE MACMILLAN COMPANY 1918 All riglitt) resei^ved COPTEIQHT, 1918, bt the macmillan company. Set up and electrotyped. Published September, igi8. J. S. Gushing Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. 'CI.Af)0H209 Co JAMES FLETCHER STUDENT AND TEACHER FOR A (ilAiriKK OF A CENTIHY ENTOMOLOGIST AND 150TANIST TO TIIK DOMINION OF CANADA, NOTED FOK HIS STUDIES IN ECONOMIC ENTOMOLOGY AND FOK THE CLEARNESS AND ACCURACY OF THE PRESENTATION OF HIS WORK TO THE PUBLIC AND ENDEARED TO THE YOUNGER GENERATION OF WORKERS BY HIS KINDLY INTEREST AND ENCOURAGEMENT, THIS BOOK IS DEDICATED AS A TOKEN OF THE authors' ESTEEM PREFACE In the present work we have attempted to bring together in concise and usable form what is known in regard to the habits, hfe history and control of the insect enemies of vegetable-garden crops in the United States and Canada. Much of this infor- mation has been published in technical journals and in the bulletins and circulars of the State Experiment Stations and Federal Government, where it is available only to the special student who has access to the few large libraries that collect and preserve this type of literature. We ha\e endeavored thoroughly to digest this mass of material and present it in a form adapted to the needs of the gardener and vegetable- grower. In regard to methods of control we have tried to eliminate as far as possible useless and imjiracticable recommendations and include only those found to be effective under commercial conditions or such as would seem to be worthy of trial. It has seemed better to state frankly that the problem of control in certain cases has not been solved than to suggest remedies that would lead to disappointment. The chapter on cutworms and the accounts of several others of the lepidoptera were M'ritten in collaboration with Dr. Robert Matheson. We are under great obligation to Dr. W. T. INI. Forbes for criticism and aid with the lepidoptera ; to Dr. E. C. Van Dyke for the determination of beetles ; to jNlr. Charles vii viii PREFACE W. Leiig for the gift of specimens ; to S. W. Frost for the use of photographs ; and to many others for similar favors. The drawings were made by Anna C. Stryke, Ellen Edmonson, Nellie H. Crosby and C. H. Kennedy. Several of the illustra- tions are from photographs previously published in bulletins b\- the late Prof. M. V. Slingerland, by Prof. G. W. Herrick and by H. H. Knight. C. R. Crosby. M. D. Leonard. Cornell University, Ithaca, N. Y. May 28, 1918. CONTENTS CHAPTER I General Considerations PAGE 1 CHAPTER II Insects Injurious to Cabbage and Related Crops Imported cabbage worm Potherb butterfly Southern cabbage liutterfly Cabbage looper . Diamond-back moth Cross-striped cabbage worm Cabbage webworm Garden webworm Purple-backed cabbage Zebra caterpillar . Cabbage aphis Turnip aphis Cabbage root-maggot Seed-corn maggot Western radish 'maggot Harlequin cabbage bug Green soldier-bug Cabbage leaf-miners False chinch-bug . Cabbage eurculio . Cabbage seed-stalk weevil Red turnip beetle . Other insects injurious to cabbage and related crops 4 7 7 9 12 14 IG 18 19 21 22 27 29 3G 37 38 42 43 47 49 50 50 51 CHAPTER III Pea and Bean Insects 54 Pea wee\il .......... 54 Bean wee^al 57 Broad bean weevil ........ 60 ix CONTENTS Four-spotted bean weevil Cowpea weevil Bean leaf-beetle Grape colaspis Bean ladybird Bean thrips . Pea aphis Bean aphis . Garden flea-hopper Pea moth Bean leaf-roller Striped green bean caterpillar Gray hair-strealc . Green clover worm Lima bean vine-borer . Other pea and bean insects CHAPTER IV Beet and Spinach Insects Spinach leaf-miner Beet leafhopper . Larger sugar-beet leaf-beetle Western beet leaf-beetle Sugar-beet webworm . Hawaiian beet Avebworm Spotted beet webworm . Southern beet webworm Sugar-beet root-louse . Spinach aphis Other beet and spinach insects CHAPTER V Insects Injuriotts to Cucumber, Squash and Melon Striped cucumber beetle Western cucumber beetle Twelve-spotted cucumber beetle Western twelve-spotted cucumber beetle Belted cucumber beetle Squash bug ..... CONTENTS XI Horned squash bug Melon Icai'-hug Southern leaf-footed i)lant-l)Uf; Northern leaf-footed plant-bu^ Squash-vine borer Pickle worm Melon worm Squash ladybird . Melon aphis Squash aphis Garden springtail Other cucumber, squash and melon insects CHAPTER VI Potato Insects Colorado potato beetle Three-lined potato beetle Potato aphis Apple leafhoppcn* Potato stalk-weevil Common stalk-borer Burdock borer Potato scab gnat Potato tuber moth Other potato insects CHAPTER VII Tomato Insects Tomato worms Tomato stilt-ljug . Eastern field wireworm Erinose of the tomato Other tomato insects CHAPTER VIII Ecgplant Insects Eggplant tortoise beetle Eggplant lace-bug Other eggplant insects . 177 177 178 179 Xll CONTENTS CHAPTER IX PAGE Insects Injurious to Carrot, Celery, Parsnip and Related Crops . . 181 Carrot riist-fly ......... 181 Carrot beetle . . . . . . . . . 185 Black swallow-tail butterfly ...... 18G Celery leaf-tycr 189 Celery looper . . . . . . . . .191 Tarnished plant-bug . . . . . . . . 192 Negro-bug .......... 196 Parsnip webworni . . . . . . . .197 Parsnip leaf-miner ........ 199 Parsley stalk-weevil ........ 199 Other carrot, celery and parsnip insects .... 200 CHAPTER X Asparagus Insects . (yommon asparagus beetle . Twelve-spotted asparagus beetle . Asparagus miner Other asparagus insects 201 201 205 208 210 CHAPTER XI Corn Insects . Corn ear-worm Corn root-aphis . Southern corn root-worm Western corn root-worm Colorado corn root-worm Larger corn stalk-borer Lesser corn stalk-borer Brown fruit-chafer Stink-bugs . Other corn insects 211 211 218 222 225 227 228 229 231 232 233 CHAPTER XII Sweet Potato Insects ......... 235 Tortoise beetles . . . . . ' . . . . 235 Sweet potato weevil ........ 239 CONTENTS Xlll Sweet potato leaf-roller Sweet potato white-fly Other sweet potato insects CHAPTER XIII Onion Insects Onion maggot Onion thrips Barred-winged onion fly Black onion fly Other onion insects PAGE 241 242 242 CHAPTER XIV Insects Injurious to Minor Vegetahli Rhubarb Okra . Salsify Pepper Water-eress . Lettuce CHAPTER XV Cutworms and Army-worms Spotted ciitworm Well-marked cutworm Greasy cutworm . Red-backed cutworm Dark-sided cutworm Striped cutworm . Dingy cutworm . Shagreened cutworm Granulated cutworm Clay-backed cutworm Black army cutworm Variegated cutworm White cutworm . Glassy cutworm . Yellow-headed cutworm Crops XIV CONTENTS Spotted-legged cutworm Speckled cutworm Clover cutworm . Bristly cutworm . Bronzed cutworm Army cutworm Army-worm . Fall army- worm . Beet army-worm . Yellow-striped army-worm Semi-tropical army-worm Other cutworms . Control of cutworms and army-worms CHAPTER XVI Blister-Beetles Striped blister-beetle . Margined blister-beetle Gray blister-beetle Ash-gray blister-beetle Black blister-beetle Nuttall's blister-beetle Spotted blister-beetle . Two-spotted blister-beetle Miscellaneous ])lister-beetles Means of controlling blister-beetles CHAPTER XVII Flea-Beetles Potato flea-beetle Western potato flea-beetle Tobacco flea-beetle Eggplant flea-beetle Pale-striped flea-beetle Red-headed flea-beetle Smartweed flea-beetle . Striped cabbage flea-beetle Sinuate-striped flea-beetle Western cabbage flea-beetle CONTENTS XV Horse-radish flea-beetle Spinach flea- beetle Yellow-neeked flea-beetle Three-spotted flea-beetle Larger striped flea-beetle Sweet potato flea-beetle Desert corn flea-beetle . Hop flea-boetle Means of controlling: flea-beetles PAGE 328 329 331 331 332 332 334 335 336 CHAPTER XVIII Unclassified Pests Root-knot nematode Sugar-beet nematode . Millipedes . White gi'ubs . Wireworms . Grasshoppers Red-spider . Slugs . . . . Yellow bear caterpillar . Salt-marsh caterpillar . 338 338 342 342 344 347 350 351 354 357 359 CHAPTER XIX Insects and Insecticides Structure of insects Insecticides 361 361 368 MANUAL OF VEGETABLE- GARDEN INSECTS CHAPTER I GENERAL CONSIDERATIONS It was estimated by C. L. Marlatt in 1909 that the annual loss caused to vegetable and truck crops in the United States by insect pests amounts annually to 20 per cent of their value, or $68,000,000. This sum includes the cost of insecticides and other expense incurred in fighting vegetable insects. Insects affect vegetable crops in various ways. They feed on the leaves, devour the roots, tunnel the stems and infest the seeds and fruits. In many cases their injuries to succulent parts of the plant give entrance to decay-producing organisms which greatly augment the damage. Insects also act as carriers of specific diseases, the most remarkable instances of this kind being the transmission of the curly-leaf disease of the beet b}' the beet leaf-hopper and the carrying over winter of the bacterial wilt of cucurbits by the striped cucumber beetle. The enemies of vegetables here treated are, with five excep- tions, members of that class of animals known as insects. These exceptions are : the red-spider and the mite producing erinose of the tomato, which are Arachnids ; snails or slugs, belonging to the molluscs; millipedes belonging to the Myriapoda and the root-knot nematode, one of the true worms. Some vegetable insects are general feeders, attacking a great variety of plants, but the greater number are more or less B 1 2 MANUAL OF VEGETABLE-GARDEN INSECTS restricted to a single family or (jtlier closely related group of plants, both wild and cultivated. Thus many beet insects also feed on weeds belonging to the goosefoot family, cabbage insects on weeds of the mustard family, potato insects on wild solanaceous plants and sweet potato insects on wild morning- glories. This fact, that certain insects form more or less definite associations with certain groups of plants, is of great practical importance and must be kept in mind when considering methods of preventing injury. It also explains why clean farm- ing is one of the most important factors in preventing insect injuries to vegetable crops. In fact, clean farming together with proper cultural practices often makes it unnecessary to re- sort to special remedial measures, or at least renders it possible to obtain more effective results from the use of insecticides. About 250 species of insects have been recorded as serious enemies of vegetable crops in the United States and Canada but a much larger number may occasionally become injurious. Only the more important species are treated in the following chapters, arranged under the crops to which they are most injurious. Flea-beetles, blister-beetles, cutworms and other general feeders are discussed in separate chapters. CHAPTER II INSECTS INJURIOUS TO CABBAGE AND RELATED CROPS L\ this chapter are treated the more important insect enemies of cabbage, cauliflower, brussels sprouts, kohlrabi, kale, col- lards, radish, turnip, mustard and horse-radish. With the exception of horse-radish, these form a natural group of food plants that serves as the common host for a large number of insects, which, although showing a preference for certain crops, can also thrive on the others. ]\lany cruciferous weeds are also food plants of these pests and may serve as centers of in- festation from which the insects spread to cultivated crops. The most important enemies of cabbage and related crops in this country have been imported from the Old World but some of the native insects have found in these succulent vegetables satisfactory food plants. Of European origin are the cabbage root-maggot, the common cabbage worm, the diamond-back moth, the cabbage aphis, the cabbage curculio and the cabbage seed-stalk weevil. The cabbage webworm had its original home in the Old World tropics and the harlequin cabbage bug spread into the United States from Central America during the last half century. Horse-radish has relatively few insect enemies, the most important being the harlequin cabbage bug and the horse- radish flea-beetle. Cabbage and related crops are often seriously injured by cut- worms and flea-beetles. These insects are treated in Chapters XV and XVn. 3 4 MANUAL OF VEGETABLE-GARDEN INSECTS The Imported Cabbage Worm Pontia ra-pcc Linnaeus The common white cabbage butterfly of the United States and Canada is a native of the Old World. It was first intro- duced into America at Quebec about 1860. Later independent introductions occurred at New York in 1868, at Charleston, South Carolina, in 1873 and at Apalachicola, Florida, at about the same date. From these points as centers the insect spread rapidly and by 1885 it occupied practically the whole territory east of the Pacific slope. The favorite food plant of the im- ported cabbage worm is cabbage, but it also attacks cauli- flower, turnip, horse-radish, radish, mustard, gillyflower, nasturtium and sweet alyssum and it also feeds on a number of wild plants belonging to the mustard family. The cater- pillars are sometimes found abundantly on mignonette. The imported cabbage worm hibernates in the pupal state and the white butterflies emerge in early spring, being among the first to appear in our fields and meadows. Their flight is low and unsteady and they alight at frequent intervals. The female deposits her eggs singly on the under surface of the leaves of the food plant. The egg (Fig. 1) is lemon yellow in color, nearly -^ inch Fig. 1- Eggs of tl.e im- j^ j^ ^j^ ^^^ attached to the leaf at ported cabbage butter- ^ fly (X 15). one end. It is broadest two thirds of the distance from the base, and then tapers tn the top, which is flattened. The surface is beau- tifully ridged lengthwise and crosswise. The egg hatches in about a week and the pale greenish yellow caterpillar begins feeding on the under surface of the leaf, which it skeletonizes. A little later the caterpillars are able to eat out holes in the leaves, only the larger veins remaining. When the plants are INJURIOUS TO CABBAGE AND RELATED CROPS . _'. — I iill-gi'i >\\ II iiiii"irtfil (;ubbage worm (, X IJ)- headin*;, tlie caterpillars (iften burrow rather deeply into the head in search of the tenderest leaves. They become full grown in ten to fourteen days. The mature caterpillar (Fig. 2) is about an inch in length, velvety green in color and marked with a greenish yellow stripe down the back and an interrupted one on each side. When ready to pupate, it seeks some sheltered place — ■ under a cabbage leaf or on the underside of fence boards — in which to transform to the chrysalis. When a cabbage patch is near a house, these chrysalids are often found in great numbers under the edge of the clapboards. When about to transform, the caterpillar first spins a carpet of silk over the surface chosen and fastens a deli- cate silken girdle around its body at the first abdominal seg- ment, holding itself tightly in position (Fig. 3). After the transformation is complete the chrysalis is" held in place by this girth. The pupa (Fig. 4) is about f inch in length and of a pale green or yellowish browm color. Except in the case of those chrysalids which winter over, transformation to the butterfly takes place in a week to twelve days. The butterfly has an expanse of about If inches. The wings are nearly white in ground color often more or less suffused with yellowish. The tip of the Fig. 3. — Imported cabbage worm suspended for pupation (X 1^). Fig. 4. — Chrysalis of imported cabbage worm (X 25). MANUAL OF VEGETABLE-GARDEN INSECTS front wing is grayish ; there are two l)hick spots on the front wing of the female and one in the male and in both sexes there is a black spot near the front margin of the hind wing (Fig, 5). Spruig males are smaller and sometimes unspotted. In New England the cabbage butterfly has three broods annually and in the South there are said to be six. Co)itrol. Cabbage worms may be easily killed by spraying with paris green, 1 pound in 50 gallons of water, or arsenate of lead (paste), 4 pounds in 50 gallons of Avater. The first application should be made soon after the plants are set out and repeated whenever the worms become numer- ous. The poison may be applied in the form of a dust diluted with some inert material, such as flour, plaster or hydrated lime, but is not so effective wdien used in this way. Chemical analysis of sprayed plants has shown that there is practically no danger from eating cabbages that have been treated wuth an arsenical. In the home garden jtyrethrum, hellebore or hot water (130° F.) will be found convenient remedies. When only a few plants are grown, hand-picking is often the cheapest and easiest way of destroying the worms. Fiu. 5. — The imported cab- bage worm butterflies, male above, female below ( X f). References Scudder, Butterflies of Eastern U. S., 2, pp. 1175-1190; 1205-1218. 1889. U. S. Bur. Ent. Giro,. 60. 1905. U. S. Farm. Bull. 766. 1916. INJURIOUS TO CABBAGE AND RELATED CROPS The Potherb Butterfly Ponlia oleracen Harris Before the introduction of the imported cabbage butterfly, this species was abundant in the northern I'nited States and Canada east of the Rocky INIoun- tains but soon became rare throughout the greater part of its range. The caterpillar of this species closely resembles that of the imported form but lacks the yellowish dorsal stripe. The butterfly has the upper surface of both i)airs of wings and the under surface of the front wings nearly pure white. The hind wings arc usually marked (jn the underside with gray stripes extending along the veins. Rarely the under surface is pure white (Fig. 6). Fig. 6.- ■ The potherb butter- fly (X f). References Riley, U. S. Ent. Rept. for 1883, pp. 115-117. Scudder, Butterflies of Eastern U. S., 2, pp. 1191-1204. 1889. The Southern (\\bba(;e Butterfly Pontia protodice Boisduval and Le Conte This cabbage-feeding caterpillar is widely distributed through- out the United States but is more common southward, where it often causes serious injury to cruciferous crops. As in the case of the potherb butterfly, this species has decreased in numbers and importance since the introduction of its European relative. The butterfly is known as the checkered white. The ground color of the wings is white in the male and dirty white in MANUAL OF VEGETABLE-GARDEN INSECTS the female and the upper side of the fore wings in both sexes is marked with several black spots (Fig. 7). The caterpillar is about an inch in length, purplish green in color marked with four longi- tudinal greenish yellow stripes and covered with small black dots. The last two species may be con- trolled by the same measures as recommended for use against the imported cabbage worm. Fig. 7. — The southern cab- bage butterfly, male ( X f ) . References Riley, U. S. Ent. Rept. for 1883, pp. 114-115. Scudder, Butterflies of Eastern U. S., 2, pp. 1163-1170. 1889. The Cabbage Looper Autographa brassicce Riley This well-known cabbage pest is a native American insect widely distributed throughout the United States and occurring as far south as Mexico. In some localities, especially in the South, it is the most serious insect with which the grower of late cabbage and cauliflower has to contend. In addition to cruciferous plants such as cabbage, kale, cauliflower and turnip, the cabbage looper may also occasionally cause serious injury to lettuce, celery, beet, pea and parsley. It also feeds on tomato, potato, asparagus, dandelion and dock and some- times attacks carnation and mignonette in greenhouses. On Long Island it is especially injurious to late cauliflower and to lettuce that has been transplanted from coldframes into the forcing houses. The insect as a rule passes the winter in the pupal stage, although it is not improbable that occasionally some of the INJURIOUS TO CABBAGE AND RELATED CROPS 9 Fig. 8. — Erk "f the cabbage loopcr (X 10). later emerging moths may hibernate. In any case, only a relatively small number survive the winter and consequently the first brood of the season is small and causes comparatively little injury. The female moth 'deposits her small whitish eggs singly or in small groups usually on the upper side of the leaves. The egg (Fig. 8) is about -g-^ inch in diameter, pale greenish yellow or nearly white in color, nearly circular in outline and rounded above. The surface is beautifully marked with a series of ridges radiating from the apex. The length of the egg stage has not been deter- mined but it is probably not far from a week or ten days. The young larvpe are pale green in color and feed at first on the outer leaves of the cabbage; as they grow older, they become darker green and are marked with distinct white longitudinal lines. At this time they work in toward the center of the plant, and often bore into the form- ing head. The full-grown caterpillar (Fig. 9) is about 1^ inches in length. It is pale green in color with a white stig- matal stripe and two dorsal stripes extending the whole length of the body. On each side of the dorsal stripe there is a fine white line. The caterpillar is narrower in front and has the body en- larged toward the posterior end which is bluntly trun- cate. Although the cater- pillars are close relati\es of the cutworms, they crawl with a peculiar looping motion like the measuring-worms, due to no prolegs being present on the third and fourth abdominal segments. The caterpillars attain their growth in from two weeks to a month, depending on the temperature. Fig. 9. Full-grown cabbage looper (X If). 10 MANUAL OF VEGETABLE-GARDEN INSECTS When mature the caterpillar spins a light flimsy semi- transparent cocoon (Fig. 10) of white silk about Ij inches in length, usually on the underside of the leaf. It consists of two filmy layers, an inner one close to the pupa and an outer one connected with the other by many fine threads. Soon after completing its cocoon, the larva transforms to a dark brown or blackish pupa (Fig. 11) about f inch in length. The moth (Fig. 12) emerges Fig. 10. — Cocoon of the "^ ten days to two wecks ; it has a'n cabbage looper from expanse of l| to 1^ inches. The front which the moth has . 111 • i 1 • , 1 emerged (xf). wmgs are dark brown variegated with lighter brown and bear near the center two silver spots, one oval and the other shaped like a con- stricted U. Sometimes these spots are united and resemble an imperfect figure 8. The hind wings are mouse-colored with bronze reflections in certain lights. There are said to be three broods of the insect annually on Long Island, New York, and four at Washington, D. C. As only a relatively small number of pupae survive the winter, the first brood caterpillars are gen- erally not abundant enough to cause much injury and are usually overlooked entirely. The succeeding broods increase rapidly in numbers and impor- tance, the last being the most destructive. Towards the end of the season, the broods over- lap so that all stages of the insect are present on the cabbage plants at the same time. The cabbage looper is held in check by several parasites and Fig. 11. — PupjE of the cabbage looper (X 2f). INJURIOUS TO CABBAGE AND RELATED CROPS 11 by a disease. Diseased caterpillars at first turn yellowish and later take on an ashy hue (Fig. 13). They become inactive, stop feeding and soon die. After death the skin breaks open and the body contents which have become liquid oozes out and becomes smeared on the leaves. Sometimes a large proportion of the caterpillars are de- stroyed by this disease late in the season. Control. The cabbage looper is a difficult insect to Fig. 12. — Moth of the cabbage looper (X I3). poison because the caterpillars refuse to eat leaves coated with an insecticide and move quickly to some part of the plant that has been missed in spraying. Furthermore, it is not easy to spray a cabbage plant so as to cover all parts of the leaves, especially the underside of the outer leaves and those in the forming head. Experiments on Long Island have shown that good results may be obtained by thorough spraying with paris green, 1 pound in 80 gallons of water to which the resin- lime mixture has been added. Some growers dust the plants lightly with pure paris green and have reported satisfactory results from this treatment. Fig. 13. A diseased cabbage looper (Xli). 12 MANUAL OF VEGETABLE-GARDEN INSECTS References Riley, U. S. Ent. Rept. for 1883, pp. 119-122. N. Y. (Geneva) Agi'. Exp. Sta. Bull. 83, pp. 667-671. 1894. N. Y. (Geneva) Agr. Exp. Sta. Bull. 144. 1898. The Diamond-Back Moth Pluiella maculipennis Curtis In this country the diamond-back moth is rarely more than a minor enemy of cabbage and related crops, but in some parts of its extensive range its injuries are of considerable importance. Apparently introduced from Europe some time before 1854, the insect is now widely distributed throughout the United States and Canada ; it also occurs in South America, Australia, New Zealand, South iVfrica, India, Greenland and Spitzbergen. It seems able to maintain itself wherever its food plants are grown, whether in the tropics or in the arctic region. In Eng- land the insect is also known as the turnip fly and in some parts of the United States it is called the shot-hole worm. Besides cabbage, cauliflower, brussels sprouts, rape, horse-radish, radish, kale, mustard, turnip and water cress, the insect attacks stocks, wall-flowers, sweet alyssum and candytuft. It some- times becomes very troublesome on these plants in green- houses. The diamond-back moth hibernates in the adult condition hidden away under the cabbage leaves left in the field. The moths appear in the spring as soon as food plants are available on which to deposit their eggs. The moth (Fig. 14) has an expanse of about f inch. In the male the front wings are ash- colored dotted with minute dark spots and have a yellow stripe outlined by a wavy dark line extending along the hind border. When the wings are closed, the united yellow stripes form a row of three diamond-shaped markings. In the female the front wings are a nearly uniform gray. The hind wings in both sexes INJURIOUS TO CABBAGE AND RELATED CROPS 13 Fici. 14. ^- The diamond-back moth, male (X3f). are dull gray. When at rest the moth has the wings slightly turned up at the tip and the antennae are held extended forward. The female moth deposits her minute whitish or yellowish eggs, Yi inch in diameter, singly or in groups of two or three, usually on the leaves. Each moth is capable of lay- ing on an average nearly 300 eggs during a period of one to two weeks. They hatch in three to six days and the young caterpillars first eat holes in the leaf from beneath but do not cut through to the upper surface. Later the upper epidermis dies, turns brown and drops out leaving the leaf riddled with holes. Sometimes in cool weather the young larvae li\^e as miners in the leaf for twf) to four days. The caterpillars are very active when dis- turbed, wriggle from the leaf and suspend themselves by a thread till the danger has passed. The larva reaches maturity in nine to twenty-eight days. It is then only about I inch in length, pale green in color and sparsely clothed with small, erect black hairs ; Fig. 15. ^Cocoon of the d.am,.nd-l,a.k moth the head is brOWnish showing the larva within (X 4). yclloW mottlcd with black. The larvae be- come mature in about a month and spin their beautiful open- work cocoons (Fig. 15), so loosely woven that the pupa can be plainly seen within, on the underside of the leaves. In the summer from four to thirteen days are spent in the pupal 14 MANUAL OF VEGETABLE-GARDEN INSECTS stage. In the northern states there are two or three broods annually, which overlap to a considerable extent, but in the tropics breeding is almost continuous. In Colorado there are seven generations annually. On Long Island, larvte and moths are often abundant on cauliflower until early December. The insect is usually more destructive in dry seasons than when rains are abundant. On cabbage the greatest injury is usually inflicted early in the season while the plants are small, but in the case of cauliflower the late broods are the most troublesome. A closely related species, Plutella armoracia Busck, has been reported as injurious to horse-radish in Colorado. Its habits are similar to those of the diamond-back moth. Control. Experiments in Colorado have shown that the diamond- back moth can be controlled by spraying with 2 pounds of paris green and 6 pounds of soap in 100 gallons of water, or arsenate of lead (paste), 8 pounds in 100 gallons. Reference.s Fitch, 1st Rept. State Ent. N. Y., pp. 170-17.5. 1856. Carpenter, Rept. for 1901, pp. 144-147. 1902. Quanjer, Tijds. Ent. 49, pp. 11-17. 1906. Marsh, Jour. Agr. Research, 10, pp. 1-10. 1917. The Cross-Striped Cabbage Worm Evergestis rimosalis Guenee While widely distributed throughout the United States ex- cept in the extreme north, the cross-striped cabbage worm is most abundant and destructive in the southern states. Locally in some years it often causes more injury than the imported cabbage worm and its native relatives. The caterpillars destroy the leaves in much the same way as the common cab- INJURIOUS TO CABBAGE AND RELATED CROPS 15 })age worm and have an especial fondness for the tender central leaves and forming head, often burrowing into the latter. In addition to cabbage and related crops, this insect has been reported as feeding on nasturtium in California. The insect hibernates in the pupal stage in a snug cocoon just below the surface of the ground. The moths emerge in early spring — in April in the District of Columbia. The moth (Fig. 16) has an expanse of about an inch. The front wings are pale ocher-yellow in color, marked with an indistinct zigzag brownish line and suffused with various shades of brown, darker towards the middle of the outer margin. The hind wings are nearly transparent towards the base, fuscous at the front angle and marked across the disk with a row of five or six small indistinct dusky spots. The female moth deposits her light yellow, rounded oval eggs about ^ inch in diameter, in cir- cular masses on the underside of the leaves. Each egg-mass con- tains twenty to thirty eggs which are flattened and overlap. They are semi-transparent and the green of the leaf shows through the mass. The eggs hatch in about six days and the young caterpillars begin feeding on the leaves, eating out long oval holes. The newly hatched larva is of a nearly uniform gray color. When full-grown it is about yu i'^ch in length, bluish gray above with distinct transverse black stripes, three or more to each segment. On the side a wide stigmatal line of bright yellow extends from the second to the last segment. Beneath, the caterpillar is green mottled with yellowish. In the summer the caterpillars reach maturity in about a month, but in the cooler months a somewhat longer period is required. When full- grown the caterpillar descends to the ground and just below Fig. 16. — The moth of the cross-striped cabbage worm (X If). IG MANUAL OF VEGETABLE-GARDEN INSECTS the surface constructs a tight cocoon into the outer surface of which bits of dirt and sand are incorporated. The cocoon is I inch in length by | inch in width. The pupa is f to ^ inch in length and has the head and wing-cases dark brown and the abdomen light yellowish brown. The summer broods of the insect spend about ten days in the cocoon but the time in the pupal stage has not been determined. It is probably about six days. There are supposed to be three generations annually. The cross-striped cabbage worm may be controlled by the measures suggested for the imported cabbage worm. Reference U. S. Div. Ent. Bull. 33, pp. 54-59. 1902. The Cabbage Webworm Hellula undalis Fabricius Originally a native of the tropical and subtropical regions of the Old World, the cabbage webworm was introduced into the southern United States shortly before 1895 and now ranges as far north as North Carolina and west to Oklahoma, Texas and southern California. It also occurs in Australia and Guam. This webworm attacks cabbage, cauliflower, collard, turnip, radish, mustard, horse-radish and beet and will feed on shep- herd's purse and purslane. It is sometimes destructive to plants in seed-beds. In the southern United States, the insect hibernates as a pupa in a compact cocoon of white silk attached to the injured plant near the base or situated just below the surface of the ground. The early seasonal history is very imperfectly known and the number of generations annually has not been definitely deter- mined. The moth has an expanse of about f inch ; the front wings are brownish yellow mottled with darker brown ; the INJURIOUS TO CABBAGE AND RELATED CROPS 17 hind wings are pale fuscous. The female deposits her eggs singly or in small masses on the lea\'es of the plant. The egg is about sV inch in length, flattened and often provided with a distinct nipple-like projection at one end. When first laid it is light yellow or grayish but just before hatching takes on a pinkish browm color. Each female is capable of laying from 300 to 350 eggs. In warm weather the eggs hatch in three or four days. The young caterpillars begin feeding on the underside of the leaves, eating off the epidermis in small irregular patches. The caterpillars often burrow into the leaf itself, into the leaf-stems and into the developing head. After the first molt, the cater- pillar usually covers its feeding grounds with a web of silk on which the excrement and other dirt collect. The caterpillars often attack the bud or heart of the plant, stop its growth and in many cases kill it outright. They sometimes eat out holes in the upper part of turnip roots. When full-grown, the caterpillar is about f inch in length, dull grayish yellow in color, and marked dorsally with five conspicuous brownish purple longitudinal stripes. On the sides and below there are similar but less distinct stripes. The caterpillars become full-grown in about eighteen days and after constructing their cocoons transform in a day or two to pupse. The pupa is about -^ inch in length and light yellowish brown in color. In the summer the insect spends about six days in the pupal state. There are probably three or four generations a year but the exact number has not been determined under field conditions. Control. In regions in which the cabbage webworm is likely to appear in injurious numbers, the plants should be protected by fre- quent applications of arsenicals beginning soon after trans- planting. In this way the young caterpillars will be killed c 18 MANUAL OF VEGETABLE-GARDEN INSECTS before they are able to spin their proteetive webs. After the webs are spun, it is praetieally impDssibk' to reach them with a poison spray. Paris green, 1 pound in 50 gaUons of water, or arsenate of lead (paste) , 4 pounds in 50 gallons of water, will be found effective. In cases of severe infestation it would pay to collect and destroy the stumps and other refuse in the field after the crop is harvested and thus greatly reduce the number of hibernating pupse. References U. S. Div. Ent. Bull. 19. pp. 51-57. 1899. Ga. State Bd. Ent. Bull. 1, pp. 17-25. 1899. U. S. Div. Ent. Bull. 2.3, pp. 53-Gl. 1900. U. S. Bur. Ent. Bull. 109, pp. 23-45. 1912. The Garden Webworm Loxostege similalis Guenee Many kinds of vegetables are injured by a small dark yellow caterpillar feeding under the protection of a silken web. The insect is widely distributed throughout North and South America and the West Indies but is most injurious in the south- ern states and in the Mississippi Valley. The favorite food plants of the caterpillar are pigweed and careless weed {Amaranius hybridus) ; it also attacks a wide range of cultivated plants, including cabbage, cucumber, melon, squash, pumpkin, sweet potato, potato, tomato, eggplant, beet, bean, pea, lettuce, onion, corn, tobacco, flax, sugar-cane, clover, alfalfa and many grasses. How the insect passes the winter is not known, though judging from the habits of a closely allied species, Loxostege sticticalis, it probably hibernates as larvte in silken tubes in the ground. In Texas the first brood of moths is on the wing in early May ; in Illinois in late May and June. The moth has an INJURIOUS TO CABBAGE AND RELATED CROPS 19 expanse of about f inch. The front wings are reddish buff marked with several transverse, interrupted Ughter Hues. The hind wings are hghter in coh)r with darker marginal and discal bands. The eggs are laid on the surface of leaves in bunches of eight to twenty. Hatching takes place in three or four days and the young larvpe at first feed on the under surface of the leaves, skeletonizing them, and spin a silken web inclosing their food. The larger caterpillars devour the entire leaves. They become mature in three or four weeks. The full-grown cater- pillar is nearly an inch in length, dull green above and greenish yellow below, marked on the dorsal surface with numerous shining black piliferous spots. The body is marked with a double pale median line and a whitish lateral line. Pupation takes place in a delicate silken cocoon spun among the debris at the base of its food plants. The pupa is brown in color. In the South there are probably as many as five generations while in Illinois Forbes records four broods annually. References Riley, Rept. U. S. Ent. for 1885, pp. 2().")-270. U. S. Bur. Ent. Bull. 57, pp. 11-14. 190G. The Purple-Backed Cabbage Worm Evergestis straminalis Hiibner Although this insect is common throughout the northeastern United States and Canada, it has been reported as injurious only in the maritime provinces. The insect also occurs in Europe. Its food plants include cabbage, turnip and horse- radish. When infesting the last, it is known as the horse- radish webworm. The caterpillars feed on the leaves, often webbing them together, and sometimes attack the crown boring into the stems and roots. The full-grown caterpillar is about 20 MANUAL OF VEGETABLE-GARDEN INSECTS f inch in length, bristly, with the body tapering at both ends. The back is purplish brown to dark greenish black. There is a vellow stripe running through the spiracles and the underside of the body is dull greenish. The head is black, the cervical shield is black on the sides and the body is marked with numer- ous black tubercles. The larvae become full-grown in a little over a month and construct thin silken cocoons covered with dirt at or just below the surface of the ground. The larvae of the summer brood soon transform to pupae but those of the fall brood remain in the larval condition until the following spring. The pupa is about ^ inch in length and brow^nish in color. The moth has an ex- panse of nearly an inch. The front wings are bright straw- yellow crossed with two fine brown lines and the veins are more or less lined with brown. On the outer margin of the wing there is a broad, brown shade inclosing a triangular straw- colored spot. The hind wings are straw-colored, translucent white at the base with brown marginal and submarginal lines, the latter usually incomplete and sometimes lacking. The moth deposits her eggs in small flat masses of three to more than a dozen, the eggs overlapping in the cluster. The egg is ovate and very flat when first laid but gradually swells with the development of the embryo. It is brownish yellow in color. The egg hatches in eight days. There are two and possibly three generations annually, the fall brood of caterpillars being the most injurious. Fortunately the purple-backed cabbage worm rarely becomes sufficiently abundant to require remedial treatment. Spray- ing with arsenate of lead (paste), 2 pounds in 50 gallons of water, should give satisfactory results. References Buckler, Ent. Mo. Mag. 19, pp. 126-130. 1882. Fletcher, Rept. Ent. Canada for 1904, pp. 231-232. INJURIOUS TO CABBAGE AND RELATED CROPS 21 The Zebra Caterpillar Mamestra picta Harris In the northern United States and Canada east of the 100th meridian, a black, yellow-striped caterpillar is often seen in June and July and again in the fall feeding on the leaves of many garden plants. Its _ „____„ _— ^ mm^- Fi(i. 17. — Full-grown zehru caterpillar (X i). striking colors often attract attention but the insect rarely becomes injurious except occasionally on cab- bage and celery. The full- grown caterpillar is about two inches in length, black, with bright yellow stripes on each side of the body (Fig. 17). The back between the yellow stripes is dotted with fine yellow spots and the space between the yellow bands on the side is crossed by fine slightly reticulated yellow lines. The head, legs and underside of the body are dark red. The caterpillars become mature in about a month and then enter the ground where in slight silken co- coons they transform to shining brown pupse about f inch in length. In the summer the pupal period is two or three weeks. The moth has an expanse of 1| to If inches. The front wings are purplish brown with a shade of light brown across the hind part of the wing. The round and reniform spots are gray. The hind wings are white edged with brown on the front and outer margins (Fig. 18). The moth deposits her globular, Fig. 18. Moth of the zebra caterpillar (X U). 22 MANUAL OF VEGETABLE-GARDEN INSECTS sUfihtly flattened eggs in compact clusters of 125 to 150 or more on the underside of the leaves. The eggs hatch in a week or two and the young caterpillars feed for a time in colonies, skeletonizing the leaves, but later scatter and feed singly. They are at first nearly black but soon become pale or greenish and then develop the characteristic markings of the mature larva. There are two generations a year, the first brood of caterpillars being found in June and July and the second in the fall. The insect may hibernate either as partly grown caterpillars or in the pupal stage. The zebra caterpillar rarely becomes sufficiently abundant to require remedial measures on crops grown under commercial conditions. The young caterpillars may be killed by spraying with paris green or arsenate of lead. In the home garden hand-picking is the most satisfactory remedy. A closely related species, Mamestra legifima Grote, sometimes known as the striped garden caterpillar, has been reported as a general feeder on vegetable crops in the District of Columbia and in Georgia. The larva of this species differs from the zebra caterpillar in having the stigmatal yellow stripe broadly bordered with black above. In habits and life history, the two species are similar. The Cabbage Aphis Aphis brassiccE Linnaeus The cabbage aphis is supposed to be of European origin, but now occurs over practically the whole world wherever its food plants are cultivated. It attacks cabbage, cauliflower, brussels sprouts, kohlrabi, coUard, kale, brocolli, rape, turnip and radish. It also breeds to a considerable extent on a number of wild plants belonging to the mustard family. In the United States, especially in the northern and eastern states, it often takes first rank as an enemy of cabbage, cauliflower and related INJl'RIOUS TO CABBAGE AND RELATED CROPS 23 Fig. 19. — Egg of tho cabbage aphis (X 19). plants. In some seasons the losses are severe, the crops over large areas being so badly infested that the growers plow them under early in the season. In that part of its range in which the winters are severe, the cabbage aphis hibernates exclusively in the egg stage; farther south many of the lice doubtless survive the winter. The elongate, oval, smooth, black, shiny eggs (Fig. 19), about ■g^ inch in length, are found abundantly on the petioles and under surface of the leaves of cabbage plants left in the field over winter. Early in the spring the eggs hatch and the young lice find abundant food in the tender sprouts thrown out by the old cabbage stumps (Fig. 20). These lice of the first generation hatching from the eggs are all wingless females and are known as stem-mothers. As they increase in size, the lice molt four times, reaching maturity in about two weeks. A few days after the last molt they begin to give birth to living young. These stem-mothers may live for six weeks or more and give birth to forty or fifty young. The next generation of lice consists of wingless agamic females which resemble the stem-mothers very closely in form and color, being about j -^ inch in length, grayish green ^ .„, c-^ .1 r 7i i" color and covered with a biLi. 20. — Stem-mothers of the i • • i cabbage aphis feeding on a whltlsh Waxy bloOIll (Fig. 21). sprout thrown out by an old Dm-Jug the remainder of the cal)hage stump (greatly eu- largcd). season reproduction continues 24 MANUAL OF VEGETABLE-GARDEN INSECTS vivip- Fifi. 21.— Win arous female of the cabbage aphis (X 8j). parthenogenetically, no eggs are produced and the young are born alive. From April first to October first, sixteen genera- tions have been known to develop. From time to time when the food supply be- comes limited, either from overcrowding or from some injury to the plant, winged forms (Fig. 22) are developed which fly to other plants and start new colonies. Cabbage plants often become infested in the seed-beds or very soon after transplanting. The lice soon become closely packed together in dense masses, often hiding the leaf from view. Their presence causes the leaves to curl, some- times forming deep pocket-like depressions, the inner surface of which is completely covered with lice. The aphids also cluster in the forming head. Badly infested plants cease to grow, the larger leaves die, the heads do not develop and in some cases the plant is killed outright. Figure 23 shows a badly infested radish seed-stalk. Late in the fall, true males and females are produced. The female is wingless and the male is winged. After pairing the female soon begins to deposit her eggs on the petioles and under surface of the cabbage leaves. When first laid, the eggs are pale greenish yellow in color but usually turn black in a few days. Fig. 22. — Winged viviparous female of the cabbage aphis (X 82). Control. Although cabbage lice are easily killed when hit by ordinary contact insecticides, it is difficult to control them economically under commercial conditions. The lice are pro- INJURIOUS TO CABBAGE AND RELATED CROPS 25 tected in the curled leaves where it is difficult to hit them with a spray ; their bodies are covered with a white waxy bloom so that the spray does not readily wet them ; and they occur in dense masses or colonies, and considerable force is required in order to reach those beneath the others. Under commercial condi- tions, it is not possible to destroy all the lice by spraying. The best that can be expected is so to reduce their numbers that the plant will be able to continue its growth and develop the head. Efficient work can be done by spray- ing with the so-called whale-oil or fish-oil soap, 10 pounds in 100 gallons of water, or with " Black Leaf 40" tobacco extract, f pint in 100 gallons of water with 4 or 5 pounds of soap added. The first application should be made as soon as the lice begin to cluster on the young plants. At least 100 gallons should be applied to each acre when the plants are young. The most effective and economical method of application is to use an ordinary potato sprayer (Fig. 24) equipped with a Y to which are attached two leads of hose 10 or 12 feet in length. At the end of each hose is an Fig. 2.3. — A radish seed-stalk infested by the cabbage aphis (enlarged). 26 MANUAL OF VEGETABLE-GARDEN INSECTS extension rod about 20 inches long, furnished with a Bordeaux or Vermorel nozzle, preferably the former. The pump should be able to maintain a pressure of at least 125 pounds. With this arrangement three men are needed, one to drive the horse and two to carry the nozzles. Attempts to use a potato spra>'er with fixed nozzles have been unsuccessful. A stiff Fiu. 24. Spraying for the cabbage aphis witli a traction potato-sprayer and two leads of hose. spray should be used, directed downward into the center of the plant. With sufficient force it will be driven into many of the curled leaves and will reach the lice. If the plants become infested with lice in the seed-beds, they should be dipped in a solution of whale-oil soap, 1 pound in 8 gallons of water, before transplanting. The roots should not be wet with the solution and the plants should not be left in the sun after dipping for fear of l)urning. Reference Cornell Agr. Exp. Sta. Bull. 300. 1911. INJURIOUS TO CABBAGE AND RELATED CROPS 27 The TruNiP Aphis Aphis pseudohrdssica; Davis Although the tiinii}) aphis has undoubtedly been causing serious injury to cruciferous crops for many years, particularly in the South, it has been confused with other forms and its injuries attributed to other species. This aphid was not recog- nized as a distinct species until 1914 when it was described from specimens collected in New York and Indiana. It has received careful study in Texas where it is a serious pest of turnip, radish, cabbage and mustard, but is also found on kale, collard, rutabaga, rape and lettuce. It has been reported as feeding on bean but this attack w^as probably exceptional. The turnip aphis is most destructive in the fall, winter and early spring. Reproduction is rapid and the plants soon become covered with the lice, especially on the underside of the leaves anfl on the tender leaves at the center of the plant. Badly infested plants are stunted and many of them killed outright. The insect is distributed from Massachusetts to California southward to Louisiana and Texas and has been found in South Africa. So far males and egg-laying females (the so-called true sexes) of the turnip aphis have not been observed. In Texas the aphids pass the winter mostly on turnips. In that climate reproduction is considera})ly slower in the winter months but does not actually cease except for a few days at a time. Both wingless and winged forms occur at all seasons of the year but the relative abundance varies with the crowding of the plants and with their vitality. The wingless form when mature is a little over ^ig" hich in length, pale greenish, with the antennae pale, blackish towards the tip ; the legs are pale with the tips blackish. The body is slightly pulverulent, but much less so than in the cabbage aphis. The winged form is a little less 28 MANUAL OF VEGETABLE-GARDEN INSECTS than Yt iii<^h "^ length, the head and thorax are black and the abdomen apple-green. The legs and antenna? are much darker than in the wingless form. Both forms give birth to living young. In the course of its development the aphis passes through four nymphal stages and becomes mature after the fourth molt. This requires from five to twenty-five days for the wingless forms and for the winged forms twelve to sixteen days, depending on the temperature. Rearing from the first born of each generation, thirty-five generations have been secured in one year in Texas. The number of young produced by each female varies considerably, from twenty-five to over one hundred, born over a period of eleven to twenty-seven days. During the summer in Texas, the turnip aphis is not found on cultivated plants, but its wild host plants have not yet been determined. In Indiana it is found abundantly on wild mustard and in Colorado on shepherd's purse. Control. The turnip aphis can be controlled by thorough spraying with "Black Leaf 40" tobacco extract, f pint in 100 gallons of water to which 4 or 5 pounds of soap have been added. This material will kill all the lice wet by the spray, the great difficulty being in hitting them. Spraying should begin early, when the first colonies of lice are found. Good pressure should be used and the spray applied with upturned angle nozzles, so directed as to wet the underside of the leaves. Effective work can also be done by spraying with whale-oil soap or laundry soap, 1 pound in 7 gallons of w^ater. References Tex. Agr. Exp. Sta. Bull. 180. 1915. Ind. Agr. Exp. Sta. Bull. 185. 1916. INJURIOUS TO CABBAGE AND RELATED CROPS 29 The Cabbage Root-^NIaggot Phorhia brassiccc Bouehe Throughout the greater part of the United States and Canada and in Europe, cabbage, cauhflower, turnip, radish and related crops are subject to serious injury by a small whitish maggot that burrows in the roots. It is also destructive in Alaska. In the northern states and Canada it is especially injurious to early cabbage and is very troublesome in the seed-beds of late cab- bage. Radishes also rarely escape attack. In some regions the growing of these crops has been abandoned temporarily because of the ravages of this pest. The parent flies, as a rule, emerge in early spring and have been recorded as feeding on the pollen of flowers. In the latitude of New York they emerge from the middle of JNIay till the middle of June and may be seen around the plants searching for a favorable place in which to deposit their eggs. In British Columbia eggs have been found as early as April 10. The fly is about 3- inch in length and resembles the house-fly in general appearance. The male (Fig. 25) is dark ash-gray in color with three blackish stripes on the thorax ; there is also a wide black stripe on the abdomen, which is continued laterally along the edge of the segments. The female is lighter in color and the Fig. Male fly of the cabbage root- maggot (X 5§). 30 MANUAL OF VEGETABLE-GARDEN INSECTS stripes are less distinct than in the male. This species is dis- tinguished from its near relatives by the presence, in the male fly, of a small tuft of bristles on the underside of the base of the hind femur (Fig. 26 ^4). As yet no one has discovered any characters by which the females can be distin- guished from those of the seed-corn maggot. The female deposits her small white eggs at the base of the plant, carefully tucking them down between the soil and the stem. Some- times the eggs are attached to the stem above ground. The egg is slightly over gV inch in length, elongate, bluntly rounded behind and pointed and flattened anteriorly, whitish in color, longitudinally striate and deeply grooved on one side. The eggs hatch in four to ten days depending on the weather. On hatching, the young maggot works its way along the main root, on which it feeds by rasp- ing out a channel in the surface. The maggots first attack the tender rootlets and then burrow into the main root where they may be found in slimy burrows just under the bark. They are sometimes seen in the stem above ground and even in the midrib of the leaves. Usually the first indication that Fig. 2G. — The femur and tibia of the hind leg of the male fly of: A, cabbage root- maggot ; B, onion maggot; C, seed-corn maggot. INJURIOUS TO CABBAGE AND RELATED CROPS 31 Fig. 27. — Cabbage root-maggots at the base of an injured plant. a cabbage plant is seriously infested is a tendency to wilt l)a(lly in the heat of the day ; the leaves take on a blnish cast and then in a few days the plant droops and dies or it may survive in a sickly condi- tion for some time. When the maggots are present in great numbers, the root is riddled with their bur- rows, decay sets in and the death of the plant quickly ensues. In such cases great numbers of the maggots may be found in the soil surrounding the root, moistened by the juices of the injured plant (Fig. 27). The maggots become full-grown in about three weeks. They are then nearly | inch in length and shin- ing white in color. The body tapers toward the head, being largest be- hind, where it is obliquely truncate. The mouth-parts consist of a pair of strong black hooks curved downward, by which the insect is able to rasp off portions of the posterior end of the fleshy tubercles, of Fig. 28. — The cabbage root-maggot, side view ( X 8) ; a, dorsal view of caudal segment, showing size, number and arrangement of fleshy tubercles, much enlarged ; b, outline of a cephalic spiracle, greatly enlarged. plant tissue. The truncate surface at the body is surrounded by a row of twelve mmm^' 32 MANUAL OF VEGETABLE-GARDEN INSECTS which the middle hiwer pair are two-toothed. At the side of the body just back of the head is located a pair of spiracles which appear as brownish fan-like projections each having twelve divisions. These characters are used in separating the cabbage maggot from its near relatives (Fig. 28). When full-grown, the maggots work their way into the soil an inch or so, and there the skin contracts, hardens and turns brownish, thus forming the puparium (Fig. 29). Sometimes the maggots make this change in cavities in the roots. Within the puparium there takes place a remarkable series of changes whereby the tissues of the larva are broken down and rebuilt into the organs of the fly. The fly escapes from the puparium . through a circular seam at one end ; the length of the period passed in the puparium varies greatly; most of the flies emerge in twelve to eighteen days ; Fig. 29. — Puparium of a few may appear sooner, and a con- got {X7)^^ ^°ot-mag. siderable number emerge irregularly throughout the remainder of the season. A few puparia of this first brood may hold over till the following spring. A second brood of flies appears the last of June anfl throughout July. A third brood emerges from August till October. In some seasons a partial fourth brood may occur. As a rule it is the first brood of maggots that is most destructive to cabbage, cauliflower, radish and turnip, although occasionally the second brood causes seri- ous damage. The wuld plants in which breeding takes place are hedge mustard, white mustard and winter cress or yellow rocket, and probably other members of the mustard family, although shepherd's purse seems to be immune. In Canada the flies have been reared from maggots infesting the roots of bean and beet. In the North, as a rule, the insect hibernates in the puparium stage, but occasionally a few of the flies emerging late in the season may pass the winter under the protection of the INJURIOUS TO CABBAGE AND RELATED CROPS 33 cabbage plants in the field. It is quite probable that farther south a greater number of the flies hibernate. Control. The means employed for the control of the cabbage maggot vary greatly with the character of the crop infested. For early cabbage and canliftower. — When infesting these crops, the injury may be in great measure prevented by the use of carbolic acid emulsion. For this purpose the stock emulsion is diluted with thirty parts of water. About half a teacupful of the emulsion sht)uld be poured around each plant a day or two after transplanting. The application should be repeated every week for a month. Apparently the carbolic acid emulsion does not to any great extent deter the flies from laying their eggs, but is effective in killing the eggs and recently hatched maggots with which it comes in contact. This method has been used to a considerable extent by commercial growers, but has not on the whole been found so satisfactory as the use of tarred paper cards. The value of the use of tarred paper cards to prevent maggot attack on early cabbage and cauliflower was demonstrated many years ago, but has not come into general use by commercial growers. This method of protection is more effective and at the same time less expensive than carbolic acid emulsion, and there is also no danger of injuring the plants. The cards are made of one-ply tarred felt roofing paper, and are cut in the form of a hexagon 4| inches in diameter. From one angle a slit extends to the center of the card and radiating from the center there are four to eight short slits whereby the card can be made to fit snugly around the stem of the plant (Fig. 30). The cards should be applied as soon as the plants are set out. To be most effective, the plants should be set on a ridge rather than in a depression because in the latter case the cards are likely to be- come covered with dirt. Thev cannot be used on short-stemmed 34 MANUAL OF VEGETABLE-GARDEN INSECTS >< Fig. 30. — Outline of tarred paper card ( X 3) . plants set sd deeply in the ground that the leaves are partly buried. After having been placed in position, the cards should be pressed down so as to rest smoothly on the soil and thus prevent the flies from working under them. The tarred pads can be obtained from seedsmen and dealers in garden sup- plies or the grower can make them himself by using the tool shown in Fig. 31. The method is described by Goff as follows : "The blade of the tool, which should be made by an expert blacksmith, is formed from a blade of steel, bent in the form of a half hexagon, and then taking an acute angle, reaches nearly to the center. The part making the star-shaped cut is formed from a separate piece of steel, so at- tached to the handle as to make a close joint with the blade. The latter is beveled from the outside all around, so that by remov- ing the part making the star-shaped cut, the edge may be ground on a grindstone. It is important that the angles in the blade be made perfect, and that its outline represents an exact half hexagon. "To use the tool, place the tarred ■^ „., ,,. , paper on the end of a section of a log Fig. 32. — Diagram show- ' ^ . . ° ing how the tool is used, or piece of timber and nrst cut the The dotted line indicates j^^^^. ^^j j^^^^ notchcs. as indicated in the position of the edge ° 1 j> u of the tool. • Fig. 32, using only one angle ot the Fig. 31. — Tool for cutting the cards ( X j). INJURIOUS TO CABBAGE AND RELATED CROPS 35 tool. Then commence at the left end, and place the blade as indicated by the dotted lines, and strike at the end of the handle with a light mallet, and a complete card is made. Con- tinue in this manner across the paper. The first cut of every alternate course will make an imperfect card, and the last cut in any course may be imperfect, but the other cuts will make perfect cards if the tool is correctly made, and properly used. "The cards should be placed about the plants at the time of transplanting. To place the card bend it slightly to open the slit, then slip it on to the center, the stem entering the slit, after which spread the card out flat, and press the points formed by the star-shaped cut snugly around the stem." For late cabbage seed-beds. — The depredations of the maggot in late cabbage seed-beds are often severe and necessitate the growers making much larger plantings of seed than would otherwise be required. Screening the beds with cheesecloth has been found an efficient and practicable method of protection and is now regularly practiced by cabbage growers in certain localities in New York. When this method is used, the seed should be drilled rather thickly in rows 6 to 8 inches apart. The corners of the bed should be staked out so that the cover can be applied before the plants come up. Boards, 6 to 10 inches wide, are placed on edge around the bed making a tight enclosure and a cheesecloth cover is stretched over the top. The cloth is supported on galvanized wires stretched across the bed every 4 or 5 feet. The wires are sometimes supported at the middle by short stakes. The cloth is fastened to the boards by strips of lath. Care should be taken to have the boards fit tightly at the corners and at the ends, and the earth should be banked up around the bottom so that the flies cannot work their way under. E^'en the cheaper, loosely wo\en grades of cheese- cloth will exclude the flies, but as cloth ha\ing less than twenty threads to the inch is likely to stretch and pull apart so as to let in the flea-beetles, it is better to use cloth ha^'ing twentv 36 MANUAL OF VEGETABLE-GARDEN INSECTS to thirty threads to the inch. Cloth that is too tightly woven will exclude too much sunlight and make the plants spindling. The screen should be removed a week or ten days before trans- planting in order to harden the plants. Plants grown under cheesecloth cover are not only protected from the attacks of root-maggots and flea-beetles but, owing to the retention of warmth and moisture, make a much better growth than in the open. Screened beds do not have to be as large as open beds because under these conditions practically all the plants make the proper growth. For radishes. — Carbolic acid emulsion has been used with some success on this crop, but better results can be obtained by growing the plants in beds screened with cheesecloth as de- scribed above. References Cornell Agr. Exp. Sta. Bull. 78. 1894. N. J. Agr. Exp. Sta. Bull. 200. 1907. N. Y. (Geneva) Agr. Exp. Sta. Bull. 301. 1908. N. Y. (Geneva) Agr. Exp. Sta. Bull. 334. 1911. N. Y. (Geneva) Agr. Exp. Sta. Bull. 382. 1914. N. Y. (Geneva) Agr. Exp. Sta. Bull. 419. 191(). Dept. Agr. Canada Ent. Bull. 12, pp. 9-29. 1916. N. Y. (Geneva) Agr. Exp. Sta. Bull. 442. 1917. The Seed-Corn ^Maggot Phorhin fusciceps Zetterstedt The injury caused by the cabbage root-maggot is often augmented by the presence of a closely related species which has received the rather inappropriate common name given above. The seed-corn maggot is generally distributed throughout the United States and Canada and also occurs in Europe. In addi- tion to cabbage and related plants, it attacks sprouting seed corn, beans and peas, and has been recorded as feeding on seed pota- toes and onions. The food of this species is not confined to vege- INJURIOUS TO CABBAGE AND RELATED CROPS 37 table matter, for at the time (if tlie great outbreak of migratory locusts in the West, the maggots attacked the eggs of these grasshoppers which then occurreci in great abundance. Gen- erally, however, the maggots feed on planted seeds which have softened in germination or from decay. They are sometimes very destructive to seed beans especially in cold, wet, backward seasons. In some cases more than half of the crop is destroyed over large areas in this way. The maggots burrow into the seed-leaves, destroying them, and then mine into the stem. Some of the injured beans fail to germinate; more often, however, the seed-leaves pushup through the soil, but as the bud is injured the plants fail to leaf out. The flies of the seed-corn maggot closely resemble those of the cabbage root-maggot, but the males may be distinguished by lacking the tuft of hairs on the under side of the base of the hind femur, and by having on the under side of the hind tibia a row of short spines (Fig. 2() C). The females of the two species are indistinguishable. As far as known, the life histories of the two species are very similar. Control. The seed-corn maggot, when attacking cabbage and related crops, may be controlled by the means suggested for the cabbage root-maggot. The injury to germinating beans may be pre- vented in large measure by planting the seed shallow in cold wet seasons. Beans planted in this way come up more quickly and, being in a vigorous condition, are able to outgrow any slight injury to the seed-leaves. The Western Radish ]\Iaggot Phorbia planipalpis Stein On the Pacific Coast the cabbage root-maggot is replaced by a closely related species with similar habits. The maggots of this 38 MANUAL OF VEGETABLE-GARDEN INSECTS fly liave been found iiifestiiiji- radish, cabbaj2;e, cauliflower, ruta- baga and turnip and have also been observed abundantly in the pods of lupine and field peas, destroying the seeds. The fly closely resembles the adult of the cabbage root-maggot. The male is ^ inch in length and the female about ^ inch. The insect hibernates both as adults and as puparia. The female deposits her white, elongate, slightly curved eggs, about P6 inch in length, singly or in loose masses on the roots or on the leaves near the crown. On hatching, the maggots bur- row into the radish roots rendering them unfit for food. ]\Iany maggots often infest the same root and sometimes kill the plant. The full-grown maggot is :j to f inch in length and is whitish or yellowish in color. The body tapers toward the head and is truncate behind. When mature the maggots transform to puparia either within the root or in the surrounding soil. The pupariura is about ^ inch in length and brownish in color. There are said to be several generations annually. A satisfactory method of control does not seem to have been worked out. Reference Essig, Insects of California (Ed. 2), pp. 3.3G-.339. 1915. The Harlequin Cabbage Bug Murgantia histrionica Hahn In the last half century the harlequin cabbage bug has spread from its home in Central America and Mexico northward to Nevada, Colorado, the southern part of Illinois, Indiana, Ohio, Pennsylvania and New Jersey and to Long Island, New York. It also occurs in California. Except in the extreme northern part of its range, it is a most destructive enemy of cabbage and related plants. It is also known as the terrapin-bug, fire-bug and calico-back. When food is abundant, it usually confines its attacks to plants belonging to the mustard family, being es- INJURIOUS TO CABBAGE AND RELATED CROPS 39 pecially fond of horse-radish, but when its favorite food plants have been destroyed the bugs will migrate to adjoining fields and feed on almost any plant available. Eggplant, asparagus, potato, tomato, okra, bean, beet and even nursery stock are sometimes severely injured under such circumstances. The in- sect also breeds on a large number of wild plants belonging to the mustard and caper families. The harlecjuin bug hibernates as an adult under rubbish ; in southern Florida the insect remains on the food plants during the winter, but its ac- tivities are more ^ or less retarded. As soon as spring '-:'., opens, the adults emerge from win- ter quarters and congregate on any cole plants avail- able. The female deposits her eggs on the underside of the leaf in masses each con- taining normally twelve eggs ar- ranged in two rows of six each. The females that have wintered over are more prolific than those of later generations ; they are each capable of laying about one hundred eggs. Females of the next generation lay on an aver- age only about seventy-five eggs. The egg is oV inch in length by 3V inch in width, cylindrical, truncate at each end ; the upi)er end is provided with a circular lid which is pushed ofi' at the time of hatching. The egg is pearl-gray or pale yellow, Fig. 33. — Egg-clusters of the harlequin cabbage buf: on the underside of a leaf ( X 2) . 40 MANUAL OF VEGETABLE-GARDEN INSECTS Fig. 34. — Eggs of the harlequin cab- bage bug, side view (X5). with two black bands, one broader and more distinct near the top and the other near the bottom. There is a black spot just above the lower band and sometimes the eggs are irregularly blotched with black. The cap of the egg has a semicircular black mark inside the marginal ridge. The egg has a striking resemblance to a small white keg with black hoops, the spot on the side suggesting thebunghole (Figs. 33 and 34). The eggs hatch in four to eleven days, de- pending on the temperature. The newly hatched nymph is pale green in color with black markings. The insect passes through five nymphal stages and acquires wings at the fifth molt. In its later stages, the nymph is brightly colored — black, orange or yellow, and red. About two months after hatching, the nymphs reach maturity and transform to adults. The adult (Fig. 35) is about f inch in length, mottled red, black and yellow or orange. In all stages the bugs have a disagreeable odor and are distasteful to birds. In feeding, both adults and nymphs puncture the plants and suck out the juices. A half dozen bugs are enough to kill a cabbage or turnip plant. The severity of the injury inflicted seems to be out of proportion to the amount of food wit|idrawn from the plant and is supposed to be produced by a poison which the insect injects while feeding. Injured cabbage plants wither and turn brown as if scalded. The crop in whole fields is often com})letely destroyed. Many gardeners have been deterred from planting cabbage and collards because of the ravages of this pest. Fig. 35. — The harlequin cub- bage bug, adult ( X 3|). INJURIOUS TO CABBAGE AND RELATED CROPS 41 Control. Both the nymphs and adults of the harlequin cabbage bug are very resistant to contact insecticides. In fact it is prac- tically impossible to kill them in this way without injuring the plants. Loss may be prevented in large measure by practicing clean cultural methods of farming. After the crop has been harvested, all cabbage stumps and other refuse should be plowed under or destroyed in some other way. Hibernating shelter in the form of overgrown fence rows or patches of rank weeds should be reduced to a minimum. It is sometimes advised to leave a few piles of rubbish in the field in the fall as traps for the hibernating bugs. After they have collected in such shelter, the rubbish should be burned. Very effective work can be carried on against the bugs in the spring by the use of trap crops. Kale, mustard and rape are often utilized for this purpose. If a few of these plants are sown so as to be available for food before the crop it is desired to protect is up, the insects will congregate on these plants where they may be killed by spraying with pure kerosene or in some other way. In the fall it is a good plan to leave a few cabbage, turnip or kale plants after the remainder of the field has been cleaned. The bugs will collect on these plants where they may be easily de- stroyed before going into hibernation. The destruction of the adults early in the spring is the most important measure for the control of the insect ; if this work is done with thoroughness the crop will remain relatively free from attack for the remainder of the season. If the bugs are not destroyed in early spring, the only recourse is to hand-pick them into pans of kerosene — a tedious and laborious operation. References N. r. Dept. Agr. Eiit. Circ. 8. 1904. U. S. Bur. Ent. Circ. 103. 1908. Smith, .Jour. Ec. Ent. 2, pp. 108-114. 1909. 42 MANUAL OF VEGETABLE-GARDEN INSECTS The Green Soldier-Bug Acrosternum hilaris Say In the northern states the fruit of peach, apple and pear is occasionally seriously injured by the punctures of a large green stink-bug. The insect is widely distributed throughout the United States and Canada and southward to the West Indies and Brazil. It has also been recorded as attacking cabbage, bean, pea, corn, okra, tomato, eggplant, turnip and mustard, and it also feeds on a large number of shrubs and trees. The insect has been carefully studied as a fruit pest in Ohio. The green soldier-bug (Fig. 36) is from ^ to f inch in length, oblong, oval, bright green in color with the edges of the head, thorax and abdomen narrowly bordered with yellowish or reddish. The winter is passed by the adults hidden away in dry sheltered places, often under fallen leaves. The bugs emerge about the middle of May and egg-laying begins about the first of June continuing until the middle of July. The eggs are about iV ii^ch in length, oval, largest toward the top which is provided with a small circular cap, surrounded by a single row of about sixty-five club-shaped spine-like processes. The eggs are usually light yellow in color but are sometimes light green. Just before hatching, they become pinkish or reddish. They are attached to the leaf by one end and arranged in clusters of twenty to fifty. Each female usually lays two batches of eggs and a few may lay a third. The first batch is usually the largest and the last very small. The eggs hatch in about a week and the young nymphs remain in a c()nii)act cluster near the egg- FiG. 36. — The green soldier-bug (X If). INJURIOUS TO CABBAGE AND RELATED CROPS 43 shells till after the first molt. They are about xV inch in length, with the head and thorax brownish blaek and the abdomen marked with transverse black and light blue bands. In the course of its development the insect passes through five nymphal stages and acquires wings at the fifth molt. In the fifth stage the nymph is nearly ^ inch in length, with the head and thorax l)lackish marked with orange-yellow ; the abdomen is yellowish green. The nymphs require from seven to ten weeks to reach maturity and adults of the new brood begin to appear the last of July, but some of the nymphs do not reach maturity until the first of October. There is only one generation annually. A closely related species, Nezara vinduJa Linnseus, is some- times injurious to cabbage in the southern states. The plants are injured in much the same way as by the harlequin cab- bage bug. The adults so closely resemble those of A. hilar is that they are distinguished with difficulty. The most striking difference is that in the former there is a distinct, small black spot on the hind outer corner of the exposed part of each ab- dominal segment. In the latter these spots are very small and inconspicuous. The insect ranges from Virginia to Texas and northward to Indiana. It has also been reported as injuring tomato, sweet potato, okra, pepper, cotton and orange. No satisfactory method for the control of the green soldier- bugs, other than hand-picking, has been suggested. Reference Ohio Agr. Exp. Sta. Bull. .310. 1917. The Cabbage Leaf-Miners There are three species of flies, the maggots of which develop within the leaves of cruciferous plants, producing large whitish blotched mines. 44 MANUAL OF VEGETABLE-GARDEN INSECTS The imported tin nip Icaj'-vdner, Seapton/.ipa Jlaveola Meigen Originally a native of Europe where it is known as the turnip leaf-miner, this insect was introduced into the United States some time before 1891, and is now widely distributed, ranging from Alaska to New Hampshire and south to Kentucky and Virginia. Very little is known concerning its early seasonal history and the number of broods occurring annually has not been deter- mined. The parent fly ap- parently deposits her eggs on the upper surface of the leaves. On hatching, the young maggot burrows into the leaf and feeds just below" the upper epidermis, producing at first an irregular tortuous burrow w'hich is sud- denly widened to form a large blotch. The epidermis over the mine turns whitish and by a coalescence of several mines the A young^ cabbage leaf wholc leaf ma}' take ou this color (Fig. 37). The full-grown maggot is about ^ inch in length, whitish in color and cylindrical in form, tapering towards the head and bluntly truncate behind. When mature the larval skin hardens and turns reddish brown to form the puparium within which the true pupa is to be found. This trans- formation may take place in the mines but usually the puparia are found under rubbish on the surface of the ground. In Kentuckv the flies have been observed to emerge in late Fig. 37 showing the work of the imported turnip leaf-miner INJURIOUS TO CABBAGE AND RELATED CROPS 45 fall. The insect may, therefore, hibernate in the adult condi- tion. The fiy has an expanse of about j^ inch and its general color is brown, the antennae being yellow and the legs pale. This species has been recorded as feeding on cabbage, cauli- flower, radish, turnij), Iceland poppy, horse nettle and mouse- ear. The native cabbage leaf-miner, Scaptoniyza aduHa Locw This species is closely related to the preceding and has been reared in company with it. It injures the plant in a similar way. It is widely distributed from ]\Iaine to Florida and west to Illinois but is more abundant in the southern part of its range. The imported cabbage Icaf-Diiner, Scaptoinyza graviinuDi Fallen This European leaf-miner is now distributed in this country from New Hampshire to Texas. Its habits are similar to those of the two preceding species. In this country it has been reared from cabbage and in Europe it attacks several plants including chickweed, lamb's quarters, cockle and catchfly. There seems to be considerable doubt as to the determination of the three species just treated. Sturtevant, who has carefully studied these flies, does not believe that S. flacenla has been in- troduced into this country and is of the opinion that the studies on which the above account is based were made on a mixture of S. adusta and S. graminum. Control. Little is known as to the best measures for controlling these leaf-miners. Their injuries are rarely serious. It might be possible to kill the maggots in the mines by spraying with a strong mixture of nicotine sulfate and soap. 46 MANUAL OF VEGETABLE-GARbEN INSECTS References Ky. Agr. Exp. Sta. Bull. 40, pp. 46-51. 1892. Coquillett, Insect Life, 7, pp. 381-383. 1895. U. S. Div. Ent. Bull. 33, pp. 75-77. 1902. The serpentine leaf -miner, Agromyza pusilla Meigen The leaves of cabbage, turnip, radish and rape are sometimes disfigured by narrow, tortuous mines caused by a small, trans- lucent yellow maggot about ^ inch in length. This insect has also been found mining the leaves of potato, spinach, beet, water- melon, and pepper, as well as many wild and f,)rage plants. When mature, the maggots transform within the leaf into brownish puparia about ^ inch in length. In the summer about ten days are spent in this stage. The fly (Fig. 38) is from ^ to Yj inch in length, shining black and marked with yellow in a most variable way. The flies deposit their small, white, oval eggs, about yws inch in diameter, in the tissue of the leaf on the underside. The eggs hatch in three to eight days. The time required for each generation varies from twenty- three to forty days depending on the temperature. Breeding is continuous throughout the growing period and the number of generations depends on the length of the season. Reference Webster and Parks, Jour. Agr. Research, 1, pp. 59-87, 1913. Fig. 38. — The &y of the serpentine leaf- miner (X 20). INJURIOUS TO CABBAGE AND RELATED CROPS 47 The Falsi-; Chinch-Bug Nijsuis ericce Schilling Cabbage, cauliflower, radish and turnip are occasionally sub- ject to injury by a small grayish brown bug known as the false chinch-bug. This insect is widely distributed through- out the United States from California to New Hampshire and southward. It has been reported as most troublesome in the upper Mississippi Valley and in the western states. These bugs are very general feeders and sometimes injure beets, let- tuce, mustard, potatoes, corn, strawberry, cotton and even apple nursery stock and young grape vines. Seed-beets during the second year's growth are sometimes severely injured. The false chinch-bug hibernates as an adult in rubbish and under the leaves around the base of its food plants. The adult (Fig. 39) is about \ inch in length, grayish brown in color, sprinkled with blackish ; the head is marked with two longitudinal black lines and there is a transverse black band across the front of the prothorax ; the legs are yellowish brown. The bugs are most destructi^T in early spring when the adults come out of hibernation in great numbers and swarm on the young plants. In feeding, they puncture the leaves and suck out the sap, causing the plants to wilt, turn brown and die. The early spring and late fall broods deposit their eggs in cracks of the soil. The other broods place their eggs in the heads of various wild plants. The egg is described as beijig slender, cylindrical, irregularly wrinkled and tapering at both ends; it is vellow in color, orange-red at the anterior end. Fk;. 39. — The false chinch-bug, adult (X 11). 48 MANUAL OF VEGETABLE-GARDEN INSECTS The younfi; nymplis are yellowish markerl with indistinct loniijitiulinal dark lines. They feed almost exclnsively on weeds such as pepper-grass, shepherd's purse, Russian thistle and sage brush. The older nymphs are more distinctly marked with brown and reddish lines. When mature, the bugs scatter to all kinds of vegetation but in cases of drought are forced to congregate on cultivated plants. In Illinois the first brood nymphs mature in the latter part of May and the second in July. The broods overlap so that in midsummer all stages may be found together. In Kansas there are said to be at least five generations annually. In Colorado there is a smaller race of the species which bears the name Nysius mimdus Uhler. It has been recorded as very injurious to beets grown for seed. Control. Much can be done to prevent injury by the false chinch-bug by clearing the fields of all rubbish in the fall, thus depriving the bugs of hibernating shelter. This may be accomplished by burning over the fields. If the vegetation is not sufficient to carry the fire, straw may be scattered over the field. A gasoline torch may be used to kill the insects where they have congregated on weeds or clumps of grass. The insects may also be killed by thorough spraying with "Black Leaf 40" tobacco extract, 1 pint in 100 gallons of water to which 10 pounds of soap have been added. Burlap shields made sticky with a coat of crude petroleum are sometimes used to capture the bugs on plants that cannot be sprayed. References Riley, .5th Rept. Ins. Mo., pp. 111-114. 1873. Osborn, Rept. U. S. Ent. for 1887, p. 162. Forbes, 23rd Rept. 111. State Ent., pp. 117-118. 1905. U. S. Farm. Bull. 762. 1916. INJURIOUS TO CABBAGE AND RELATED CROPS 49 The Cabbage Curculio Ceutorliynchiis rapcv Gyllenhal One of the minor pests of cabbage, cauliflower, kale, radish and horse-radish is a small ash-gray weevil about ^ inch in length. This beetle is a native of Europe where it has never attracted attention as an enemy of cultivated crops. It was apparently introduced into America in New England about the middle of the last century but is now generally distributed throughout the northern states from New York to Virginia westward to Nebraska and Colorado. It also occurs in Cali- fornia. The insect hibernates in the adult condition and the weevils appear in the field in early spring. They feed slightly on the leaves and also puncture the stems of their food plants, eating out a cavity as deep as they can reach with the beak. The female deposits her eggs singly in similar punctures in the stems. The tissue surrounding the egg-puncture becomes en- larged, forming a noticeable scar. The egg is about -^ inch in length, o\'al and shining white. The eggs hatch in about a week and the grubs, several of which may infest a single stem, hollow out the contents, often causing the plants to turn sickly and die. The full-grown grub is ^ to j inch in length, milky white with a brownish head. The larvse become mature in about three weeks, gnaw their way out of the stem and enter the ground wdiere at a depth of less than an inch they transform to milky white pupae in oval earthen cells. The beetles appear in about a week, or during the early part of June in the District of Columbia, and feed for a time on the stems and leaves of their food plants. Although the new brood of beetles appears at this early date, there is apparently only one generation annually. Larvae of the cabbage curculio have been found in the stem and crown of cabbage and cauliflower, the petioles of horse- 50 MANUAL OF VEGETABLE-GARDEN INSECTS radish and probably also infest the radish. Serious injury to cabbage and cauliflower plants in tlie hot-bed has been re- ported from Missouri. The beetles, however, prefer to deposit their eggs in the stems of wild pepper-grass, hedge mustard and shepherd's purse. When these plants are available for egg- laying, cultivated crops are not usually infested. In case wild plants are allowed to grow as a trap crop, they should be de- stroyed before the larvae reach maturity else they will merely serve to increase the abundance of the pest. Reference U. S. Div. Eiit. Bull. 23, pp. 39-50. fOOO. The Cabbage Seed-Stalk Weevil Ceutorhynchus quadridens Panzer Another European weevil closely related to the one last treated has been introduced into Massachusetts and Long Island, New York. On Long Island this weevil has proved a serious pest to cabbage grown for seed, hundreds of larvae being found in a single stalk, their presence causing the plants to wait and break over just before the seed begins to mature. Whole fields are often ruined in this way. The adult is slightly smaller than the cabbage curculio and the scales with which the body is covered are white intermixed with gray hairs. This weevil also infests kale and turnip and in Europe it is recorded as breeding in mustard, water cress, horse-radish and rape. No satisfactory method .of controlling this insect is known. The Red Turnip Beetle Entomoscelis adonidis Pallas In western Canada cabbages, radishes, turnips and beans occasionally have the leaves eaten by the larva? and adults of INJURIOUS TO CABBAGE AND RELATED CROPS 51 a scarlet beetle about \ inch in length, marked with three black stripes down its back and with a black patch on the prothorax. The insect is native to the region, where it fed originally on wild cruciferous plants, particularly the prairie wall-flower, but it is also found in Europe and Asia. The beetles deposit their red to dark brown, elongate-elliptical eggs, ^ to ^ inch in length, in large loose masses under clods of earth. The mature larva is black above and yellowish beneath, slug- shaped and about § inch in length. The larvae are said to feed mostly at night. When full-grown they burrow into the soil for an inch or so and there transform to bright orange pupjie about \ inch in length. The winter is passed in the egg stage in the ground. The beetles become noticeable in the fields in July and August and may be found as late as November. In Austria the winter eggs hatch in the early spring and the larvtne become full-grown in the latter part of April. The beetles appear in May and after feeding a few days go into aestivation in the ground where they remain till September or October. It is quite probable that when the habits of this beetle are thoroughly studied in America, its life history will be found to be much the same as in Europe. Spraying with arsenate of lead (paste), 2 or 3 pounds in 50 gallons of water, will kill many of the beetles and their larvae. Reference Fletdicr, Ropt. Ent. Canada for 1S92, pp. 10-13. Other Insects Injurious to Cabbage and Related Crops Corn ear-worm : 211 ' Southern corn root-worm : 222 Western corn root-worm : 225 Carrot beetle : 18.5 Tarnished plant-bug : 192 Sugar-beet webworm : 97 Southern beet webworm : 101 52 MANUAL OF VEGETABLE-GARDEN INSECTS Spinach aphis : 105 Western twelve-spotted cucumber beetle: 114 Belted cucumber beetle : 115 Garden springtail : 139 Potato aphis : 150 Common stalk-borer : 157 Bean thrips : 69 Garden flea-hopper : 77 Bean leaf -roller : 81 Onion thrips : 245 Argus tortoise beetle : 238 Spotted cutworm : 262 Well-marked cutworm : 263 Greasy cutworm : 265 Red-backed cutworm : 267 Dark-sided cutworm : 268 Striped cutworm : 270 Dingy cutworm : 271 Shagreened cutworm : 272 Granulated cutworm : 273 Clay-backed cutworm : 274 Variegated cutworm : 276 White cutworm : 278 Glassy cutworm : 279 Yellow-headed cutworm : 281 Spotted-legged cutworm : 282 Speckled cutworm : 283 Clover cutworm : 284 Bristly cutworm : 285 Army cutworm : 287 Fall army-worm : 292 Yellow-striped army-worm : 295 Striped blister-beetle : 302 Margined blister-beetle : 305 Ash-gray blister-beetle : 306 Black blister-beetle : 307 Spotted blister-beetle : 309 Immaculate blister-beetle : 310 Segmented black blister-beetle: 310 Potato flea-beetle : 314 Pale-striped flea-beetle : 321 Smartweed flea-beetle : 323 Striped cabbage flea-beetle : 324 Phyllotreta ramosa: 326 Four-spotted cabbage flea-beetle : 326 INJURIOUS TO CABBAGE AND RELATED CROPS 53 Hemiglyptus bnsnlis : 326 Sinuate-striped flea-beetle : 326 Western eal)bage flea-beetle : 327 Horse-radish flea-beetle : 328 Hop flea-beetle : 335 Root-knot nematode : 338 Millipedes: 342 Wheat wireworm : 348 Slugs: 354 Salt-marsh caterpillar : 359 CHAPTER III PEA AND BEAN INSECTS The more important insect enemies of the pea are of Euro- pean origin, while those of the bean are native. The seed weevils are, on the whole, the most troublesome pests of these crops, especially in the South. Peas are subject to widespread and destructive outbreaks of the pea aphis, especially where they are grown in large areas for the cannery. The seed-corn maggot occasionally causes serious damage to seed beans in seasons when the weather is cold and wet at planting time, and under similar weather conditions snails occasionally prove very destructive to the foliage. The Pea Weevil Bruchus pisorum Linnaeus The pea weevil is a native of the Old World but was intro- duced into America more than one hundred and seventy years ago. Peter Kalm records having found it in Pennsylvania, New Jersey and southern New York in 1748 and states that because of its ravages the settlers had in large measure been forced to discontinue the growing of peas. The insect is now widely distributed in most parts of the world where peas are grown. The economic importance of this pest is indicated by the statement of James Fletcher in 1903 that in Ontario alone the annual loss amounts to more than a million dollars. In this province many of the farmers had given up the growing 54 PEA AND BEAN INSECTS 55 of peas iK'cause of the depredations of this pest. A simiUir condition obtains in many parts of Germany. The pea ^vee^•il is less abundant in the northern part of its range and a large ])roiiortion of the seed peas planted in the South are obtained from the northern states, Canada and northern Europe. The pea weevil (Fig. 40) is considerably larger than the other species infesting the pea and the bean. It is about i inch in length, brownish in color mottled with gray, white and dark brown. There is a white spot on the middle of the hind margin of the prothorax and the wing-covers are crossed by a more or less indistinct whitish band towards the tip. The wing-covers do not extend to the tip of the abdomen and the exi)osed part is white with t\\'o large l)lack spots at the tip. When viewed from above, the ])roth{)rax has the appearance of being Fio. 40. — Tho pea slightly- notched on the sides. The base of ^^«^" (^ ^')- the antennse and the front and middle tlbioe and tarsi are reddish brown. There is a sharp tooth on the underside of the hind femur toward the tip. The wee\ils appear in the field about the time the peas are in blossom and after feeding slightly on the foliage, the female deposits her elongate, fusiform, yellow eggs singly on the sur- face of the newly formed pods. The egg is attached by a ^'iscid substance that on drying becomes white and glistening. As many as fifteen to twenty eggs may be laid on a single pod. The eggs hatch in about twelve days and the young larva bores into the pod. In case it does not happen to enter the pod directly over a young pea, it may burrow through the tissue of the pod as a miner until it reaches one of the seeds. The hole through which the young larva enters soon heals over and is indicated merely by a small brownish dot. The newly hatched larva is yellow with a black head. The prothorax is 56 MANUAL OF VEGETABLE-GARDEN INSECTS armed with a series of six strong spines and a pair of prominent toothed plates which point backward. These structures are apparently of use to the larva in making its way through the pod and in entering the pea. It also possesses three pairs of small slender legs. Soon after entering the pea, the grub molts and the spiny structures on the prothorax are lost. The larva becomes proportionately shorter and thicker and lies normally in a curved position. It soon works its way to the center of the pea and there eats out a large cavity. When full-grown, it is about j inch in length, white in color, with brownish mouth-parts. The short stumpy legs are easily overlooked. In Italy the larva reaches maturity about forty days after hatching. It then cuts out a smooth round hole to the surface of the pea, leaving only the outer hull as a cover- ing. It lines the cavity with a paste-like substance, thus ex- cluding all excrement from its pupal chamber. The pupa is dirty wdiite in color. The insect remains in this stage from nine to seventeen days. Only one weevil is found in a pea. In the warmer parts of its range, many of the beetles emerge from the seeds soon after transformation but in the North a large proportion remain in the seeds until the following spring and are often planted with the seed peas. Weevils that emerge in the field hibernate in dry sheltered places and fly back to the pea fields the following spring. There is only one generation annually. In the case of small peas, the weevil destroys about one half of the contents, in larger peas about one third. Infested peas are not suitable for planting. Experiments in Kansas have shown that in a germination test only about 25 per cent of the infested peas w411 sprout. In a field experiment in which thir- teen varieties of peas were used, only 4.4 per cent came up and only 3.8 per cent produced fair sized plants. At the same time, 64 per cent of uninfested peas of the same varieties gave a good stand of strong plants. Experiments in Canada have PEA AND BEAN INSECTS ' 57 shown that in the case of small peas, infested seed produced only 13 to 20 per cent of plants which bore pods and in the case of large peas 16 to 28 per cent. References Costa, Insetti, etc., pp. 133-140. 1857. Rilev, 3rd Kept. Ins. Mo., pp. 44-50. 1871. Kan. Agr. Exp. Sta. Bull. 19, pp. 193-196. 1890. Chittenden, U. S. Dept. Agr. Yearbook for 1898, pp. 234-239. Fabre, Souvenirs Entomologiques, 8, pp. 23-47. Frank, Arb. Biol. Abt. Land. Forst. Wirths. Kais. Gesundheitsamte, 1, pp. 86-114. 1900. Fletcher, U. S. Div. Ent. Bull. 40, pp. 69-74. 1903. The Beax Weevil Bruchus obiectus Say Probably the bean weevil is a native of the Xew World. It was first described in 1831 from specimens collected in Loui- siana. It first attracted attention by its injuries in 1860 in Rhode Island. The insect is now widely distributed throughout southern Canada, the United States, Mexico, Central America, the West Indies and South America. It also occurs in the Mediterranean region, Persia, Indo-China, jVIadeira, the Azores and the Canaries. Its favorite food plant is the common kidney bean, Phaseolus vulgaris, but limas and cowpeas are sometimes attacked in the field, and in storage it will also attack the faba bean, peas, chick peas, lentils and the seeds of Lathyrus sativus. The bean weevil is a very serious pest in the South. It is not so destructive in the northern states and Canada and it is from this region that a large proportion of the seed beans are obtained. The bean weevil (Fig. 41) varies considerably in. size but averages about | inch in length. The general color is light brownish. The wing-covers are mottled with light brown, 58 MANUAL OF V EGET ABLE-GARDEN INSECTS Fig. 41. — The l^eaii weevil ( X 9) . dark brown, gray and black, arranged in narrow longitudinal stripes. On the middle of each wing-cover near the inner margin is a fairly distinct light gray longitudinal bar. The exposed tip of the abdomen, the base and last segment of the antenna^ and the legs, except the hind femora below, are dull reddish brown. The hind femur is armed on the underside near the tip with one large and two small teeth. The beetles appear in the field about the time the beans are in blossom and feed slightly on the surface of the leaves. In cool weather the beetles are sluggish, but in bright warm days they can take wing quickly and fly to a considerable distance. As soon as the pods become nearly full-grown but while they are still green, the females begin egg-laying. The female first gnaws a slit through the pod close to the ventral suture and by means of her extensile ovipositor then deposits a cluster of eggs on the inside of the pod. The hole made by the beetle in the pod does not heal over but persists as a discolored spot even in the dried pod. The egg (Fig. 42) is translucent white, elongate-ovate, and about -^ inch in length ; the surface is slightly roughened. The eggs are sometimes inserted through an opening in the pod where it has been injured or where it has split in drying. The time required for the hatching of the eggs varies considerably with the temperature but apparently has not been ac- curately determined for eggs laid in fresh pods. On hatching, the young larva bears little resemblance to the mature grub. It is white, the head yellow, the mouth-parts brown and the eyes black. Three pairs of distinct, slender functional legs are present and the body is clothed with long hairs which serve to keep the larva upright when crawling. Fig. 42. — Egg of the bean weevil (X 40). PEA AND BEAN INSECTS 59 The young larva crawls actively ahoiit until it finds a bean which it enters through a small round hole about y¥s inch in diameter. In about three days after hatching, the larva molts and assumes the general appearance of the mature grub. The legs, eyes and the long hairs on the abdomen are lost, the body becomes proportionately shorter and thicker and the grub assumes a curved position. The larva burrows diagonally into the bean a short distance and there eats out a large cell covered in part only by the thin semi-transparent outer coat of the bean. It then lines the cell with a yellowish white paste, thus excluding all excrement from the pupal chamber. The length of the larval stage varies greatly with the temperature, or from eleven to forty- two days. The full-grown larva is ^ to Y inch in length. The insect trans- forms to a white pupa within the cell and remains in this stage from five to eighteen days. Soon after transforma- tion, the beetle neatlv cuts out a Fig. 43. — Beans showing circular lid through the seed-coat of ^^'viR '' "''''^' ^"^ '^^ the bean and makes its escape (Fig. 43). The entire life cycle requires from twenty-one to eighty days. The beetles emerging in the field soon begin laying eggs for another generation. The number of generations that occur in the field depends on the temperature and the length of the season. Breeding is continuous in stored beans provided the temperature is sufficiently high. In the vicinity of Washing- ton, D. C, there are probably six generations annually. The number of weevils reared from a single bean depends on the size of the seed. In cases in which the beetles are allowed to breed in stored seed undisturbed, they often reduce the contents to a powdery mass held together by the hull. As many as twenty-eight weevils have been reared from a single bean. Weevily beans are unfit for planting. In a large proportion of 60 MANUAL OF VEGETABLE-GARDEN INSECTS such beans, the germ is destroyed and many of the others are so injured that they cannot produce healthy plants. References Riley, 3rd Rept. Ins. Mo., pp. 52-56. 1871. Lintner, 7th Rept. N. Y. State Ent., pp. 255-279. 1891. Fabre, Souvenirs Entomologiques, 8, pp. 48-65. Kan. Agr. Exp. Sta. Rept. 1889, pp. 206-210. Slingerland, Psyche, 6, pp. 445-447. 1893. Chittenden, U. S. Dept. Agr. Yearbook for 1898, pp. 239-242. The Broad Bean Weevil Bruchus rufimanus Boheman The broad bean weevil is similar to the pea weevil both in the form and general appearance of the beetle and in its life history. It is a troublesome pest in Europe, northern Africa, Syria and Persia and has been recently introduced into California. By preference it attacks the European broad bean or horse bean but will also breed in peas and certain species of vetch. In Cali- fornia the weevils appear in the field by the last of March. The beetle closely re- sembles the pea weevil, both in form and markings. The latter are, however, more diffuse and the black spots at the tip of the abdomen are indistinct or lacking alto- gether (Fig. 44). The tooth on the under- side of the hind femur is more obtuse than in the pea weevil. The female deposits her eggs on the outside of the bean pods, as many as thirty-four having been found on a single pod. The eggs are attached by a mass of sticky material. The egg is elongate-ovate, white to greenish yellow, smooth, a little over ^ inch in length and about one half as wide. The eggs hatch in twelve to fifteen days. The larvae leave the egg-shell through Fig. 44. — The broad bean weevil ( X 9) . PEA AND BEAN INSECTS 61 the side attached to the pod and soon find their way into the young beans. The point of entrance is indicated in the dried beans by a small black dot. The larva very closely resembles that of the pea weevil. It eats out a cell in the bean, its posi- tion being indicated by a transparent spot where the larva has eaten out the contents under the outer hull. In California the larvae begin to pupate about the first of August and transform to adults the same season. Hibernation usually takes place in the beans but if they are kept in a warm room, many of the weevils will emerge in storage. From one to five larvae may be found in a single bean. There is only one generation annually and the weevils do not breed in dried beans. Infested beans are lighter in weight and their value as food for stock is con- siderably lessened. Furthermore, the percentage of germina- tion even of beans containing only one larva is considerably less than that of uninfested seed, and of beans that have been injured by four or five larvae, only about one third will germinate. References Costa, Insetti, He (Ed. 2), pp. 269-273. 1877. Lintner, 7th Rept. N. Y. State Ent., pp. 279-285. 1891. U. S. Bur. Ent. Bull. 96, pp. 59-82. 1912. The Four-Spotted Bean Weevil Bruchus quadrimaculatus Fabricius This weevil breeds by preference in the seeds of the cowpea but in storage will also attack peas and beans. The species is distributed throughout southern Europe, Africa, the East Indies, South America, the West Indies, Central America, Mexico and the southern states. The four-spotted bean weevil (Fig. 45) is about | inch in length ; the head and thorax are black ; on the middle of the hind margin of the prothorax are two small spots of whitish pubescence. The markings of the wing-covers vary greatly but in typical specimens are brownish. 62 MANUAL OF VEGETABLE-GARDEN INJECTS black at the base and on each there is a large dark spot at the middle of the outer margin and another at the tip. The ex- posed tip of the abdomen is brownish, usually marked with two black spots. The antennse are black, reddish brown at the base. The legs are brownish except the basal two thirds of the hind femora which is black. Under cage conditions, the beetles have been observed to deposit their eggs singly on bean pods. The egg is oval, lemon-yellow and about -^ inch long by ^ inch wide. It is attached to the pod by a thin sheet of gelatinous substance which extends beyond the egg. Under cage conditions in New York, it required fifty days fqr the eggs to hatch. When breed- ing in dry beans, the eggs are glued to the surface of the seed and hatch in thirteen Fig. 45 — The four- ^^ twenty days. On hatching, the young spotted bean weevil larva borcs directly through the pod and attacks the seeds within, or when the eggs are attached to the seed, it enters directly under the egg-shell. The young larva closely resembles that of the pea weevil but differs in the armature of the pro- thorax. The full-groAvn larva is very similar to that of the bean weevil from which it may be distinguished by the larger area of black on the head just above the clypeus. The larva also injures beans in much the same way as the bean weevil. Pupation occurs within the seed. The rate of development varies considerably with the temperature and moisture. Several larvjie may infest the same seed and successive generations may be produced until the food supply is exhausted. References Slingerland, Psyche, 6, pp. 447-449. 189.3. Chittenden, U. S. Dept. Agr. Yearbook for 1898, pp. 245-248. PEA AND BEAN INSECTS 63 The Cowi'EA Weeml Bruchus chinensis Linnaeus Beans and peas in the southern states often become infested by the cowpca wee\'il. This insect is widely distributed through- out the tropics. In the United States its range extends nortli- ward to INIaryland and Iowa. The beetle (Fig. 46) is from -^^ to \ inch in length, brownish in color and may be distinguished from the other species in this country by the two ivory-white spots on the middle of the hind margin of the prothorax. The wing-covers are brownish, dark at the base and usually crossed with a darker band at the middle. In the male the antennae are pec- tinate. The female glues her eggs on the outside of the pods. The egg is ovate, flattened on the side of attachment, translucent, about -yV inch in length by -7^^ in width. The eggs hatch in four to ten days and the young larva bores through the pod and enters the seed. In the field, the larvae become full-grown in two or three weeks in midsummer. They closely resemble those of the bean weevil and several larvae may infest a single seed. Pupation takes place within the seed and transforma- tion to the beetle occurs in four or five days in warm weather. Breeding continues in stored seeds and six or seven broods may develop annually in the District of Columbia. Fig. 4G. — The rowpea weevil ( X 8) . References U. S. Div. Ent. Bull. S, pp. 24-27. 1897. U. S. Bur. Ent. Bull. 9G, pp. 83-94. 1912. 64 MANUAL OF VEGETABLE-GARDEN INSECTS The Control of Pea and Bean Weevils Seed infested by living weevils should never be used for planting, for it is in this way that many of the weevils gain access to the field. Neither is it good economy to use infested seed for planting in which the weevils have been killed, because the percentage of germination of such seed is low and the plants produced are weak and unproductive. In the case of the pea weevil and the broad bean weevil, species that do not breed in dried seed, the insects may be killed by holding over the seed until the second year before planting. The weevils will emerge in storage and, being unable to escape, will die without laying eggs. In the case of the bean weevil, the four- spotted weevil and the cowpea weevil, in which breeding con- tinues in the dried seeds, holding over the seed w^ould be use- less. Fumigation with carbon bisulfid is the most efficient and practicable method of killing the weevils in stored seed. To be most effective, the treatment should be made in the fall soon after harvesting. The seed is placed in a tight barrel or box to which a cover has been fitted as nearly air-tight as possible. Carbon bisulfid is used at the rate of ^ to 1 ounce to a bushel. In larger quantities in specially constructed fumigating cham- bers, the weevils can be killed by using carbon bisulfid at the rate of 3 pounds to 100 cubic feet. The liquid should be placed in some shallow dish like a pie tin on top of the seed. The fumigating box should then be covered tightly and fumigation should be allowed to continue for twenty-four to thirty-six hours. More satisfactory results will be obtained if the temperature is kept at 70 degrees F. or above. In fumigating, care should be taken not to smoke or to bring fire of any kind in contact with the gas, as the carbon bisulfid vapor is very inflammable. When there is only a small quantity of seed to be treated and when it is impracticable to fumigate, the weevils may be killed by suspending the seed in a bag in a kettle of cold water PEA AND BEAN INSECTS 65 and then heatinji; the water to a tenijierature of 140 deiirees F. The seed should then be si)i'ead out where it will dry quickly. The Bean Leaf-Beetle Cerotoma trifurcata Forster The bean leaf-beetle is a native American insect distributed from New York, southern Canada, ^Minnesota, ^Missouri and Kansas southward to Florida, Texas and New Mexico. It also occurs in Porto Rico. Its native food plants are the hog peanut, bush cloxer and tick trefoil. It has been reported as injurious to the bean, cowpea, pea, soybean, cultivated beggar- weed and corn. The insect hibernates in the adult stage and in the South the beetles appear in the field in April, in the District of Colum- bia the middle of jNIay, and in the more northern part of their range not until the last of June or the first of July. The beetle (Fig. 47) is about -j inch in length, yellowish to reddish in color ; the head is black and each wing-cover has a black band running around its base and extending backward close to, but separated from, the margin nearly to the tip. Near the inner margin is a row of three black spots, larger in front and smaller behind. The antennae are yellowish toward the base and darker toward the tip. The legs are marked with black and yellow, the hind pair being the darkest. The beetles usually rest on the underside of the leaves where they are easily overlooked. In feeding, they eat out holes in the leaves and when abundant leave only the larger veins. The plants are often defoliated and the crop is ruined. The beetles do not take wing readily but when disturbed fall to the ground. The female deposits her eggs in clusters in the soil at the base of the plants. Clusters of over forty have been observed but the average is about twelve. The egg is about -^ inch in length, elliptical in outline, orange in color and the surface is G6 MANUAL OF VEGETABLE-GARDEN INSECTS sculptured with rows of hexagonal pits. One female has been known to deposit 795 eggs, but this is undoubtedly far above the average. The female continues to lay eggs for nearly a month. The eggs hatch in about eighteen days in the spring and in the summer in five to eight days. The larvae feed on the roots, the stem underground, and are particularly fond of the bacterial nodules found on the roots of leguminous plants. The full-grown lar\'a is -^ inch in length, white in color, with the head, cervical and anal shields dark. The larva becomes mature in three weeks in summer to six or more in the fall, transforms to a white delicate pupa in a small earthen cell in the ground and in about a week the transforma- tion to the adult takes place. In the North there is only generation a year. In south probably three. Fig. 47. — The bean Icri- beetle (X 3i). one Virginia there are two, and farther Control. The beetles may be killed by spraying the vines with arse-* nate of lead (paste), 4 pounds in 100 gallons of water, taking care to apply the spray to the underside of the leaves. The application should be made at the first appearance of the beetles before they have had time seriously to injure the plants and in order to destroy the females before they have laid their eggs. In the home garden, the beetles may be collected by hand but spraying is the more convenient and practical treatment. References Chittenden, U. S. Div. Ent. Bull. 9, pp. G4-71. 1897. McConnell, Jour. Ec. Ent., 8, pp. 261-266. 1915. PEA AND BEAN INSECTS 67 The Grape Colaspis Colas pis brunnea Fabricius This insect occasionally riddles the foliage of beans with holes, its work being similar to that of the bean leaf-beetle. The foliage of beet, cantaloupe and potato is sometimes eaten. The beetle is about ys i'^ch in length, uniform yellowish brown with the wing-covers distinctly striate. The larvae are found on the roots of strawberry, corn, timothy and other grasses. They are white, with the head and cervical shield yellowish and |- to 1^ inch in length. They reach maturity in May or June and pupate in earthen cells. The beetles are common ■ throughout the summer but are most abundant in June and July. The insect is generally distributed throughout the northern states and Canada east of the Rocky Mountains. In case the beetles become sufficiently abimdant to threaten serious injury, they may be poisoned by spraying the plants with arsenate of lead (paste), 2 or 3 pounds in 50 gallons of water. References Forbes, 1.3th Rcpt. Rtcatc Ent. 111., pp. 1.56-159. 1884. Forbes, 22ncl Rept. State Ent. 111., pp. 145-149. 1903. The Bean Ladybird Epilachna corrupfn Mulsant In the foot-hills from Wyoming through Colorado to Arizona, New Mexico, Texas and ^lexico, bean plants are sometimes seriously injured by one of the ladybird beetles. The insect also occurs in western Kansas. The bean ladybird passes the winter in the adult condition. In New Mexico the beetles appear in the field from early June to the middle of July. The beetle (Fig. 48) is about -j inch in 68 MANUAL OF VEGETABLE-GARDEN INSECTS length, o\al in outline, strongly convex and pale yellowish to brownish orange in color. The eyes are black and each wing- cover is marked with eight small black spots arranged in three transverse rows. The beetles feed on the foliage, eating out holes in the leaves, and deposit their elongate, yellowish eggs in clusters of forty or more on the underside of the leaves. Each female lays on the average nearly 300 eggs and one beetle was observed to lay over 750. The egg is about -^ inch in length, oval and yellow in color. The eggs hatch in four to nine days and the young larvae begin feeding on the underside of the leaves, skeletonizing them. The larva passes through four stages in the course of its development and becomes full-grown in two or three weeks. It is then about f inch in length, light yellow in color and clothed with stout branched spines. When mature it attaches the tip of its body to the leaf and transforms into a yellow pupa about -g- inch in length. The pupal period occupies from three to five days. The entire life cycle is completed in three to four weeks in New Mexico. In Colorado there is said to be but one generation annually ; in New Mexico there are two. The seasonal history of the bean ladybird has been studied most carefully in New Mexico. In that region the over- wintered beetles lay eggs from the middle of June to the first of August. The larvse of the first brood are found until the latter part of August, producing a brood of beetles some of which may hibernate. The earliest beetles to mature of the second brood begin laying eggs about the middle of Jul\' and continue till the end of the season. The two generations thus overlap during July and August and it is at this time that the larvse and beetles are most abundant and destructive. In Fig. 48. — The bean ladybird (X 3). PEA AND BEAN INSECTS 69 many cases the plants are completely defoliated and the entire crop is ruined. The beetles also have the habit of eating into and destroying the green pods. Control. The bean ladybird may be controlled by spraying the plants with arsenate of lead (paste), 2 to 4 pounds in 50 gallons of water. In localities in which the beetle is annually destruc- tive, much injury may be avoided by planting early so that the crop will mature early enough to escape serious injury, (lean farming to eliminate hibernating shelter for the beetles and a proper rotation of crops will accomplish much to prevent loss. In the home garden, hand-picking the beetles and eggs may be practiced to advantage and the larvse may be brushed oflF on the hot ground during the heat of the day where they will perish without regaining the plant. References Col. Agr. Exp. Sta. Bull. 19, pp. 25-27. 1892. N. M. AgT- Kxp- f>ta. Bull. lOG. 1917. The Beax Thrips Heliothrips fasciatus Pergande In California beans are subject to serious injury by a species of thrips, the mature female of which is about -^ inch in length, with the head and body black. The narrow front wings are black, white at the base and with a white band towards the tip. The antennje are black and white and the wings are fringed with long white hairs. The male is somewhat smaller. Both young and adult thrips are found working on the leaves, stem and pods of the bean, which they injure by piercing the tissues with their sharp mouth-parts and then suck out the juices at the point of injury. The injured leaves turn yellowish 70 MANUAL OF VEGETABLE-GARDEN INSECTS or white, dry up and die. In some cases the plants may be entirely killed. The bean thrips has been most injiu-ious in California but also occurs in Idaho, Utah, Nevada, Arizona and Tennessee. It is not confined to the bean but attacks many other plants, including beet, cabbage, lettuce, radish, potato, tomato, pea, pear, alfalfa and cotton. Among weeds, its favorite food plants are spiny lettuce, sow thistle and wild heliotrope. The bean thrips hibernates in the adult condition on the underside of the leaves of nasturtium, beet, wild heliotrope and many other plants. It is also found in dried leaves and under rubbish. In the warmer parts of its range, the insect is active throughout the greater part of the year, feeding being interrupted only for a short time during cool spells. On emerg- ing from hibernation, the adults immediately seek their food plants and after feeding for a short time the female deposits her minute translucent white, bean-shaped eggs, about ywu inch in length in the tissue of the leaves, in the veins and even in the stems of beans. The eggs hatch in thirteen to eighteen days. The newly hatched nymph is about -g-^ inch in length and uniform translucent white in color with the eyes reddish. In the second stage, the nymph is about ^ inch in length with the head and prothorax light yellow and w^ith the re- mainder of the body translucent white and stained on the side with crimson. During the first two stages, the nymphs feed on the leaves in the same way as the adults. When full-grown, they desert the plants and hide in rubbish and in cracks in the ground and there molt. In the third stage, the nymph or so- called prepupa is slightly smaller than in the preceding stage and the wing-pads are well developed. The insect does not feed in this stage but in from one to six days, depending on the season, it molts again. In the fourth stage or so-called pupa, the nymph is ^ inch in length, yellow or orange in color, marked with crimson on the sides and across the abdomen and PEA AND BEAN INSECTS 71 the antennpe are carried back over the head. In this stage the insect is shiggish and takes no food. In four to fourteen days, dependino; on the season, the nymph transforms to the adult. In California there are seven generations a year, the first and last being small. In the early part of the season the thrips are most abundant on their wild food plants. They do not become abundant on beans until later in the season, although a few may be found on this crop from the time it first comes up. Control. The injury caused by the bean thrips may be lessened by clean cultivation to destroy the weeds on which the insect breeds. Early planting and thorough cultivation will tend to produce a rapid and healthy growth and render the plants more able to withstand injury. In the garden the thrips may be controlled by spraying with "Black Leaf 40" tobacco ex- tract, 1 part in 800 parts of water in which enough soap has been dissolved to produce a good suds. Reference U. S. Bur. Ent. Bull. 118. 1912. The Pea Aphis Macrosiphum pisi Kaltenbach Without doubt the most serious insect enemy of the pea is this large green plant-louse. The insect was undoubtedly intro- duced into this country from Europe. Although there is evi- dence that it was present here as early as 1878, it did not attract attention as a pest until 1899 when there was an extensive and highly destructive outbreak in the Atlantic states, most serious in \'irginia, INIaryland, Delaware and New Jersey. The losses occasioned by this insect in the Atlantic states during the years 1899 and 1900 have been estimated at .$7,000,000. While the pea aphis has not maintained this rate of destructiveness in 72 MANUAL OF VEGETABLE-GARDEN INSECTS recent years, it is still the most serious insect pest with which pea-growers have to contend. In England the pea aphis has been known as a pest since the early part of the nineteenth cen- tury. It received the scientific name under which it is now known in Germany in 1843, although it is quite probable that it had been more or less imperfectly described previously. The pea aphis occurs generally throughout Europe and has been introduced into British India and South Africa. In North America it is widely distributed throughout the United States and Canada, being most abundant in the East, but has been reported from Colorado, Texas, New Mexico, Arizona and the states on the Pacific Coast. In addition to the pea the insect attacks red clover, crimson clover, white clover, alsike, vetch, sweet pea, sweet clover, bush clover, alfalfa and lentil. It als:) occasionally infests shepherd's purse. In Europe the aphis has been recorded as feeding on several other leguminous plants. The pea aphis usually passes the winter on clover and breed- ing is resumed on this plant in the spring. At this time the aphis shows a decided preference for crimst)n clover on which it multiplies rapidly. In Virginia about the last of April or the first of May, winged aphids are produced that migrate to peas. These migrating forms are all females that reproduce by giving birth to living young without being fertilized. These winged viviparous females (Fig. 49) are i to ^ inch in length, pea-green in color, with the tip of the cornicles, tip of the tibife, and the tarsi black. The eyes are red. The antennfc are slightly longer than the body. The winged forms settle on the pea plants, usually on the stem, and begin to give birth to living young. In the course of its development, the young aphis passes through four immature stages, molting four times, and at the last molt becoming adult. On the average it requires about ten days for the young aphis to reach maturity, and when about twelve days old it begins to produce living young. Re- PEA AND BEAN INSECTS 73 Fig. 4n. — Winged vivii)ar()U,s female of the pea aphis ( X 5). production continues for an average peri(^d of eighteen days at the rate of one to eleven a day. The number of yoinig produced by a single female averages eighty. Both wmged and wingless forms are pro- duced, the relative proportion of the two varying with the seastm and with the crowded condition of the plant. The wingless form (Fig. 50) re- sembles the winged vi\'iparoiis female in color. The stems become covered with the lice, and the leaves, blossoms and pods are soon attacked. In- fested leaves become slightly thickened and curled, infested blossoms arc blasted and injured pods are stunted, deformed and rendered worthless. Badly in- fested plants take on a sickly yellowish appearance and may be killed outright. Sometimes whole fields are destroyed in this way. In such cases, the ground has a whitish appearance from the cast skins of the plant lice. ^Yheneve^ the plants become crowded, winged forms are produced that migrate to other parts of the field or to other food plants. In Virginia it has been found that while breeding is more or less continuous throughout the year on clover, the insect migrates more or less regularly between its other food plants. Fig. 50. — Wingless Peas are infested from April to the first of July viviparou-s female , p,, i.i- -j-xuu pea aphis (X 5). '^^'^i^'ii many oi the plant-lice migrate to bush clover, sweet clover, alfalfa and the clovers. Peas again })ecome infested in August and the plant-lice remain here until the advent of cold weather when they return to clover. Counting from the first-born of each brood, twenty or twenty- 74 MANUAL OF VEGETABLE-GARDEN INSECTS two generations of the pea aphis may develop annually in Vir- ginia. In Indiana breeding experiments have shown that counting from the last-born, thirteen generations are produced annually. The insect hibernates on clover either as mature viviparous females, winged or wingless, or in the cooler part of its range in the egg stage. Males and egg-laying females are produced late in the fall only. The male is usually winged, is considerably smaller than the viviparous female and has darker markings on the head, thorax and abdomen. Only a few wingless males have been observed. The egg-laying female is wingless, and much smaller than the wingless viviparous form which it resembles closely in color. The hind tibiae are con- siderably thickened basally and bear numerous sensoria. The winter eggs are usually found on red or crimson clover. The egg is about -is inch in length, elliptical oval in outline and pale when first laid, changing to jet black. The pea aphis is subject to the attacks of several parasitic and predaceous insects and particularly to a fungous disea'se that often destroys a large proportion of the lice. These natural enemies are most effective during the warmer part of the season and often nearly exterminate the lice locally on certain food plants. Means of control. As the pea aphis lives over winter and begins breeding in the spring on clover, especially on crimson clover, the presence of these crops in the near vicinity of fields of early peas is a menace to the latter. In such cases, when crimson clover is being grown for green-manure arid is seen to be infested, it should be plowed under before the migration of the lice to peas takes place, without waiting for it to reach its full growth. The ground should then be harrowed and rolled. In cases in which the clover is grown for hay, it might be well to sacrifice this crop in order to save the peas. Experience has shown that peas grown in rows about thirty inches apart are, as a rule. PEA AND BEAN INSECTS 75 less seriously infested than when they are sown broadcast or in narrow drills. When the peas are grown in rows, the lice can be controlled by spraying with "Black Leaf 40" tobacco extract, 10 ounces in 50 gallons of water to which 4 pounds of whale-oil soap have been added. A traction sprayer is used, fitted with nine nozzles and arranged to spray three rows at a time. One nozzle is directed downward and the other two nozzles throw the, spray slightly upward into the row. The pump should be able to give a pressure of 120 to 150 pounds when all nine nozzles are in operation. With this outfit it is possible to. work effectively on twelve acres of peas a day. In spraying for the pea aphis, it is important to begin early, soon after the winged forms from the clover appear in the field. If the work is started on time, it is usually possible to control the pest with two or three applications at intervals of about a week. In Maryland, Delaware and New Jersey, it was found that much loss could be avoided by raising the main crop of peas for the cannery early in the season before the aphis became abundant. At the time of the first serious outbreak of the pea aphis in this country, spraying machinery and insecticides were not as effective as those now on the market and spraying experiments at that time gave very unsatisfactory results. Methods were, therefore, devised for destroying the lice by mechanical means. The aphids were brushed from the plants to the ground during the heat of the day with pine boughs and a cultivator was immediately run between the rows. In this way many of the lice were either killed by the heat or buried in the soil. This method is now little practiced under commercial conditions but might be followed to advantage in the home garden. References Del. Agr. Exp. Sta. 12th Rept., pp. 169-186. 1900. Va. Truck Exp. Sta. Bull. 13. 1914. U. S. Dept. Agr. Bull. 276. 191.5. Smith, loth Rept. State Ent. Va., pp. 32-6.3. 1914-1915. 76 MANUAL OF VEGETABLE-GARDEN INSECTS Fig. 51. — Winged viviparous female bean aphis (enlarged). The Bean Aphis Aphis rumicis Liunseus This black plant-louse is widely distributed throughout the o'reater part of the subtropical aiul temperate regions of the world. Its summer food plants include a great variety of vegetable crops : beans, especially the broad bean, lima bean, beet, pea, celery, aspar- agus, orach, onion, leek, rhubarb and horse-radish. In England it has been reported as attacking turnip and parsnip. It is almost certain to be found in great abundance on nasturtium late in the season. Its common wild food plants are dock, burdock, lamb's quarters, shep- herd's purse and pigweed. The winter is passed in the egg stage on Evonymus, syringa, snowball and Deutzia. The egg is about -gV inch in length and shining black in color. The eggs hatch in early spring and the first generation develops on the tender foliage of these shrubs. When mature, the stem-mothers, as the aphids of the first gen- eration are called, give birth to living young, a few of which acquire wings. In the third generation a larger proportion Fig. 52. — Wingl;\ss vivip irons female bean aphis (X 20). PEA AND BEAN INSECTS 77 l)e('()me winged. The winged forms (Fig. 51) migrate to their summer food plants but the insect is capable of breeding the entire season on the plants on which it passed the winter. Throughout the summer the aphids reproduce parthenogenetically, all the individuals being females. Whenever the host plants become crowded, winged forms are produced that migrate to fresh feeding grounds. The full-grown wing- less viviparous female is about -^3 inch in length and blackish in color (Fig. 52). In the last nymphal stage of the winged form the abdomen is ornamented with five to seven pairs of white puh^erulent spots (Fig. 53). In the fall the winged forms fly back to their winter host plants and there produce yoimg that develop into wingless, egg-laying females. These are joined by winged males and after mating they deposit eggs in the crevices around the buds. The bean aphis can be killed by spraying with " Black Leaf 40" tobacco extract, 1 part in 100 parts of water in which enough soap is dissolved to give a good suds. Fiu. 53. — Lufit nymphal stage of the winged viviparous female bean aphis (enlarged). The Garden Flea-Hopper Haliicus citri Ashmead This small black plant-bug resembles the cucumber flea- beetle in size, form and in its habit of jumping when disturbed. The female is dimorphic. In one form the wings are fully devel()])ed and in the other they are short and lack the mem- branous portion at the end. The long-winged form (Fig. 54) is ^ij inch in length, black in color, with the thorax and wings covered with small tufts of yellowish scale-like hairs ; the tip of the cuneus has a white spot. The legs and antennae are 78 MANUAL OF VEGETABLE-GARDEN INSECTS Fig. 54. — The Rarden flea-hopper, long-winged female (X 16). pale, marked with black. The short-winged form (Fig. 55) is somewhat smaller and more ovate in outline. The front wings lack the membranous part, do not extend to the tip of the abdomen and are rounded behind, thus resembling the wing-covers of a beetle. The male (Fig. 56) is similar to the long-winged female but is much narrower. The garden flea-hopper is generally distributed through- out the eastern United States and Canada, and westward to Kansas and Utah. It feeds on a great variety of plants including bean, pea, potato, tomato, eggplant, pepper, beet, cabbage, pumpkin, cucumber, squash, celery, lettuce, sweet potato, corn, clover, alfalfa, sweet clover and cowpea. Among its wild food plants may be mentioned beggarweed, ragweed, pigweed, plan- tain, smartweed, thistle, mare's tail, burdock, wild lettuce, vervain, stick- tight, self-heal, mallow, aster, oxalis and convolvulus. The garden flea- hopper has also been recorded as a pest of chrysanthemums and smilax in greenhouses. The life history of the garden flea- hopper is very imperfectly known. It seems probable that hibernation takes place in the egg stage on some of its perennial host plants, but in the South it may pass the winter in other stages. In Fig. 55. — The garden flea- hopper, short-winged fe- male (X 14). PEA AND BEAN INSECTS 79 Illinois the insects appear the middle of May, become abundant in July and are found on the plants until October. The eggs have not been described. The nymphs are pale green in color with darker wing-pads. The insects are found in all stages on the upper side of the leaves. They feed by jiuncturing the leaves and suck- ing out the sap, thus causing small round yellowish or whitish spots. The number of gen- erations a year has not been definitely determined but there are probably more than one. Control. When present in sufficient numbers to warrant the trouble the garden flea-hopper may be destroyed by spraying with "Black Leaf 40" tobacco extract, 1 pint in 100 gallons of water to wliich 5 or () pounds of whale-oil soap have been added. Fici. oG. — Tho gurdeii fk'ii-hoijpor, male (X !()). Reference U. S. Div. Ent. Bull. 19, pp. 57-G2. 1899. The Pea ^NIotii Crapholtta nigricann Stephens The pea moth is a European insect introduced into Canada some time before 1893. It is now distributed throughout eastern Canada, being especially injurious in the maritime provinces, and was reported as destructive in Michigan in 1908. The moth has an expanse of about f inch. The front 80 MANUAL OF VEGETABLE-GARDEN INSECTS wings are brownish gray with a nietalHc reflection. Along the front border is a series of short, oblique white and dark lines. The liintl wings are black with a bronzy reflection ; the fringe is white. The moths appear in late June and early July and lay their eggs during the evening on the recently set pods, depositing from one to three eggs on each pod. The eggs hatch in about two weeks and the young caterpillars imme- diately burrow into the pods. They feed on the developing peas, gnawing out irregular cavities and often webbing them together. The full-grown caterpillar is slightly hairy, about ^ inch in length and yellowish in color, with a black head and brownish cervical and anal shields. Affected pods usually ripen prematurely. When the pods open, the caterpillar descends to the ground and spins a silken cocoon a short dis- tance below the surface of the soil. Here the winter is passed either in the larval or pupal state, observers differing as to this point. There is but one generation annually. Control. In Canada it has been found that both very early and late peas are less liable to injury than mid-season varieties. Pre- liminary experiments indicate that the pest may be held in check by spraying with an arsenical at the time the pods are forming and by two later sprayings at intervals of ten days. It has also been suggested that deep fall plowing of the infested land would destroy many of the hibernating insects in their cocoons. Under ordinary farm conditions in America, the most practical measure is to adopt a crop rotation in which peas do not follow peas. References Curtis, Farm Insects, pp. 348-350. 1860. Ritzema Bos, Tierisehe Sehadlinge und Niitzlinge, pp. 474-47.5. 1890. Fletcher, Repts. Ent. Canada for 1894, p. 187 ; 1895, p. 138 ; 1897, p. 194 ; 1900, p. 214. PEA AND BEAN INSECTS 81 TiiK Bkan Leaf-Uolleu Eudanius prole us Linnseus The bean leaf-roller is a tropical insect ranging from Para- guay through ^Mexico and the West Indies to Florida and northward sometimes to New York and Connecticut. In the United States it has proved injurious only in Florida. Its injuries are usually confined to beans, though it is recorded as feeding on cowpea, turnip, cabbage and several species of Desmodium. Sometimes entire fields have been ruined by the attacks of this leaf-roller. In the extreme southern part of Florida and in the tropics, the insect breeds continuously throughout the year. In northern Florida Fig. it undoubtedly hibernates in the pupal stage. The first brood of butterflies appears in March. The butterfly has an expanse of about If inches. The wings are dark chocolate brown ; the front wings, are marked with several angular silvery white spots. The hind wings are furnished with long tails, somewhat similar to those of the swallowtail butterflies (Fig. 57). The butterfly lays its eggs singly or in groups of four to six on the underside of the leaves. Occasionally three to four eggs are piled one above the other in a vertical column. The egg is nearly globular, slightly flattened at both ends and marked with a series of delicate longitudinal ridges. It is nearly -^ inch in length. When first laid, the eggs are glistening white, The bean leaf-roller butterfly (X U). 82 MANUAL OF VEGETABLE-GARDEN INSECTS gradually changing to a clear yellow. In summer the eggs hatch in four days and the young caterpillars immediately begin to eat out small i)atchcs in the surface of the leaves. Within a day after hatching, the larva constructs a retreat by folding over a flap of the leaf made by cutting along two lines converging from the margin. Within this retreat the larva lives, coming out only to feed. When about to molt, the edges of the retreat are sealed. In the third or fourth stage, the caterpillar constructs a new retreat by folding over a leaflet towards the middle"on the upper side. During the course of its development, the larva passes through five stages. The mature caterpillar is over 1^ inches in length. The head is brownish black and the body yellowish sprinkled with black, lighter below. The head is separated from the body by a distinct neck. The length of the larval period varies from two to three weeks. In Florida the life cycle requires about a month and there is, therefore, a possibility of eight or nine broods developing annually in that region. Under cage conditions, pupation occurs within the retreats and it is probable that this is the case in the open. The pupa is nearly an inch in length, greenish yellow at first, changing to shining brown. In two or three days it is covered with a white flocculent secretion. The pupal period occupies from six to ten days. Control. Experiments in Florida have shown that the caterpillars can be killed on beans by spraying with paris green. As this poison is likely to injure the plants, it would be better to use arsenate of lead (paste), -1 pounds in 100 gallons of water. References Scudder, Butterflies of Eastern U. S., 2, pp. 138G-1393. 1889. Fla. Agr. Exp. Sta. Bull. 45, pp. .^).5-60. 1898. PEA AND BEAN INSECTS 83 The Striped Green Bean Caterpillar Ogdoconta cinereola Giicnee Bean vines are frequently stripped of their foliage and pods by a slender green caterpillar. This injury has been reported from Florida, Mississippi and Maine. The insect is generally distributerl throughout Canada and the United States east of the Rocky IMountains. The light brown moth has an expanse of about an inch. The front wings are marked with a few wavv gra^•ish white cross Fic. .5s. — The moth of tho lines. ACTOSS the outer margin «trii.cKl green bean catcrpiUur is a broad, light brownish gray band. The hind wings are brownish gray (Fig. 58). The moths are on the wing from June to September but it is not known where the eggs are deposited. The full-grown cater- pillar is over one inch in length, pale green, striped with whitish and yellowish longitudinal lines. This insect is related to the ca})bage looper and like it, the caterpillar has the habit of loop- ing like a measuring-worm. When disturbed the larvae give a series of violent jerks and fall to the ground. Pupation takes place in the soil. The pale yellowish brown pupa is slightly less than ^ inch long. Knowledge of the life history of this insect is very imperfect and additional observations should be made whenever opportunity offers. When abundant, the caterpillars may be destroyed by spray- ing with arsenate of lead (paste), 5 pounds in 100 gallons of water. On snap beans tobacco dust may be used to drive them from the plants. Reference U. S. Div. Ent. Bull. 14 (old ser.), p. 21. 1887. 84 MANUAL OF VEGETABLE-GARDEN INSECTS The Gray Hair-Streak Uranotes melinus Hiibner One of the minor pests of the bean and pea is the shig-Uke caterpillar of a small, dainty butterfly, the gray hair-streak. It occurs throughout the United States, Central America, northern South America and the West Indies and is found rarely in southern Canada. It has been reported as injurious to beans or peas in New Jersey, Virginia, Maryland, Ohio and Colorado. In the South the caterpillars sometimes bore into cotton squares and okra pods and in the North they have been reported as feeding on the heads of the hop. Among wild plants, they feed on the following : Crataegus, St. John's- wort, hound's tongue, bush clover, loco-weed, tick trefoil, and Japan plum. The butterfly has an expanse of li inches. The upper surface of the wings is blackish tinted with blue-gray. The hind wings have near the hind angle a row of bluish spots, in the center of which is a large orange spot surrounding a small black one. On the outer margin there are in the male one, and in the female two, small tail-like processes. The under surface is gray with two blackish brown lines crossing each wing (Fig. 59). The butterflies are on the wing from May to September in the North and March to November in the South. The eggs are small and pea-green in color. Where they are deposited and the time of incubation have not been determined. The caterpillars bore into the pods of peas and beans and destroy the developing seeds. The full-grown caterpillar is green, about i inch in length, and slug-like in Fig. 59. • — The gray hair-streak butterfly (X U). PEA AND BEAN INSECTS 85 appearance. The chrysalis is iialved, and hangs freely, at- tached at the caudal end to a hutton of silk. The pupal period lasts from ten days to two weeks. In the North there are two, and in the South, three broods annually. If necessary, the caterpillars may readily be controlled by spraying with an arsenical. References Seudder, Butterflies of Eastern U. S., 2, pp. 850-855. 1889. U. S. Div. Ent. Bull. 33, pp. 101-102. 1902. The Green Clover Worm Plathypena scabra Fabrieius This insect is common throughout the eastern United States and Canada. Its favorite food plant is clover but occasionally the caterpillars defoliate peas, beans and lima beans. They are also found on tickweed, soybeans, vetch and strawberry. The moths have an expanse of 1 to 1-j inches, the larger specimens usually being males. The palpi form a rather prominent snout. \Yhen at rest, the wings are closely ap- pressed to the body. The front wings are blackish brown, the outer part of the wing in the female shaded with light gray and often with brown. The wing is crossed near the middle by a fine black line which is wavy and often very faint on the front half but straight and composed of raised black scales on the posterior half. At one quarter and at three quarters the distance from the base of the wing is a fainter wavy dark line and at one third the distance a raised black dot. Some females are marked with one or two longitudinal black dashes. The hind wings are blackish brown (Fig. GO). The moths emerge from hibernation in early spring. In Washington, D. C, they are on the wing in warm sunny days even in the winter. In that latitude there are three genera- 86 MANUAL OF VEGETABLE-GARDEN INSECTS tions annually ; the first brocid of caterpillars becoming mature about the middle of June, the second early in August and the third in late September or early October. The caterpillar is slender and loops with the front half of the body when walk- ing. In the next to the last stage, it is nearly an inch in length, pale green in color and striped lengthwise with fine white or cream-colored lines. In the last stage it is nearly uniform pale green, the stripes having become much less distinct. The caterpillars mature in about twenty-five days and then con- struct cocoons in leaves webbed together with silk within which S^[^^^^/^^^|^i| they transform to dark brown ^I^^^BBK^^^^ pupse about ^ inch in length. The ^^^^HWj^HBj^ moths emerge in eight days to two ^(Hpr^Hj^^ weeks and lay eggs for another ")rood. The egg is about -gV inch in Fig. 60. — The moth of the diameter, globular, flattened above green clover worm (X 11). . , . , i- • and with coarse ridges radiating from the apex. The eggs hatch in four to six days and the young caterpillars feed on the underside of the bean leaves, eating out irregular holes and when abundant stripping the plants of their foliage. Sometimes the caterpillars also eat holes in the pods. When attacking shell beans, the caterpillars may be poisoned by spraying the vines with arsenate of lead (paste), 2 pounds in 50 gallons of water, taking care to apply the spray to the underside of the leaves. On string or snap beans, tobacco dust or extract may be used. It has also been suggested that many of the caterpillars could be killed by spraying the un- derside of the leaves with a strong soap solution; References U. S. Div. Ent. Bull. 30, pp. 45-50. 1901. Conn. Agr. Exp. Sta. Rept. for 1908, pp. 828-832. PEA AND BEAN INSECTS 87 The Lima Bean Vine-Borer Monoptilota nubilella Hulst From Maryland to Florida and Alabama, pole varieties of lima beans are occasionally infested by a caterpillar that bnr- rows in the stalk, causing a gall-like enlargement which is about 1| inches in length by ^ inch in diameter. These galls may occur at any point from the surface of the ground to near the tip of the vine. The injury inflicted varies with the position of the gall and with the thriftiness of the vine. When the caterpillar enters a well-formed stalk, the plant is not seriously affected, but when the gall is fyrmed in small stalks near the tip, the terminal portion often wilts and dies or at least is not able to produce full-sized pods. The full-grown caterpillar is about f inch in length and of an unusual color for a borer, being a beautiful blue-green, tinged with pinkish above. When mature, it leaves the gall and pupates on or in the ground in an oval silken cocoon covered with particles of dirt. The pupa is dull olive-brown and a little less than ^ inch in length. Some of the moths may emerge the same summer and lay eggs for a second brood. The moth has an expanse of about | inch. The front wings are brownish gray shaded with whitish especially toward the base near the front margin and are marked with several small blackish streaks about one third the distance from the base of the wing. The hind wing is translucent white in the male and dark in female. Xo better treatment is known than to kill the caterpillars with a knife while still in their burrows. Reference U. S. Div. Ent. Bull. 23. pp. 0-17. 1900. Other Pea and Bean Insects Corn ear-worm : 211 Southern corn root-worm : 222 88 MANUAL OF VEGETABLE-GARDEN INSECTS Cabbage looper : 8 Garden webworm : 18 Seed-corn maggot : 36 Western radish maggot : 37 Harlequin cabbage bug : 38 Green soldier-bug : 42 Red turnip beetle : 50 Yellow bear caterpillar : 357 Salt marsh caterpillar : 359 Sugar-beet webworm : 97 Western twelve-spotted cucumber beetle : 114 Belted cucumber beetle: 115 Diahrolica connexa: 116 Diahrotica picHcornis : 110 Melon leaf-bug: 121 Southern leaf -footed plant-bug : 121 Melon aphis : 135 Garden springtail : 139 Potato aphis : 150 Common stalk-borer : 157 Spotted cutworm : 262 Well-marked cutworm : 263 Greasy cutworm : 265 Dark-sided cutworm : 268 Striped cutworm : 270 Dingy cutworm : 271 Granulated cutworm : 273 Clay-backed cutworm : 274 Black army-worm : 275 Variegated cutworm : 276 Gla&sy cutworm : 279 Clover cutworm : 284 Army cutworm : 287 Army-worm : 288 Beet army-worm : 294 Striped blister-beetle : 302 Margined blister-beetle : 305 Gray blister-beetle : 306 Ash-gray blister-beetle : 306 Nuttall's blister-beetle : 308 Spotted blister-beetle : 309 Two-spotted blister-beetle : 309 Western potato flea-beetle : 318 Pale-striped flea-beetle : 321 Red-headed flea-beetle : 323 I PEA AND BEAN INSECTS 89 Smartweed flea-beetle : 323 Western cabbage flea-beetle : 327 Desert corn flea-beetle : 334 Root-knot nematode : 338 Millipedes: 342 Slugs: 354 Red-spider : 351 Wheat wnreworm : 348 Sugar-beet wireworm : 349 CHAPTER IV BEET AND SPINACH INSECTS The insects attacking beet and spinach, as a rule, also feed on related wild plants, chiefly various species of Chjienopodium and Amaranthus. ]\Iany of these plants are common weeds and serve as centers from which infestation spreads to culti- vated crops. Over one hundred and fifty insects have been recorded as feeding on sugar-beets, about forty of which are considered as important pests. The sugar-beet is classed as a field crop and in this chapter only those insects are treated which have been found causing important injury to garden beets and spinach. The two principal insect pests of spinach are the leaf-miner and the aphis, their combined attacks often making the growing of this crop unprofitable in certain localities. The Spinach Leaf-Miner Pegomyia hyoscyami Panzer This troublesome pest of beets and allied crops is present in both Europe and America. In Europe the insect has been known for over a century and in this country it first attracted attention by its injuries about ISSO. It is now generally dis- tributed throughout the United States and Canada. The maggots infest the leaves of spinach, orach, beets, sugar-beets, mangels and chard. Its other food plants are lamb's quarters, and in the British Isles and Europe deadly nightshade, henbane, 90 BEET AND SPINACH INSECTS 91 Fig. G1. — The spinach leaf-minor, adult (X4). nettle-leaved goosefoot, common chickweed and lady's thumb {Pohigon u m pcrsicaria) . The flies appear in the fields in April or May. They are about \ inch in length, grayish in color and clothed with numer- ous black setoe ; the legs are yellowish with the tarsi blackish (Fig. Gl). The female deposits her eggs singly or in rows of two to five placed side by side on the underside of the leaves (Fig. 02). The egg is about ^V "^t-h in length, white, cylin- drical, and the surface is distinctly reticulated. The eggs are attached to the leaf by one side ; they hatch in four to six days and the young maggot works its way into the tissue of the leaf where it eats out a mine between the upper and lower epi- dermis. The mine is at first thread-like but is soon enlarged to form a blotch. Several maggots usually occupy the same leaf and their mines usually coalesce. In the course of its growth the maggot molts twice, thus passing through three stages. If the ff)od material in a single leaf becomes exhausted, the maggots may ; iG. 62. — Eggs migrate to another leaf in order to complete of the spinach ^hcir growth. In case the leaf dies, the mag- leaf-miner (X ,, , i-ii 31). gots are able to complete their development on manure or humus, according to observations made in Hungary. The larva becomes full-grown in a week to sixteen days. It is then ^ inch in length, white or yellowish with the hook-like mouth-parts black. The body 92 MANUAL OF VEGET ABLE-GARDEN INSECTS tapers towards the head and is obHquely truncate posteriorly. When mature, the hir\a usually deserts the leaf and enters the earth, where, at a depth of two or three inches, it changes to a brownish puparium, about ^ inch in length. Sometimes the puparia are founii in the dead and rotting leaves on the ground. The flies emerge in two weeks to twenty-five days and soon lay eggs for another brood. In central New York there are three generations and a partial fourth annually. The spinach maggot is most injurious to spinach and chard, and beets when used for greens. The injury to the leaves of beets, mangels and sugar-beets also decreases the size of the root-crop. When these crops are grown for seed, the quantity produced is often seriously lessened by the partial defoliation of the plants by the maggots. Control. No satisfactory method of preventing the damage by the spinach leaf-miner has as yet been devised. Clean culture and the destruction of the insect's wild food plants, lamb's quarters and other weeds will be of some value in decreasing the degree of infestation. In some localities growers avoid a bad infes- tation in spinach by growing the crop late in the fall and early in the spring. References N. Y. (Geneva) Agr. Exp. Sta. Bull. 99. 1896. Jablonowski, Tieresehen Feinde der Ziickerrube, pp. 303-315. 1909. Cameron, Ann. Appl. Biol., 1, pp. 43-76. 1914. The Beet Leafhopper Eutettix tenellus Baker In the western states from Idaho, Nebraska and Texas, westward to the Pacific and southward into Mexico, sugar- beets, table beets and mangels are subject to a disease known as curly-leaf, the exact cause of which is not fully understood. BEET AND SPINACH INSECTS 93 Diseased plants have the veins of the leaves enlarged, and the surface becomes warty, uneven, and the edges curl inward, bringing the under surface into view. The petioles are shorter and bowed outward. The leaves are more brittle than normal, although they have a leathery appearance. Young plants may be killed outright, others are badly stunted ; the sugar- content of the roots is lessened and there is an abnormal de- velopment of rootlets. Cross-sections of the root often show dark concentric circles from the darkening of the fibrovascular bundles. Frequently large fields of beets so affected are not worth harvesting and in many localities the growing of sugar- beets has been abandoned for this reason. When beets are grown the second year for seed, the presence of this disease greatly reduces the crop. The disease is transmitted by a small, creamy or greenish white leaf hopper, sometimes tinged with red, about ^ inch in length, both nymphs and adults being capable of infecting the plant on which they feed. This insect is a native of the same region where it feeds on several species of Atriplex and Russian thistle, sea blite and greasewood. Certain species of Atriplex seem to be its favorite wild food plants. The insect hibernates as an adult, appearing in the beet fields in late spring. Beet fields do not, as a rule, become infested by leaf hoppers that have hibernated in their immediate ^•icinity. Apparently the infestation comes from leaf hoppers that have developed on their wild food plants in desert regions and that have hiber- nated near their breeding groimds. In late spring these insects migrate in great swarms, passing over high mountain ranges and traveling to distances of several hundred miles. In the course of the migration, the leafhoppers settle in any beet fields in which the plants are in condition to serve as food. If the crop in a field is not up at the time of the flight, it is not likely to become infested from adjoining fields but may be 94 MANUAL OF VEGETABLE-GARDEN IN,SECTS attacked by a later flight if a second migration occurs. Injury by the leafhopper is hkely to take place in regions not infested the previous year and a season of severe injury may be fol- lowed by one in which practically no leafhoppers can be found. In most localities the disease is of a periodic nature, but in certain regions within the permanent breeding area infestation is almost sure to occur every year. In feeding, the insect punctures the leaf with the slender needle-like bristles of its beak and sucks out the juices of the plant, at the same time inoculating it with the virus of the disease. When disturbed, the leafhoppers spring quickly into the air and take wing, but soon alight seeking shelter on another plant. When on the wing they appear white. The female inserts her eggs their full length singly in the stems, midrib and petiole of the leaves and sometimes in the larger side veins. The eggs are pale, elongate, slightly curved and narrower anteriorly. Before hatching the growth of the leaf usually forces the eggs part way out of the tissue. The eggs hatch in about two weeks and the minute, nearly colorless nymphs begin feeding on the leaves down in the center of the plant. The older nymphs vary from creamy Avhite in color to nearly black, variously spotted and mottled with brown, buff and red. In about three weeks the nymphs become mature, having passed through five immature stages in the course of their growth. The eggs are laid during a considerable period, from late in June to the first of September in the northern part of the insect's range, but the greater number are deposited during the first half of July. Each female is capable of laying about 80 eggs. There is only one generation annually. The control of this leafhopper and the consequent elimina- tion of the curly-leaf disease is commercially unsolved. The adult hoppers are hard to hit and difficult to kill with contact insecticides and it is doubtful whether spraying would be com- mercially profitable. Something can be gained, however, by BEET AND SPINACH INSECTS 95 early planting:; aiul hy <;()()(1 care of the erop early in the season so as to get the plants well established before the hopj)ers make their appearanee in the field. References U. S. Bur. Ent. Bull. GG, pp. 33-52. 1909. U. S. Bur. Plant Ind. Bull. 181. 1910. Utah Agr. Exp. Sta. Bull. l.'>r>. 1917. The Lakger SiTrAR-BEET Leaf-Beetle Monoxia puncticollis Say In New ]\Iexico, Colorado and .Montana, sngar-beets are sometimes attaeked by the larvte and adults of this leaf-beetle, but it has not yet been reported as an enemy of table beets. Its wild food plants are sea blite, Russian thistle and salt-bush. Both larvie and adults feed on the leaves but the greater part of the injury is caused by the former. When dis- turbed they fall readily to the ground. The beetle occurs along the Atlantic and Gulf coast and westward to California, and north- ward through Colorado, Utah and Montana. It is ^ to ^ inch in length, and varies considerably in c )lor, from uniform dull yellowish brown to nearly black ; in some forms each wing-cover is marked with one or two more or less distinct dark stripes (Fig. 63). The insect hibernates in the beetle stage, appear- ing on its food plants early in the spring. The female de- posits her eggs, a little less than ^ inch in length, in irregular clusters of two or three to fort\' or fiftv on the leaves. These Fig. 6.3. — The larger sugar- beet leaf-beetle (X 4D- 96 MANUAL OF VEGETABLE-GARDEN INSECTS hatch hi about a week and the larvae begin feeding on the leaves. The young larva is about yV inch in length, dull gray, with the thoracic shield and the areas at the base of the tubercles dark brown. The larva becomes full-grown in nine or ten days. It is then about f inch in length, dark olive brown with the tubercles pale yellow. The larvae enter the ground for pupation and the beetles emerge a few days later. There are two generations annually. It has been observed in Colorado that the insect is most troublesome on beets grown on or near alkali ground. References U. S. Div. Ent. Bull. 40, pp. 111-113. 1903. Gillette, Kept. State Ent. Col., pp. 8-11. 1903. The Western Beet Leaf-Beetle Monoxia co7isputa Leconte This leaf-beetle ranges from California and Oregon east to the Dakotas and Kansas. It has been reported as injurious to beets and sugar- beets in California and Oregon. Both larvae and adults feed on the leaves, leaving only the larger veins. The beetle (F'ig. 64) is nearly ^ inch in length, yellowish brown ; the wing- covers are sometimes marked with small scattered black spots often arranged in rows. The beet leaf-beetles can be con- trolled by thoroughly spraying the plants with arsenate of lead (paste), 5 or 6 pounds in 100 gallons of water. Fk;. 04. — The western beet leaf-beetle (X 51). BEET AND SPINACH INSECTS 97 The Sucak-Bkkt Wkhwokm Loxoslege sticHcalis Linnaeus Although the sugar-beet webworm has attracted more atten- tion as an enemy of the sugar-beet, it also attacks a large num- ber of garden and field crops. It is widely distributed through- out Europe, Asia and North xA.merica and is particularly injurious in southeastern Europe. It did not attract notice in the United States until the beginning of the development of the sugar-beet industry. It has been destructive only in the Mississippi \'alley and westward to the Rocky JNIountains. In addition to the sugar-beet, it has been reported feeding on the following : pea, bean, potato, cabbage, onion, squash, pumpkin, cucumber, alfalfa and vari- ous grains and grasses. Its favorite wild food plants are pigweed (Ama- ranthus) and lamb's quarters. The winter is passed by the full- grown caterpillars in silken tubes in thp soil In latp snrinp- thev trans- Fig. 65. — The sugar-beet tne soil, in late spring ine\ irans webworm moth (x li). form within the tubes to yellow-brown puppe about ^ inch in length. In about eleven days the moths emerge. The moth has an expanse of about an inch. The front wings are smoky brown with faint darker markings, a straw-colored spot below the middle of the front margin and a similarly colored band along the outer margin. The hind wings are paler with two blurred bands (Fig. G5). The females deposit their pale, pearly green or yellow, oval eggs about ^ inch in diameter, singly (;r in overlapping rows of two to ten, usually on the underside of the leaves. The egg is flattened below and very convex above. Each female lays from 200 to 250 eggs. The eggs hatch in three to five days. The young whitish larvse with black heads feed at 98 MANUAL OF VEGETABLE-GARDEN INSECTS first on tlic soft tissues on the underside of tlie leaves. As they increase in size, they l)ecome yellowish ^reen in color with dark markings and consume almost the entire leaf. The caterpillars feed by preference on the older, outer leaves and do not attack the newer leaves at the center of the plant until the others have been consumed. Their feeding grounds are covered by a slight silken web. The full-grown caterpillar is about an inch in length, yellowish white with a broad black median stripe and a broader sub-dorsal stripe and marked with numerous piliferous spots surrounded by black rings. The larva becomes mature in about three weeks and constructs a silken tube in the ground within which it forms a cocoon and pupates. The winter cocoon is about three times the length of the larva and the summer cocoon only twice as long. There are usually three generations a year and in some cases a small fourth brood may occur. A few of the first, a considerable part of the second, and nearly all of the third generation cater- pillars do not transform till the following spring. The first brood are destructive while the sugar-beet plants are small and easily killed. At this time the crown of the plant is often attacked. When the later broods appear, the plants are larger and rarely killed outright but the size and sugar-content of the roots are greatly decreased by the defoliation of the plants. The third brood is the least injurious because the plants are more nearly mature and the brood is smaller. In some regions in which the sugar-beet is grown extensively, the caterpillars often occur in coimtless numbers and the moths attract attention by flying in clouds over the fields. Means of control. The sugar-beet w^ebworm may be controlled on sugar-beets by thorough spraying with .3 pounds of paris green in 100 gallons of water to which 6 pounds of whale-oil soap or 3 pounds of lime are added as an adhesive. About 100 gallons of the mix- BEET AND SPINACH INSECTS 99 ture should be applied to the acre and the application should be made as soon as possible after the caterpillars have hatched. The s{)ray should be applied with at least SO pounds' pressure. Recent experiments in Colorado and Kansas have shown that paris green applied in this way will satisfactorily control the webworm on beets and is much more effective than arsenate of lead. In some cases in which the ground is too wet for the use of a sprayer, paris green may be applied in the form of a dust at the rate of 2 to 4 pounds in 100 pounds of air-slaked lime. References Koppen, Die Shadlichcn Insokton Russlands, pp. 394-405. 1880. Rilev, Rept. U. S. Ent. for 1892, pp. 172-175. Col. Agr. Exp. Sta. Bui. 98, pp. 2-12. 1905. U. S. Bur. Ent. Bui. 109, pp. ,57-70. 1912. The Hawaiian Beet Webworm Hymenia fascialis Cramer In the southern United States beet leaves are sometimes skeletonized on the underside by a small, slender, pale green caterpillar which has received the rather inappropriate com- mon name given above. The insect ranges throughout the southern states westward to California. It is also generally distributed throughout the warmer parts of the Old World. Its habits and life history have been studied carefully in Hawaii. In that climate, breeding is continuous throughout the year. Its food plants include table beets, sugar-beets, Swiss chard, mangels and Amarantus gancjeticus, a Chinese pot- herb sometimes known as spinach. Among weeds, it feeds on purslane and numerous species belonging to Amaranthus and Chsenopodium. The caterpillars reach maturity in nine days to two weeks and then enter the ground a short distance, where they form firm, oblong earthen cocoons composed of silk and 100 MANUAL OF VEGETABLE-GARDEN INSECTS particles of earth. The pupa is f inch in length and pale brown in color. The moths emerge in a week or two. The moth has an expanse of about f inch. The wings are uniform blackish brown. The front wing has a broad translucent white band across the middle, not quite reaching the front margin. Two thirds the distance to the outer margin a wdiite bar extends halfway across the wing. The hind wing is crossed by a nearly even white band. The moths are shy and are usually to be found hiding under the leaves. In Florida they are often found in great numbers feeding on the nectar of catnip blossoms. The female deposits her minute elliptical flattened eggs, about 4V ii^ch in length, singly or in short rows on the underside of the leaves. The eggs hatch in about four days. The cater- pillars sometimes spin a slight web over their feeding grounds but more often feed openly. It is believed that in Hawaii from six to ten generations may be produced annually. This webworm can be controlled by spraying with arsenate of lead (paste), 2 pounds in 50 gallons of water, taking care to coat the underside of the leaves. Reference U. S. Bur. Ent. Bull. 109, pp. 1-15. 1911. The Spotted Beet Webworm Hymen a perspcctalis Hiibner The spotted beet webworm is widely distributed throughout the warmer parts of the world and in the United States is sometimes found out of doors as far north as Virginia. In greenhouses it often proves a troublesome pest on Alternanthera. In the open it sometimes becomes destructive to beets, sugar- beets and Swiss chard. The moth has an expanse of about |- inch. The wings are blackish brown shaded with clay-color, BEET AND SPINACH INSECTS 101 especially on the hind wings. The markings are translucent white ; on the front wing there is a narrow^ curved line near the base ; a nearly square patch at the middle near the front edge ; a line running from close to this to the hind margin, and two thirds the distance to the outer margin a white bar extends halfway across the wing. Across the middle of the hind wing is an irregular white band, narrower behind. The moth deposits her flat, oval, semi-transparent, greenish eggs, about ^V "i^ch in length, singly on the stems of the plant, usually near the base. The young larvae at first skeletonize the leaves but later devour the whole leaf. The full-grown larva is a little more than ^ inch in length, shining green and marked with rows of small black spots. Pupation takes place in a thin loose silken cocoon on the ground at the base of the plants. The pupal period occupies from one to three weeks, depending on the season. Under greenhouse conditions the life cycle is completed in two or three months. The spotted beet webworm may be controlled by the meas- ures suggested for the preceding species. References Davis, 27th Kept. State Ent. 111., pp. 103-106. 1912. U. S. Bur. Ent. Bull. 127, pp. 1-11. 1913. The Southern Beet Webworm Pachyzancla bipunctalis Fabricius In Georgia, Florida and Texas, this webworm has been re- ported as occasionally injurious to beets, cauliflower and cab- ))age. Its wild food plants include ragweed, spiny amaranth and Amarantus retroflexus. The insect ranges southward through the West Indies into South America and also occurs in South Africa. The caterpillars feed on the leaves of their food plants, folding and webbing them together with silken 102 MANUAL OF VEGETABLE-GARDEN INSECTS threads. The full-grown larva is a})out f ineh in length, dark, dirty green with the head and the sides of the cervictd shield dark brown. The surface of the body is semi-transparent and glossy in appearance. The caterpillars become mature in two or three weeks and transform to mahogany brown pupiie f inch in length. The posterior end of the body is prolonged into a bill-like process bearing four pairs of recurved hooks. The pupal period occupies about eight days in warm weather. The moth has an expanse of about an inch. The front wings vary from bufl' to pale yellowish gray, often tinged with purplish and crossed by two irregular brownish lines and marked with two black dots near the front margin. The moth deposits her eggs singly on the underside of the leaves. The eggs are flattened, irregularly oval, yellowish or greenish in color and about eV ii^f^li in length. They hatch in about a week. There are thought to be four generations a year. This beet webworm may be controlled by the measures sug- gested for the Hawaiian beet webworm. Reference U. S. Bur. Ent. Bull. 109, pp. 17-22. 1911. The Sugar-Beet Root-Louse Pemphigus helm Doane In the western United States from western Kansas and Nebraska to California, sugar-beets, beets and mangels often have the roots infested with a small, pale yellow plant-louse. In the case of sugar-beets, not only does the presence of the plant-lice greatly decrease the weight but also the sugar- content of the roots, in many localities making it unprofitable to grow the crop. This root-louse is a native of the western United States, where it is found most abundant on the roots of BEET AND Sl'INACII INSECTS 103 lamb's quarters but has also been reported as infesting the roots of the following plants : yarrow, knotweed, dock, aster, goldenrod, horse-weed, winged pigweed, foxtail, salt-grass, blue-joint grass, wheat, flax and alfalfa. The insect passes the winter in two forms, either as wingless viviparous females on the roots of its food plants or as eggs on the liark of two species of cottonwood {Populus angu.siifoUa and P. halsamifera) . The plant-lice that have survived the winter on the roots begin to give birth to living young in April or May, producing another generation of wingless viviparous females. Reproduction continues in this way until mid- summer, when winged forms begin to appear. Only about half of the lice acquire wings, the others continue breeding on the roots throughout the season. The form found on the roots is about \ inch in length, pale yellow in color and has the pos- terior part of the abdomen clothed with a white flocculent mass of waxy filaments. The remainder of the body is dusted with a white powder. Infested roots appear to be covered with a white or grayish mold. The winged forms produced on the roots are slightly larger than the wingless forms. The abdo- men is greenish, the thorax, head and antennae bluish black, lightly dusted with the whitish powder and there is only a little of the white flocculent material on the tip of the body. These winged forms begin to appear in midsummer and con- tinue until the end of the season but are most abundant in September and October. They migrate to the cottonwood, where, on the bark of the trunk, each female gives birth to four to seven young, part males and part females, the latter pre- dominating. These forms lack functional mouth-parts and do not take food. They molt four times in as many days and after mating the female deposits a single pale yellow egg in a crevice of the bark, which usually rests on a mass of bluish white waxy threads. The eggs hatch about the first of the following jNIay and the young plant-louse crawls out on the 104 MANUAL OF VEGETABLE-GARDEN INSECTS upper side of an opening leaf, where it establishes itself and begins feeding. A depression soon appears on the leaf at this point which gradually develops into a pocket-like outgrowth on the underside opening by a narrow slit in the upper side. Within this pocket-like gall, the plant-louse becomes mature and gives birth to seventy-five to one hundred and seventy- five young, all of which acquire wings and on escaping fly to beets or other food plants, where they produce young which descend to the roots. This migration from the cottonwood takes place mostly in July. Beets become infested both from lice living over in the ground on last year's crop or on weeds, and by the migrants from the cottonwood. The only practicable measure so far suggested for the con- trol of the sugar-beet root-louse can be employed only where irrigation is practiced. It consists in giving the plants the maximum quantity of water that they can stand, thus forcing the growth and at the same time producing conditions unfavor- able to the multiplication of the insects. Beets are also sometimes infested by another species of root- louse, Tychea brevicornis Hart. This peculiar plant-louse is wingless, with the abdomen very large and without cornicles. Corn, sorghum, salt-grass, pigweed, purslane, mustard, lettuce and dock have been recorded as hosts of T. brevicornis. A closely related species, determined as the European T. pha-scoli Passerini, has been reported as feeding on the roots of bean and clover. There is some doubt as to the determina- tion of the species of plant-lice found on the roots of many of our common weeds and vegetables. They are in great need of further study. References Wash. Agr. Exp. Sta. Bull. 42. 1900. Parker, Jour. Econ. Ent., 7, pp. 136-141. 1914. Parker, Jour. Agr. Research, 4, pp. 241-250. 191.5. • Maxson, Jour. Econ. Ent., 9, pp. 500-505. 1916. BEET AND SPINACH INSECTS 105 The Spinach Aphis Myzus 'persicce Sulzer The spinach aphis is also known as the green peach aphis, and as the common green-fl}^ of greenhouses. It is found in both Europe and America. In some locaHties it is the most serious insect enemy of spinach and is sometimes injurious to potato, tomato, eggplant, cabbage, turnip, radish, cauliflower, cucumber, kale, mustard, beet, rutabaga, water cress, pepper, horse-radish, celery, rhubarb, okra and lettuce. Eggplant often becomes infested in the hot-bed before transplanting. Radishes and rutabagas are sometimes attacked as soon as they come up, the first pair of leaves being entirely covered on the under- side by the lice. Such plants are badly stunted and sometimes killed. The spinach aphis also attacks a number of w^eeds, including pigweed, lamb's quarters, dock, shepherd's purse, dandelion, sow thistle, lupine and wild mustard. It is often found in greenhouses, where it infests the calla lily, carnation, rose, violet, oleander and many others. It has also been re- corded from tulip, pansy, hollyhock, tobacco, peppermint, rape and several ornamental plants. It is also sometimes found in the summer on apple, pear and lilac. The spinach aphis may pass the winter either in green- houses or on its food plants out of doors, where the winters are not too cold, or in the egg stage on the peach, plum, cherry, apricot, sand cherry and choke cherry. In the last case, the eggs hatch shortly before the buds burst in the spring and the stem-mothers are ready to begin reproduction when the blossoms appear. They are wingless and of a pinkish color. In the second generation the ])lant-lice are for the most part wingless, but instead t)f being pink, are pale yellowish green and usually marked with three indistinct darker stripes on the abdomen. In the third generation, most of the lice acquire wings. They 106 MANUAL OF VEGETABLE-GARDEN INSECTS are then greenish with the head, thorax and a large spot on the abdomen black. These winged forms leave the tree and fly to their various herbaceous food plants where they found colonies of young. When the lice have survived the winter on weeds or vegetables, reproduction is resumed as soon as new growth starts in the spring. They multiply rapidly and the plants soon become covered with the lice. The wingless forms found on the summer food plants have the bofly a uniform greenish yellow, without the darker lines found on the forms on the peach, or plum (Fig. 66). When the plant becomes Fig. 66. — Wingless viviparous crowded, winged forms (Fig. 67) are female spinach aphis (X 11). , i i • i • pi produced which migrate to new feed- ing grounds. The insects are most destructive to spinach late in the season when the cooler weather prevents the rapid multiplication of their predaceous and parasitic enemies, although they may become troublesome at any time. In the fall some of the winged females return to the peach, j^hmi ( r cherry, establish themselves along the veins on the un- derside of the lea^■es and give birth to true or ovipa- rous females. The latter are usually of a pinkish color, similar to the stem-mothers of the preceding spring. After pairing with the winged males, they deposit their eggs in the axils of the buds and in crevices of the bark. The eggs are small, oval and shining black, and closely resemble those of the common green apple aphis. Fig. 67. — Winged viviparous female spinach aphis (X 7^). BEET AND SPINACH INSECTS 107 Control. The spinach aphis is readily killed when hit by spraying with "Black Leaf 40" tobacco extract, 1 pint in 100 gallons of water to which 5 or 6 pounds of soap have been added. On spinach, however, and other plants the leaves of which lie close to the ground, it is not easy to obtain satisfactory control owing to the difficulty of wetting the underside of the leaves with the spray. References Taylor, Jour. Eeon. Ent., 1, pp. 83-91. 1908. Col. Agr. Exp. Sta. Bull. 133, pp. 32-37. 1908. Va. Truck E.xp. Sta. Bull. 2, i)p. 30-32. 1909. Other Beet and Spinach Insects Southern corn root-worm : 222 CaV)bage looper : 8 Cabbage webworm : 16 Garden webworm : 18 Harlequin cabbage bug : 38 Serpentine leaf-miner : 4() False ehinch-bug : 47 Yellow bear caterpillar : 3")7 Carrot beetle : 185 Celery leaf-tyer : 189 Celery looper : 191 Adelphocoris rapidus : 195 Western twelve-spotted cucumber beetle: 114 Belted cucumber beetle : 115 Melon aphis : 135 Garden springtail : 139 Potato aphis : 150 Common stalk-borer : 157 Grape colaspis : G7 Bean thrips : 69 Bean aphis : 76 Garden flea-hopper : 77 Spotted cutworm : 262 Greasy cutworm : 265 Red-backed cutworm : 267 Dark-sided cutworm : 268 108 MANUAL OF VEGETABLE-GARDEN INSECTS Striped cutworm : 270 Variegated cutworm : 276 Yellow-headed cutworm : 281 Spotted-legged cutworm : 282 Clover cutworm : 284 Army cutworm : 287 Army-worm : 288 Fall army-worm : 292 Beet army-worm : 294 Yellow-striped army-worm : 295 Striped blister-beetle : 302 Margined blister-beetle : 305 Ash-gray blister-beetle : 300 Black blister-beetle : 307 Nuttall's bhster-beetle : 308 Spotted blister-beetle : 309 Two-spotted blister-beetle : 309 Segmented black blister-beetle: 310 Large black blister-beetle: 311 Potato flea-beetle : 314 Eggplant flea-beetle : 320 Pale-striped flea-beetle : 321 Red-headed flea-beetle : 323 Smartweed flea-beetle : 323 Western cabbage flea-beetle : 327 Spinach flea-beetle : 329 Yellow-necked flea-beetle : 331 Three-spotted flea-beetle : 331 Larger striped flea-beetle : 332 Sweet potato flea-beetle : 332 Hop flea-beetle : 335 Root-knot nematode : 338 Sugar-beet nematode : 342 Millipedes: 342 CHAPTER V INSECTS INJURIOUS TO CUCUMBER, SQUASH AND MELON Cucurbits are subject to attack by a large number of insects, the most important of which are : the cucumber beetles, the squash bugs, the squash-vine borer, the pickle worm, the melon worm and the melon aphis. Cutworms and flea-beetles also occasionally cause serious loss. The watermelon is singu- larly free from insect enemies but is sometimes seriously in- fected by the melon aphis. The Striped Cucumber Beetle Diabrotica viltata Fabricius This small, yellow, black-striped beetle is one of the most serious enemies of the cucumber, squash, melon and related plants. It is a native of America and is to be found in this country wherever its food plants are grown except in the far West. The greatest injury is to the young plants soon after they come up, by the beetles that have just emerged from hibernation ; the larvae also burrow in the stem both above and below the ground and often feed on the underside of the fruit when it lies on the soil ; the beetles sometimes destroy the flowers by eating off the pistils and the new brood of beetles in late summer causes considerable injury to ripening fruit by gnawing holes in the rind. 109 110 MANUAL OF VEGETABLE-GARDEN INSECTS The beetles hibernate under trash or, when such protection is not available, in the ground below the frost line. They emerge from hibernation in the spring from April to June, the exact date depending on the locality and the season. They usually appear before cucurbit plants are up and feed for some time on the pollen of flowers and on the leaves of certain plants, apple, horse-chestnut, wild thorn, elm, syringa, juneberry and many others. The beetles, hungry after their long winter's fast, congregate on squash and cucumber plants just as they are coming up and feed on the tender leaves and gnaw holes in the stems often just at the sur- face of the ground. Many plants are killed outright while others are so injured that they make only a sickly growth. Okra is sometimes attacked. The beetle (Fig. 68) is from -j^ to ^ inch in length ; the head is black ; the thorax yellow and the wing- covers yellow with three longitudinal black stripes, the lateral pair not ex- tending to the tip. After feeding for some time, the beetles mate and the female begins egg-laying. Oviposition has been found to begin in Kentucky about the middle of June, on Long Island, New York, towards the last of June and in New Hampshire, about the first of July. Oviposition continues for about a month. Each female is capable of laying from seventy-five to one hundred eggs. The egg is about -^^ inch long, -^o^ inch wide, oval or elliptical in outline and light yellow in color. Some of the eggs are deposited in crevices in the ground but many are dropped by the female wherever she happens to be feeding. Eggs are sometimes found caught in the hairs of the leaves at the tip of the vines. The eggs hatch in a week or more and the Fig 68. — The striped cucum- ber beetle (X 5^). INJURIOUS TO CUCUMBER, SQUASH AND MELON HI \ar\x work their way down alone; the stem or under the vines or fruit where they lie on the <;round. They burrow into the tissue, eausing more injury in this stage than is usually thought. Squash vines have been observed praetieally killed in July and early August from the attaeks of the grubs. The stem just below the ground is completely riddled by their burrows. The larva becomes mature in about a month. It is then about ys inch in length and very slender ; the color is white with the head, thoracic and anal plates brown (Fig. 69). When mature, the larva constructs an earthen cell a few inches below the sur- face within which it soon transforms to a nearly white pupa. The pupal stage lasts a week or more. The beetles begin to emerge the last of August or in ^',^ ^, . , , , , , " . '^ Fig. G9. — Striped cucumber beetle, larva September m the more (X7^). northern part of the insect's range and after feeding for some time on f.owers, such as goldenrod and asters, go into hibernation with the occurrence of heavy frost. Late in the season the beetles sometimes injure melons by eating holes in the rind and have been know^n to eat holes in bean pods. In the North there is only one generation annually ; in the South it is thought that the insect is double-brooded. The beetles also serve as carriers for a serious disease of cucurbits known as bacterial wilt. They not only transmit the disease from plant to plant in the summer, but the hiber- nating beetles carry over the wilt bacteria and infect the plants in the spring. Control. As a rule, attempts to poison the beetles have not been suc- cessful l^ecause the insects refuse to eat leaves covered with the poison. In many cases it is practicable to protect the 112 MANUAL OF VEGETABLE-GARDEN INSECTS young plants by covering them with some kind of screen. Cheesecloth, mosquito-netting and wire screen are often used for this purpose. Various methods are followed to hold the covering in place over the plants ; sometimes a shallow wooden box is used, open at top and bottom and the screen is tacked over the top ; sometimes a barrel hoop is cut into halves, the two parts crossed at right angles and the ends stuck in the ground ; the screen is placed over the hoops and earth thrown on the edges to hold it down; sometimes the cover is made entirely of wire screen in the form of a cone and one grower successfully used wire pie-covers. The difficulty in using covers is that they have to be removed before the plants become very large and if the beetles are very abundant injury may follow. Much may be accomplished to prevent injury by keeping the plants thoroughly covered with bordeaux mixture or arse- nate of lead (paste), 3 pounds in 50 gallons of water. This renders the plants distasteful to the beetles and is especially valuable on cucumbers if used in connection with trap crops. Squashes are often more attractive to the beetles than cucum- bers and have been used successfully for trap crops. When it is desired to protect a field of cucumbers, a few rows of squashes should be placed around the field about a week before planting the cucumbers ; another planting of squashes should be made at the time the main field is set and if the beetles are abundant, more squashes should be planted about a week later. The beetles will collect on the squash plants, where it is sometimes possible to poison some when they first arrive and before they have had a chance to feed on unpoisoned foliage. Only a part of the trap crop should be sprayed or dusted with the poison for fear of driving the beetles to the cucumbers. Whenever a trap crop is used, it is important to keep the main crop well sprayed with bordeaux mixture or arsenate of lead. Experi- ments in New Hampshire have shown that arsenate of lead is just as effective as a deterrent for the beetles as bordeaux INJURIOUS TO CUCUMBER, SQUASH AND MELON 113 inixtiiiT and that it does not {'hock the growtli of the plants if appHed while they are small as does the latter. Tohaeeo dust, air-slaked lime and land plaster are of value as deterrents and will be found useful in the home garden. Much loss from beetle attack may be prevented by thorough cultivation and the use of the proper fertilizers to stimulate rapid growth. At the end of the season, all rubbish, including the old vines, should be collected and burned in order fo reduce to a minimum the shelter for the hibernating beetles. References N. Y. (Geneva) Agr. Exp. Sta. Bull. 158. 1899. Ky. Agr. Exp. Sta. Bull. 91, pp. 1-15. 1901. U. S. Bur. Ent. Cire. 31. 1898 and 1909. N. H. Agr. Exp. Sta. 19tli and 20tli Kept., pp. 499-513. 1908. Western Cucumber Beetle Diabrotica trivittata Mannerheim On the Pacific Coast the striped cucumber beetle is replaced by a closely related form. This species may be distinguished from its eastern relative by its darker color and by having the antennte and the greater part of the legs black. The habits and life history of the western form are very similar to those of the eastern species but it has not on the whole proved as injurious. There are said to be two generations annually. When attacking cucurbits, it may be controlled by the same means as suggested for that species. The Twelve-Spotted Cucumber Beetle Diabrotica duodecempunctata Olivier This beetle is also known as the southern corn root-worm and is discussed on page 222 as a corn pest. When attacking 114 MANUAL OF VEGETABLE-GARDEN INSECTS cucurbits, it may be controlled by the measures suggested for the striped cucumber beetle. The Western Twelve-Spotted Cucumber Beetle Diabrotica soror Leconte On the Pacific Coast the southern corn root-worm (page 222) is replaced by a closely related species which may be distin- guished by having the entire underside of the body and the legs black ; the antennae are only slightly paler at the base. The two posterior spots on the wing- covers have a tendency to coalesce (Fig. 70). The beetles attack cantaloupe, watermelon, squash and cucum- ber plants just as they are com- ing up and also eat holes in the fruit. They are also destructive to beet, spinach, bean, pea, cab- bage, turnip, potato, lettuce, mustard, peanut, corn, alfalfa and clover. They are especially troublesome on farms on which flowers are grown for seed. They sometimes defoliate young deciduous and citrus trees and cause considerable injury by eating holes in the fruit of the peach, prune and apricot. The beetles hibernate in sheltered places, emerging in early spring. After feeding for about eighteen to twenty-four days, the small, dirty white, oval eggs are deposited singly or in clusters of four or five to fifty in the ground near the base of the food plant, about one quarter to one half inch from the surface. The eggs are deposited over a period of about three weeks. They hatch in nine to twenty-six days with an aver- ao;e of about two weeks. The larvae have been found feeding Fig. 70. — The western twelve- spotted cucumber beetle ( X 5). INJURIOUS TO CUCUMBER, SQUASH AND MELON 115 on the roots of pea, alfalfa, peanut and beet and are said to mine into the stems and rinds of melons, cucumber and squash where they touch the ground. The larvfe become mature in five weeks to two months, those hatching first requiring the longer period. The full-grown grub is a little less than ^ inch in length, elongate, cylindrical, white or yellowish in color, with the head, thoracic shield and anal plate brown. The lar\'{e pupate in earthen cells in the ground and in about two weeks the beetles emerge. In Oregon the beetles of the new brood become abundant in early July ; in California somewhat earlier. The western twelve-spotted cucumber beetle can be con- trolled by the same measures as recommended for the striped cucumber beetle. The Belted Cucumber Beetle Diabrotica halteata Leeonte In the lower Rio Grande Valley in Texas truck cro})s are often subject to attack by the belted cucumber beetle. This beetle is about ^ inch in length, tTie head red and the prothorax and wing-covers bluish green, each of the latter marked with two spots in front, two transverse bands and a spot near the apex which are yel- lowish. The femora are greenish, the remainder of the legs blackish (Fig. 71). The beetles feed on pea, bean, potato, pepper, turnip, peanut, squash, cantaloupe, cucum- ber, watermelon, pumpkin, okra, spinach, beet, lettuce, onion, asparagus, corn, cotton, alfalfa, cowpea and other leguminous crops. They seriously injure Fig. 71. — The beltetl cucumber beetle (X 5|). 116 MANUAL OF VEGETABLE-GARDEN INSECTS eggplant, tomato and cucurbits by destroying the foliage and by feeding on the blossoms and blossom buds. The adults are active during the winter but do not lay eggs until March. The egg is oval, pale yellow in color and about 4V inch in length. The eggs are laid in the ground near the base of the food plant singly or in clusters of four or five. They hatch in nine to eleven days. The larvae have been found feeding on the roots of corn, sorghum and beans. The larva becomes mature in about twenty-five days. It is nearly ^ inch in length, light yellow in color with the head and anal plate brownish. The light yellow pupre, about ^ inch in length, are found in small earthen cells two or three inches below the surface. About eleven days are spent in the pupal stage. In the second generation the time required for the insect to pass through its different stages is somewhat shorter ; viz., egg stage five days, larval stage fourteen days and pupal stage five days. Experiments in Texas have shown that truck crops may be protected from the attacks of this beetle by spraying with arsenate of lead (paste), G to 10 pounds in 100 gallons of water or bordeaux mixture. Two other closely related cucumber beetles, Diabroiica con- nexa Leconte and Z). pidicornis Horn, occur in Texas and sometimes attack cucurbits and beans. The latter species deposits its eggs on the under surface of cucumber leaves. Reference U. S. Bur. Ent. Bull. 82, pp. 76-82. 1910. The Squash Bug Anasa trislis DeGeer Throughout the whole United States, cucurbits are subject to the attacks of a large brownish bug that has a highly offen- INJURIOUS TO CUCUMBER, SQUASH AND MELON 117 sive odor, licnce the name stink-})ug by which it is known in many loeahties. The insect ranges from Canada to Central America. Its favorite food phmts are squash and pumpkin, but melons and cucumbers are sometimes severely injured. As a rule the squash bug is more destructive in the small garden than in the fields of the commercial grower. The reason is that in the case of large tilled fields the quantity of hibernating shelter is relatively smaller, and as the insects are distributed over a larger area the injury is not so great to any particular ])lant. In the home garden the squash bug is a most troublesome and vexatious pest. The adult bugs hibernate in rubbish, in board-piles or under any convenient shelter. They emerge from winter quarters rather late in the spring and are often found about gardens resting under pieces of boards or other shelter, apparently waiting for the squashes to come up. The adult bug (Fig. 72) is about f inch in length and of a dirty brownish black color above and brown mottled wath black below. The old bugs attack the plants as soon as they are well out of the ground and often kill them outright. In feeding, the insect punctures the plant with the bristles of its beak and sucks out the sap. At the same time it apparently injects into the wound some injurious poison. When the plants are small, a few punctures are enough to cause serious injury. After mating, the female deposits her eggs in clusters of three or four to fifty or more usually on the under surface of the leaves. The arrangement of the eggs varies greatly ; usually they are placed in more or Fi( I. — The sciua.sh hug, adult (X 21). 118 MANUAL OF VEGETABLE-GARDEN INSECTS less regular rows, sometimes crowded closely together but more often rather widely separated. The egg (Fig. 73) is about YY inch in length and flattened on three sides ; the side next to the leaf is somewhat concave. When first laid it is whitish, but soon turns to a yellowish brown and gradually becomes darker as the time for hatching approaches. The eggs hatch in six to fifteen days. The young bug leaves the egg through an opening at one end made by pushing out a small circular disk-like piece of the shell. The newly hatched nymph is gayly colored ; the body is green, the legs, antennje and beak rose color and the head and the front part of the thorax another shade of rose. After a few hours the rose color changes to black. In the course of its development, the insect passes through five nymphal stages, molting its skin five times and Ficj. 73. — Eggs of the ''.'. .^ in^i i xe squash bug (X li). acqunung wmgs at the fifth molt. Alter the first molt, the color of the nymphs is a pruinose gray, almost white. Four or five weeks are passed in the nymphal stage. The young nymphs hatching from a cluster of eggs remain together for some time feeding on the underside of the leaf. After the first molt, they move about more freely. When not feeding, the older nymphs and the adults often congregate around the base of the plant or hide under lumps of earth. The feeding of the nymphs causes the injured leaves to wilt, curl up, turn brown and die. Sometimes the bugs kill the plant outright but more often they merely injure it so that growth is checked and the vine is unable to mature a full crop of fruit. The nymphs begin to reach maturity- in August but it often happens that frost kills the vines while many of the bugs are still immature. In such cases they often congregate on the unripe fruits, from which they are able to extract enough food to complete their growth. There is only one generation annually. I IXJURIOUS TO CUCUMBER, SQUASH AND MELON 119 Control. The adult squash bug is very resistant to contact sprays and recourse must be had to other methods of controh The number of bugs appearing on the plants in the spring can be greatly decreased by practicing clean farming and thus reduc- ing the available shelter for the hibernating insects. After the croj) is harvested, the vines should be raked up and either burned or converted into compost. This will prevent many of the later hatched nymphs from reaching maturity. The use of proper fertilizers and thorough cultivation will often enable the vines to withstand attack and outgrow the injury. After the ground has been fitted but before the plants are up, many of the bugs can be trapped under pieces of boards placed on the ground. They collect under such shelter during the night. The boards should be examined every morning and the insects killed by hand. It will also pay to keep watch of the plants for some time after they come up and hand-pick all the bugs found on them. All egg-masses should be destroyed by scraping them off with a knife or by crushing. When the nymphs are found, they too may be hand-picked or killed by spraying with "Black Leaf 40" tobacco extract, 1 part in 400 ])arts of water in which enough soap has been dissolved to make a good suds. An upturned nozzle will be found con- \'enient for reaching the young bugs on the underside of the leaves. References U. S. Div. Ent. Bull. 19, pp. 20-28. 1899. U. S. Div. Ent. Circ. 39. 1899 and 1908. N. H. Agr. Exp. Sta. Bull. 89. 1902. The Horned Squ.\sh Bug Anasa armigera Say The horned squash bug is frequently associated with the {)receding species, from Missouri to Maryland and southward. 120 MANUAL OF VEGETABLE-GARDEN INSECTS The two species are very similar in general appearance but the horned squash bug may be distinguished from the common form by the prominent angles of the thorax, by the row of four white spots on each side of the upper surface of the abdomen and by the spine near the tip of each femur. There is also an acute horn just in front of each eye (Fig. 74). The nymphs are easily distinguished. In the earlier stages A. armigera has the legs banded with red or brown and the next to the last seg- ment of the antennte is widened ; in .1. tristis the legs are nearly uniform black and the antennal segments are of nearly the same width ; in the later stages the sides of the thorax are strongly dentate in .1. armigera, smooth in .1. tristis. The life history and habits of the two species are nearly alike. The horned squash bug may be controlled by the same measures as are suggested for the common squash bug. In the South from Florida to Louisiana and New Mexico, another species, Anasa andrewsi Guerin-Meneville, closely related to the common squash bug, has recently been "reported as injurious to cucurbits. The adult of this species is more slender and of a lighter color than the common form but the insect does not differ greatly in life history, habits or the nature of the injury inflicted. The egg and early stages have not been described in detail. This subtropical squash bug may be controlled by the measures recommended for its northern relatives. 1 Fig. 71. — The horned squash bug ( X 2). Reference U. S. Div. Ent. Bull. 19, pp. 28-34. 1899. INJURIOUS TO CUCUMBER, SQUASH AND MELON 121 The Melon Leaf-Bug Pycnode es quadnmaculatus Guerin-Meneville This leaf-bug has been reported as seriously injuring melons, squashes and beans in Arizona. The adult bug is about ^ inch in length, black, mottled with gray and whitish. The legs are pale yellow with the outer two fifths of the hind femora black. The life history has not been recorded. The injury is caused by the feeding punctures of the insects. The adults are very active and difficult to hit with a spray. No satis- factory method of control has been devised. The Southern Leaf-Footed Plant-Bug Leptoglossus phyllopus Linnaeus In the southern states, tomato, eggplant, melon, potato and artichoke are often injured by the feeding punctures of a chocolate-brown bug closely related to the squash bug. This insect is also well known to fruit-growers from its habit of puncturing oranges, peaches, plums and pears, causing them to decay. The adult (Fig. 75) is between ^ and f inch in length. The hind tibiae are flattened and greatly expanded. The edge of the ex- panded portion is notched and toothed and flecked with yellowish white so as to resemble a bit of dried leaf are crossed near the middle by a yellowish white baud. The adults hibernate and in the si)riiig may be found in abundance on the yellow thistle, where they deposit their eggs end to end in a row along a stem or the midrib of a leaf. The egg is golden The wings Fig. 75. — The southern leaf-footed plant-bug (X H). 122 MANUAL OF V ECETABLE-dAllDEN INSECTS brown, cylindrical and flattened at each end and on the side of attachment. The eggs hatch in a few days and the young nymphs may be found sucking the juices from the plant. The nymphs are more reddish than the adults and do not acquire the leaf-like expansion on the hind legs until nearly mature. They become full-grown in about three weeks, pass- ing through five stages in the course of their development. Most of the injury to cultivated plants is inflicted by the adults, the nymphs being usually found only on yellow thistle. They puncture the stems of cucumber, melon and asparagus, causing them to wilt and die. The tender growing tips of tomato, potato, pea and bean are injured in a similar way and the bugs sometimes attack the fruit of tomato. In Louisiana the insect has been reported as a serious pest of the globe arti- choke. The bugs also puncture the bolls of cotton and are injurious to pepper. Control. In the small garden, hand-picking the bugs in the UK^rning while they are sluggish is probably the most practical method of controlling the pest. Since the insect breeds largely on the yellow thistle, this weed should not be allowed to grow in abundance in the vicinity of susceptible crops. In some cases it might be advisable to leave a few thistles as a trap crop on which the adults will congregate and where they may be destroyed. The Northern Leaf-Footed Plant-Bug Leptoglossus oppositus Say From New Jersey to Indiana, Missouri, Oklahoma and southward, squash, cucumber, melon and tomato are occa- sionally attacked by a leaf-footed plant-bug closely related to the species last treated. The northern form is slightly larger INJURIOUS TO CUCUMBER, SQUASH AND MELON 123 and stouter and the band across the front wings is represented by two small whitish spots. The wald food plants of the insect have not been accurately determined. The bugs often punc- ture the fruit of peach, plum, cherry, pear, tomato and cucum- ber and sometimes attack cotton bolls. They also feed on tlie stems of cucumber, squash, cantaloupe, watermelon and tomato, causing the vines to wilt and die. The insect hibernates in the adult stage but the bugs do not appear in the field until late in the season, about the first of July at Washington. The egg is bronze-brown, about yg inch in length, cylindrical and flattened at each end. The eggs are laid end to end in rod-like row's of six to twenty-six, attached to the stems or along the veins of the leaves. The eggs hatch in about a week and the young nymph leaves the egg-shell by forcing out a circular lid on the side near the end of the egg. The newly hatched nymph is coral-red in color with the legs nearly black. The basal half of the antennse is black and the outer half red. The insect passes through five nymphal stages and becomes adult in twenty-five days to about a month after hatching. There is only one generation annually so far as known. Control. The nymphs can be killed with "Black Leaf 40" tobacco extract, 1 part in 500 parts of water to which enough soap has been added to make a suds. Kerosene emulsion and strong soap solutions have also been suggested for the control of this pest. In the garden the adults may be hand-picked in the cool of the morning while they are sluggish. References U. S. Div. Ent. Bull. 33, pp. 18-25. 1902. Forbes, 23rd Kept. Stato Ent. III., pp. 197-108. 190.5. 124 MANUAL OF VEGETABLE-GARDEN INSECTS The Squash- Vine Borer Melittia satyriniformis Hiibner In many localities the squash-vine borer is the most injurious insect enemy of the squash and pumpkin. It also attacks cucumber and melon. It is most destructive to late squashes, such as Hubbard and INIarrowfat. The insect ranges from Canada, through the states east of the Rocky IVIountains south- ward into South America. The moths appear in the fields as early as April or May in Georgia and North Carolina, in early June in New Jersey and a little later in Connecticut, or at about the time that early cucurbits have come up. The moth has an expanse of 1 to 1-j inches ; the front wings are opaque, nearly black in color with metallic greenish reflections in certain lights ; the hind wings are transparent and scales are present only along the margin and on the veins. The abdomen is marked with red or orange ; the hind legs are long and ornamented with tufts of long orange, black and white hairs. The moths fly in the heat of the day and when on the wing are often mistaken for wasps. In the evening they may be seen resting on the leaves of the vines and are then easily caught. The female moth deposits her eggs on the stem of the vine near the base, while the plants are small and later at almost any point. The egg is about ^ inch in length, dull red in color, oval in outline, flattened on the side of attachment and has an impressed area on the upper side. The shell is very brittle. Each moth is capable of laying over two hundred eggs, but the average number is probably some- what less. The eggs hatch in six to fifteen days. The young caterpillar soon enters the vine and then burrows through the stem, preferably towards the root but often in the opposite direction. Later in the season the larvje may be found in all parts of the Stem and even in the leaf petioles and in the fruit. INJURIOUS TO CUCUMBER, SQUASH AND MELON 125 The young caterpillar differs from the later stages in having the head larger in proportion to the body, in being more hairy and in having the body more tapering behind. When full- grown, the caterpillar (Fig. 76) is about an inch in length ; the body is white and the head dark brown with an inverted V- shaped white mark. The burrows occupied by the larger larvre are usually wet, slimy and partly filled with excrement ; decay often ensues and hastens the death of the vine. The greater part of the excrement, however, is thrown out of the burrow Fig. 76. — The squash-vine borer (X Ij). through holes in the stem. These coarse, yellowish grains of frass collect on the ground under the vine and are usually the first indication that the plant is infested. The caterpillars reach maturity in about four weeks in the latitude of New Jersey. When mature the caterpillar leaves the stem, enters the ground one or two inches and there constructs a tough silken brownish or blackish cocoon into the outer layers of which particles of dirt are incorporated. The cocoon is about f inch in length. After making the cocoons, some of the cater- ])illars soon transform to puppe, while the others remain in the larval condition until the following spring. Those that pupate soon after spinning the cocoon usually transform to moths 126 MANUAL OF VEGETABLE-GARDEN INSECTS the same season. The dark brown pupa is about f inch in length ; its head is armed with a sharp horn-hke process by means of which it cuts its way out of the cocoon. After leav- ing the cocoon, the pupa works itself up to the surface of the ground in order to permit the escape of the moth. In the Gulf states the insect has normally two broods ; in the latitude of Washington the second brood is only partial while farther north, in New Jersey and on Long Island, the second brood is much smaller, and still farther north there is only one genera- tion annually. Control. The squash-vine borer cannot be controlled by applications of insecticides, but it may be held in check by practicing such of the following methods as are warranted by the severity of the outbreak or by other local conditions. As the insect passes the winter in the ground, it is not good policy to grow squashes in the same field year after year. If for any reason it is neces- sary to raise successive crops of squashes on the same ground, the land should be harrowed in the fall to expose the cocoons and then plowed deeply the following spring. In all cases the vines should be collected and destroyed as soon as the crop is harvested in order to prevent the late caterpillars from reaching maturity. If all the growers in a locality would co-operate in the early destruction of the vines, the number of moths appear- ing the following spring would be greatly reduced. In some cases much injury may be avoided by late planting in connection with heavy fertilization to promote rapid and heavy growth. In some localities the use of early squashes as a trap crop has been attended with success. A few early squashes, such as crooknecks, are planted early around the field and between the rows of the late varieties. The moths will deposit their eggs on the early squashes and the main crop, coming up later, will escape the greater part of the infestation. As soon as the INJURIOUS TO CUCUMBER, SQUASH AND MELON 127 early sciuushcs are harvested, or sooner if they erowd the main crop, the vines should be pulled up and burned or composted in order to kill the borers they contain. After the borer has once entered the vine, there is nothing to be done but to cut it out with a knife. If care is taken to make the cut lengthwise of the stem and if the vine is immediately covered with earth at the injured point, the wound soon heals and the vine con- tinues its growth. Some growers make a practice of covering the stem with earth two or three feet from the base in order t ) make the vine throw out a new root system, which will sustain the plant in case the main stem is injured at the ba,se. In s:)me cases it would i)ay t;) keep a sharp lookout for the moths in the evening when they are resting on the vines. They are easily seen and are not difficult to capture. For every female killed before she has deposited her eggs, there will be from one to two hundred less eggs laid on the vines. References N. J. Agr. Exp. Sta. Bull. 94, pp. 27-40. 1S93. U. S. Div. Ent. Bull. 19, pp. 34-40. 1899. U. S. Farm. Bull. G()8. 1915. The Pickle Worm Diaphania 'tiilidulis StoU The pickle worm and its near relative the melon worm are a serious drawback to the profitable growing of cantaloupes, squashes and cucumbers throughout the southern states. In some years the former appears in destructive numbers as far north as New York and Michigan and the moths have been taken in Canada. The insect ranges southward through the West Indies into South America. As far as known, its food plants are all members of the gourd family : cantaloupe, cucum- 128 MANUAL OF VEGETABLE-GARDEN INSECTS ber and squash. It has been reported as attacking the water- melon in Georgia ; the pumpkin is said to be immune. The pickle worm hibernates in the pu])al stage in a flimsy cocoon in a curled leaf of the food plant usually lying on the ground. The moths do not emerge until rather late ; the early part of June in Georgia and North Carolina. The moth (Fig. 77) has an expanse of 1 to ^ inches ; the general color of the wings is yellowish brown with a purplish metallic reflection in certain lights; a large irregular spot on the front wing and the basal two thirds of the hind wings are semi-transparent yellow. In both sexes the tip of the abdomen is ornamented with a brush of long scales, larger in the male. The moths do not fly during the day or in the early part of the night ; they are active and deposit their eggs after mid- night and go into hid- ing at daylight. The egg is about ^V inch in length, much flattened and elliptical in outline. It is nearly white when first laid but soon becomes yellowish. The eggs are deposited singly or in masses of three to eight on the flowers, flower-buds or on the tender opening leaves at the end of the ^'ines. They are loosely attached to the plant-hairs and can be easily brushed off. They hatch in three or four days and the young cater- pillars soon burrow into the tender tissue of the blossom or bud. The greater number do not reach the fruit until after the first or second molt. On squash many complete their growth within the blossoms, but on cantaloupes and cucum- bers the caterpillars that are feeding in the blossom buds usually Fig. 77. — The pickle worm moth ( X 2). INJURIOUS TO CUCUMBER, SQUASH AND MELON 129 migrate to the fruit when about half grown. Many of those that start feeding on the eluster of terminal buds burrow down into the stem and eomplete their growth there ; some are found in the leaf petioles. The vines are often riddled in this way but the greatest injury is caused by the burrows made in the fruit. On reaching the fruit, some of the caterpillars feed for- a time in the rind while others burrow directly to the center. While the caterpillar is near the surface, the excrement is thrown out of the opening ; later it is left in the burrow. The cater- pillars often leave one fruit and enter a second or third and may even migrate to another vine. In the case of cantaloupes and squashes, decay is almost certain to result whenever a caterpillar has gnawed through the rind, thus greatly increasing the loss. The newly hatched lar^'a is about Yt inch in length and yellowish white in color. After a shprt time a transverse row of brownish or blackish spots becomes apparent on each seg- ment. These spots become more distinct with successive molts and persist until the fourth, when they are lost. In the fifth and last stage the caterpillar is about finch in length, the head and thoracic shield are yellowish brown and the body is whitish, yellowish or greenish, depending on the nature of the food. Most of the caterpillars take on a dull coj)pery color above soon after the fourth molt. The caterpillar becomes mature in twehe to sixteen days after hatching. It then spins a loose silken cocoon, usually in a curled leaf, and after resting for about a day transforms into a pale green pupa, ^ to nearly f inch in length, which after a short time changes to brownish. The head of the pupa is bluntly pointed and the caudal end is acute and armed with a group of short hooked spines. In the summer the duration of the pupal stage is a week to ten days. The time required for the complete life cycle of the insect as determined in North Carolina \-aries from twenty-three to thirty-one days. In North Carolina there are four generations 130 MANUAL OF VEGETABLE-GARDEN INSECTS annually with sometimes a partial fifth when the fall is warm. The first generation is always small in numbers and is usually entirely overlooked. In the second and third generations the caterpillars become very numerous and the loss is correspond- ingly great. Cantaloupes harvested before the appearance of the second brood of caterpillars usually escape injury, while those that mature later are often entirely destroyed. Control. Attempts to control the pickle worm by spraying with arseni- cals have been unsuccessful. The caterpillars feed very little in the open and, therefore, do not eat enough of the poison to be killed. The number of moths appearing the following season can be considerably lessened by collecting and destroying the vines as soon as the crop is harvested. The waste fruits and fallen leaves should be raked up and destroyed with the ^'ines either by burning or by turning them into compost. Early fall plowing of infested fields will also destroy a large propor- tion of the larvse and pupae. Rotation of crops and planting cucurbits at a distance from fields infested the previous season does not give as much relief as would be expected, because the moths are able to fly a considerable distance in search of plants on which to deposit their eggs. By planting the crop early, much injury may be avoided and this method should be adopted whenever practicable. In the case of cantaloupes, excellent results in protecting the crop have been obtained by planting squashes as traps throughout the field. Squash vines with their large and odor- ous flowers are more attractive to the moths than other cucur- bits. If enough squash vines are present in a field, the moths will deposit nearly all of their eggs on them and" the canta- loupes will escape. For this purpose the squashes should be planted at intervals of about two weeks so as to furnish an abundance of buds and blossoms during July and August. INJURIOUS TO CUCUMBER, SQUASH AND MELON 131 The earlier squash vines should be removed and destroyed before many worms have reached maturity on them. The use of squashes as trap crops seems to be the most practicable way of preventing injury to cantaloupes in many parts of the South. References Ga. Agr. Exp. Sta. Bull. 54. 1901. N. C. Agr. Exp. Sta. Bull. 214, pp. 100-126. 1911. The IMelon Worm DiUphania hyalinata Linnaeus The melon worm is occasionally found as far north as New York, southern Canada and Michigan but causes little or no injury north of North Carolina. In the south- ern states, it is a serious pest of cantaloupe, squash, cucumber and pumpkin and has been known to injure water- melon. The insect passes the winter as pupae in loose silken cocoons in the dead leaves or under the shelter of any con^Tnient rubbish. The moths do not emerge vmtil rather late in the season, in June or July in North Carolina. The moth (Fig. 78) has an expanse of less than an inch to 1^ inches. The wings are pearly white with a broad shining, iridescent brown band along the front and outer margins. The head and front part of the thorax are brown. The body is silvery white and the tip of Fig. 78. — The melon worm moth ( X 2). 132 MANUAL OF VEGETABLE-GARDEN INSECTS the abdomen bears a conspicuous brush of elongate scales, yellowish at the base and white, brown or black at the tip. The eggs are laid on the buds, young leaves, stems and some- times on the main stalk of the vine, singly or in groups of two to six, sometimes overlapping. The egg is oval, about -^ inch in length, flattened and pearly white when first deposited but soon acquiring a yellowish tinge. The eggs hatch in three or four days in warm weather and the larvae begin feeding on the underside of the leaves or among the buds and sometimes bore into the latter. The newly hatched larva is about -^ inch in length, light straw-color with the head light brown. The two light stripes do not become apparent until after the first molt. In the second stage the color becomes yellowish or greenish from the ingested food. In the third stage the two white sub- dorsal stripes become more prominent and serve to distinguish the caterpillar from the pickle worm, in which they are not present. In the fifth and last stage the larva is f to l-j inches in length and mottled greenish yellow in color. Shortly before pupation, the larva contracts to about f inch in length and changes to a light yellow or straw-color, the white stripes hav- ing disappeared some days earlier. The caterpillars become mature in about two weeks and spin loose silken cocoons usually in a folded or rolled leaf in which they transform to brownish pupae about f inch in length. The moths emerge in a week or ten days. The life cycle requires a little less than a month in the summer in North Carolina. The first brood of caterpillars feeds to a considerable extent on the foliage and usually does not cause much injury to the fruit. The larvse of the later generations at first feed on the buds or foliage and do not attack the fruit until the third stage. On reaching the fruit, they may feed for some time on the surface but soon burrow through the rind causing decay. In North Carolina there are three genera- tions annually, the second, beginning the latter part of July, being the most destructive. INJURIOUS TO CUCUMBER, SQUASH AND MELON 133 Control Cantaloupes and cucumbers may be protected from the melon worm by using summer squashes for a trap crop as recom- mended for the pickle worm. As the young caterpillars feed to a considerable extent on the foliage and on the surface of the fruit, many of them may be killed by spraying with arsenate of lead (paste), 3 pounds in 50 gallons of water. Usually the arsenate of lead can be applied to the greatest advantage in combination with bordeaux mixture as used for the control of fungous diseases. As soon as the crop is harvested, the vines and waste fruits should be gathered up and destroyefl. Deep plowing and a rotation of crops will also tend to hold the in- sect in check. Reference N. C. Agr. Exp. Sta. Bull. 214, pp. 12G-143. 1911. The Sqt^\sii Ladybird Epihichiia horealis Fabricius Nearly all the ladybird beetles are })eneficial to man, feed- ing, both as larvic and adults, on plant-lice, scale-insects and other small insects or on the eggs of larger ones. The squash ladybird, however, is an exception to the rule; both beetles and lar\'a^ feed on the leaves of squash, pumpkin, cantaloupe, watermelon and cucumber. The insect is a native of America and ranges through the United States east of the Rockies and southward to Argentina. Besides the plants just mentioned, it feeds on the prickly cucumber or wild balsam apple and on the one-seeded bur-cucumber. While capable of causing seri- ous injury to cucurbits, the insect is rarely abundant enough to become of economic importance. The squash ladybird hibernates in the adult condition in sheltered places, often in large colonies. The beetles emerge 134 MANUAL OF VECET ABLE-GARDEN INSECTS about the middle of June in New Jersey. They are ^ inch in length, hemispherical in form and dull yellowish in color. The thorax has four small black spots and the wing-covers have twelve large spots arranged in three transverse rows (Fig. 79) . The yellow, elongate, subcylindrical eggs, xV ii^ch in length, are deposited in clusters of six to more than fifty. They hatch in about a week. The larva is yellow in color and armed with six rows of long branched spines ; when mature it meas- ures about f inch in length. The larvae feed generally on the underside of the leaves, eating off the surface in circular clearly defined areas. They become mature in about three weeks and then crawl to the upper surface of the leaf where they transform to pupse. The pupa is about ^ inch in length, yellow in color and covered with short simple black spines most abundant on the head, thorax and appendages. It is attached to the leaf by the posterior end of the ^'^iadybh^d^CxT'^'''' ^^^y- "^^^ P^P^^ ^^^^^ ^^^^^ ^^^^ ^^^ to nine days. The beetles appear from the latter part of July throughout the remainder of the season. There is only one generation annually. Control. The squash ladybird is usually present only in small num- bers ; in such cases hand-picking will be the easiest and cheapest method of control. When more abundant, it would be better to spray the vines with arsenate of lead (paste), 2 to 2^ pounds in 50 gallons of water. Reference U. S. Div. Ent. Bull. 19, pp. 11-20. 1899. INJURIOUS TO CUCUMBER, SQUASH AND MELON 135 The Melon Aphis Aphis gossypii Glover This insect is also known as the cucumber aphis, cantaloupe aphis, cotton aphis and orange aphis. When occurring in green- houses, it is known to gardeners as black aphis or black fly. It is widely distributed throughout the United States but has been reported as a serious enemy of cucurbits from Minnesota to Xew Jersey and southward. Its range extends to Brazil. It has attracted most attention in those localities where melons or cucumbers are grown on a large scale and in such cases the losses are often very great. It sometimes becomes of con- siderable importance as a cotton pest. The melon aphis has a wide range of wild food plants, including many common weeds and is occasionally found on a number of cultivated plants, such as spinach, okra, tomato, asparagus, eggplant, hop, morning-glory, bean and beet. The life history of the melon aphis has not been fully worked out and there is considerable difference of opinion as to how the insect passes the winter. It has been commonly supposed that winter eggs are produced in the fall and deposited on some food plant that will survive the winter. In fact eggs found on portulaca and strawberry have been described as belonging to this species. Great doubt has been cast on this view by the studies of Sanborn, who has shown that in Okla- homa the insect is unable to sur^•ive the winter in the open, and that each year it migrates northward from southern Texas, where it breeds continuously the year round. If it is true that the melon aphis does not winter over in the northern part of its range and that the infestation is annually renewed by migrants from the South, its habits in this respect are very similar to those of the famous green-bug of wheat, Toxoptera graminuin. 136 MANUAL OF VEGETABLE-GARDEN INSECTS The date at which the melon aphis makes its first appear- ance on cucurbits varies considerably from year to year, but in the northern part of its range it is usually rather late in the season. Winged females fly or are blown into the field and, alighting on a vine, crawl to the underside of a leaf and begin feeding on the juices of the plant, which are extracted by means of the insect's beak. The female begins to give birth to living young at the rate of four or five each day and is soon surrounded by a numerous colony of young lice. When about six days old, these in turn reach maturity and begin to produce young. After remaining on one leaf two or three days, the female may move to another and found a new colony. The feeding of the lice causes the leaves to curl downward, turn brown, shrivel and die. When food becomes scarce, many of the wingless lice crawl to the tender leaves towards the end of the vine ; these in time succumb to the attack and the vine is finally killed or stunted so that the crop is small and of inferior quality. A large proportion of the lice of each generation acquire wings while the others remain wingless. The former fly to other vines and start new colonies of aphids. In this way the whole field soon becomes infested and unless the aphids are checked by the attacks of their numerous insect enemies or killed by artificial means, the crop is sure to be destroyed. The wingless female is about 2V ii^ch in length, varying in color from yellow to green or black, the eyes are brown and the cornicles black. In the winged female (Fig. 80) the head and the greater part of the thorax are black with the abdomen varying from yellow to dark green. Breeding continues until frost. Males and egg- FiG. 80. — Winged viviparous female melon aphis ( X 10). INJURIOUS TO CUCUMBER, SQUASH AND MELON 137 producing females — the so-called true sexes — have not been observed. The melon aphis is held in check by the attacks of a large series of predaceous and parasitic insect enemies, most im- portant of which are several species of ladybird beetles, syrphus fly larvae, aphis lions and several species of parasites belonging to the family Braconidse. Under favorable weather conditions, these foes of the melon aphis are able to keep it so well under control that little or no damage is done. In cool, moist weather, however, following a backward spring, the activities of these beneficial insects are retarded and as the aphis is able to breed raj)idly under such conditions, the infestation becomes severe and it is not till late in the season that the enemies of the aphis r(>gain their supremacy. Many of these enemies feed on other kinds of aphids having difi'erent food plants and it has been suggested by Sanborn that it might be a useful practice to plant cabbage early around fields intended for cucurbits. The cabbage plants soon become infested with the cabbage aphis which furnish food for great numbers of predaceous and parasitic insects. At the first appearance of the melon aphis in the field, they will be on hand in sufficient abundance to hold the pest in check. Control. The melon aphis usually makes its appearance in a field on isolated vines scattered throughout the patch. It is important that a close watch should be kept in order to locate and destroy these first colonies. Growers sometimes pull up and bury the vines first attacked. Wliile the vines are small, it is possible to kill the aphids by fumigation with tobacco or carbon bisulfid. For this purpose portable covers are used made of oiled cloth stretched over a light wooden frame. The cover is placed over the vine and the tobacco fumes generated by l)urning strips of paper impregnated with nicotine. In case carbon 138 MANUAL OF VEGETABLE-GARDEN INSECTS bisulfid is used, the liquid is placed in a shallow dish under the cover and allowed to evaporate. About a teaspoonful is suffi- cient for one cubic foot of space. The cover should be made to fit tightly to the ground to prevent the escape of the gas. The fumigation method is of most value when only a small number of vines are to be treated and when the aphids make their appearance before the vines have begun to run so as to cover much space. In large fields, spraying is more practicable and more likely to give satisfactory results. For successful spray- ing it is necessary that the vines be trained to run in the rows ; this also makes the cultivation easier. When the vines are trained in this way, it is not difficult to kill nearly all the aphids by using "Black Leaf 40" tobacco extract, f pint in 100 gallons of water in which 5 or 6 pounds of soap have been dissolved. The spraying should be done as soon as the lice appear. A fine nozzle should be used, which, with good pres- sure, will produce a fine mist. It is important that the spray hit the underside of the leaves. This can be accomplished by using an upturned angle nozzle on a short extension rod. By doing careful and thorough work, it is possible to hit the under- side of practically every leaf. In case the infestation has be- come severe, it may sometimes be advisable to use a stronger solution of the tobacco extract, 1 pint of "Black Leaf 40" to 100 gallons of water. Much stronger mixtures will not injure the foliage but are unnecessary and rather expensive. This method of fighting the melon aphis has proved practicable under commercial conditions. References Pergande, Insect Life, VII, pp. 309-315. 1895. Tex. Agr. Exp. Sta. Bull. 89, pp. 43-46. 1906. U. S. Bur. Ent. Circ. 80. 1906. Okla. Agr. Exp. Sta. Bull. 98. 1912. 111. Agr. Exp. Sta. Bull. 174. 1914. INJURIOUS TO CUCUMBER, SQUASH AND MELON 139 The Squash Aphis Macrosiphum cucurbikr. Middleton Squash and pumpkin are sometimes found infested by a green plant-louse about yV i'l^'b in length. The body of the winged form is green with the thorax tinged with brownish and the abdomen has a median line of darker green. In the wing- less form the body is green with few markings. This species has been reported as injurious in Connecticut, Ohio and Illi- nois and as infesting eggplant in Florida. Fortunately, it does not, as a rule, become abundant on the vines until late in the season when the crop is nearly matured. Its wild food plants include shepherd's purse, wild mustard and ground ivy. The aphids multiply parthenogenetically throughout the summer, both winged and wingless females being present. Males and egg-laying females are produced only in the fall. The ovip- arous female is wingless with the body green. The antennte, except the first two joints, and the tip of the cornicles are black. The males are smaller than the females with the body black and the margin of the abdomen greenish. The antennae are black, dark brown at the base. The winter is passed in the egg stage. The squash aphis can be controlled by the measures sug- gested for the melon aphis. The Garden Springtail Sminthurus hortensis Fitch Many garden plants are subject to injury soon after they come up by a minute wingless insect that eats out very small holes in the epidermis of the leaves and enlarges the wounds made by other insects. The insect is about ^ inch in length, dark purple in color spotted with pale yellow. The head is 140 MANUAL OF VEGETABLE-GARDEN INSECTS large, separated by a narrow neck from the nearly globular united thorax and abdomen. At the tip of the latter there is a forked, tail-like appendage which when at rest is held close to the underside of the body and by means of which the insect is able to throw itself into the air. This habit has suggested the name of garden flea for these insects. The garden springtail has a wide range, having been reported from the northern United States, Europe, Japan and subant- arctic America. It has been reported as injurious in Maine, Massachusetts, New York, Indiana and Virginia. It attacks cucumber, squash, watermelon, cantaloupe, lettuce, bean, pea, cabbage, radish, turnip, kale, onion, beet, spinach, carrot, potato, tomato and tobacco and has also been found infesting wheat, rye and clover. The insects appear in great numbers just as the plants are coming up and so injure the leaves as either to stunt or kill the seedlings. The insects disappear in two or three weeks, practically all of the injury being done by the time the second or third true leaves appear. The life history of this springtail does not appear to have been worked out. Injury to seedlings by springtails may be prevented by dust- ing them with tobacco dust or air-slaked lime when they first come up and again in about a week if the insects are still present. The plants may be assisted to outgrow the injury by the appli- cation of a quick-acting fertilizer and by thorough early culti- vation. Reference Fitch, 8th Rept. State Ent. N. Y. for 1863, pp. 186-191 in 7th to 9th Repts. 1865. Other Cucumber, Squash and Melon Insects Corn ear-worm : 211 Southern corn root-worm : 222 Western corn root-worm : 225 Stink-bugs: 232 Garden webworm : 18 INJURIOUS TO CUCUMBER, HQUASH AND MELON 141 Serpentine leaf-miner : 46 Yellow bear caterpillar : 357 Tarnished plant-bug : 192 Sugar-beet webworm : 97 Spinach aphis : 105 Grape colaspis : 67 Garden flea-hopper : 77 Well-marked cutworm : 263 Greasy cutworm : 265 Striped cutworm : 270 Dingy cutworm : 271 Variegated cutworm : 276 Spotted-legged cutworm : 282 Army-worm : 288 F^all army-worm : 292 Yellow-striped army-worm : 295 Striped blister-beetle : 302 Margined blister-beetle : 305 Potato flea-beetle : 314 Tobacco flea-beetle : 319 Pale-striped flea-beetle : 321 Larger striped flea-beetle : 332 Hop flea-beetle : 335 Root-knot nematode : 338 Millipedes: 342 Wheat wireworm : 348 Red-spider : 351 Corn and cotton wireworm : 349 CHAPTER VI POTATO INSECTS The potato plant is a native of America and the insects affecting it are, with few exceptions, indigenous to the New World. In the East the most important potato insects are the Colorado potato beetle and the potato flea-beetle. The latter is treated on page 314. In California the potato tuber moth has in some localities threatened the potato-growing industry. Potatoes are especially subject to attack by blister- beetles. These pests are discussed in Chapter XVI. The Colorado Potato Beetle Leptinotarsa decemlineata Say The genus to which the Colorado potato beetle belongs occurs in greatest abundance in southern Mexico and Central America and it is supposed that this species originated in that region where it is now represented by closely related forms. It had, however, migrated northward so that by the early part of the last century it occupied a strip on the eastern slope of the Rocky INIountains from Texas and New Mexico north- ward to the Canadian boundary. The potato beetle was first described by Thomas Say in 1824 from specimens collected in the upper Missouri River Valley. The original food plant of the insect was the buffalo bur, Solarium rostratum. When the early settlers first began to plant potatoes in western 142 POTATO INSECTS 143 Nebraska, the beetles discovered in this new plant a food greatly to their liking. In 1859 the beetles were feeding on potato about one hundred miles west of Omaha in Nebraska. This marks the beginning of the rapid and destructive eastern spread of the species. The Missouri River was crossed about 1861 and the Mississippi by 1864. The main line of advance continued around the south shore of Lake Michigan, across Illinois, Indiana and Ohio, down through the natural highway of the lower Great Lakes through Ontario to the Province of Quebec and through Pennsylvania and New York and into New England. The Atlantic Coast was reached in 1874. In the early part of this great migration, the beetles averaged less than fifty miles a year, but after crossing the Mississippi River the yearly advance was considerably greater and the whole distance was covered at an average rate of about eighty- eight miles a year. It is now difficult to realize the apprehension with which the farmers viewed the coming of the potato beetle. Spray- ing was then unknown and arsenical poisons had not yet been used for the control of injurious insects. Although the value of paris green for the destruction of this pest was demonstrated in 1869, suitable apparatus for its application was not to be obtained. The first dusting and spraying machines were crude, clumsy and generally inefficient. If one considers the enormous hordes in which the beetles appeared and the com- pleteness with which they defoliated the plants in the newly infested areas, some idea can be gained of the serious situation that confronted the potato-growers of this period. In the newly occupied territory the beetles found few of their natural enemies and, therefore, for a time multiplied unchecked. In their eastward advance they moved through a region which was thickly settled, where their food was grown in great abundance and in a climate to which they easily adapted themselves. They were aided in their rapid advance 144 MANUAL OF VEGETABLE-GARDEN INSECTS by the prevailing west and southwest winds during the season when the beetles were on the wing. The rapid spread of the Colorado potato beetle across the eastern United States has had no equal in historic times, except possibly in the case of Fig. 81. — Eggplant killed by the Colorado potato beetle. the recent advance of the cotton boll-weevil through the cotton belt of the southern states. After reaching the Atlantic Coast in 1874, the potato beetle gradually extended its range southward east of the Appa- lachian Mountains, but northern Florida was not invaded until about 1900. The advance down the Mississippi Valley POTATO INSECTS 145 had also been slow and the beetles did not appear in central Louisiana until al)out the same date. The potato beetle is now generally distributed east of the Rocky Mountains from Montana to New Brunswick and Nova Scotia and southward to northern Florida. It also occurs in New ^Mexico and Ari- zona and in Idaho, Washington and Alberta. Where the potato is not available for food, the beetles will sometimes attack eggplant (Fig. 81), tomato, pepper and even tobacco. Ground cherry, thorn apple, henbane, Jamestown weed, horse nettle, belladonna and petunia also serve to carry the beetles through periods of scarcity. The potato beetle hibernates as an adult sometimes under rubbish but more frequently in the soil at a depth of several inches. The beetles emerge from their winter quarters in the spring just before early planted potatoes come up. At this time they will feed on ])ieces of seed potatoes left on the surface and will some- times dig into the soil in search of the tender sprouts. Fig. 82. — The Colorado potato beetle, r,^, PIP , • 1 Pfigs and newly hatched larvae iney teed tor a tune on the (enlarged). tender foliage and then, after pairing, deposit their eggs on end in masses on the under- side of the leaves (Fig. 82). Each mass contains from four or five to nearly seventy eggs with an average of about twenty- five. The egg is about ^ inch in length, elongate oval and orange in color, with the surface smooth and shining. The egg is glued to the leaf with a small mass of orange-colored material. The female is capable of laying from 200 to over 1800 eggs with a probable average of 400 or 500. The eggs do not ripen continuously but in successive batches; all the eggs which ripen at a given time may be deposited in one or L 146 MANUAL OF VEGETABLE-GARDEN INSECTS iiKire clusters. The average length of the egg-laying period in the field is probably between four and six weeks, but under cage conditions the beetles have continued to lay eggs for ten weeks or more. The eggs hatch in four to nine days. On h a t c h i n g, the young larva be- gins at once to feed on the leaves. In the first stage it is about yo i'lch in length, dark red in color with the head, thoracic shield and legs black and with a double row of black spots along each side of the body. In the course of its development the larva passes through three or four stages according to different observers. In the last stage it is about f inch in length ; the head, legs and posterior part of the cervi- cal shield are black; the body is red, lighter than in the first stage and there are two rows of distinct black spots on each side ; the ab- domen is strongly convex and is much larger than the head and thorax (Fig. 83). The larvse be- come full-grown in ten days to three weeks and then enter the ground to a depth of several inches where they transform Fig. 83. — Larvs of the Colorado potato beetle ( X f). Fig. !S4. — Pupa ot the C'olo- rado potato beetle ( X 4). POTATO INSECTS 147 in earthen cells to pupje. The pupa is a little over ^ inch in length and orange-yellow in color (Fig. 84). After a pupal period of five to ten days the adults emerge. The beetle is about f inch in length, strongly convex above and yellow in color. The head has a triangular black spot between the eyes ; the prothorax is marked with two divergent elongate black spots near the middle and four to six smaller spots on each side. Each wing-cover has the sutural margin and five narrow stripes black, the second and third united at the tip ; the knees and tarsi are blackish (Fig. 85). The beetles are often called hard-shells to distinguish them from the larvae, which are known as slugs or soft-shells. After feeding a few days, the beetles may either go into the ground for a more or less extended period of aestivation or they may immediately lay eggs for a second generation. Owing to the long period over which egg-laying takes place, all stages of the insect may be found at any time during the latter part of the summer. There are normally two generations pro- duced annually but in some cases a small third brood of larvae may develop and in JNIontana it is claimed that there is only one generation. Fig. 85. — The Colorado potato beetle (X 25). Control. For many years paris green has been the standard insecti- cide for the control of the Colorado potato beetle. It is some- times applied in the form of a dust, 1 pound in 50 pounds of land plaster or hydrated lime. It is more effective, however, when applied in water, 1 pound in 50 gallons. To avoid burn- ing the foliage, 2 pounds of lime should be added. Paris green is most effective and least liable to injure the vines when ap- plied with bordeaux mixture as used for the control of fungous 148 MANUAL OF VEGETABLE-GARDEN INSECTS diseases. From 8 ounces to 1 pound should be added to each 50 gallons, depending on the thoroughness of the application. Arsenate of lead, 3 or 4 pounds of the paste to 50 gallons, has also been found satisfactory. It adheres to the foliage better than paris green but does not kill the insects so quickly. It may be used either in water or in bordeaux mixture. Arsenate of lead may also be applied in the dry or powdered form diluted with sulfur, gypsum or hydrated lime. Experiments in New Jersey, however, have shown that, on the whole, this treatment does not give as good results in yield as are obtained by spray- ing with bordeaux and arsenate of lead. When expense is an important item, sodium arsenite may be used instead of paris green or arsenate of lead with satisfactory results, at the rate of 1 quart of the stock solution to 50 gallons of bordeaux mix- ture. For the preparation of sodium arsenite see page 369. The first application for the potato beetle should be made about the time the eggs are hatching. The larvse are much harder to kill when nearly full-grown and they have then caused the greater part of the damage. It sometimes happens that the eggs are deposited in patches in the field so that the infestation is not general. In such cases it is a good plan to treat these areas early and not wait till the whole field can be sprayed. In Virginia, where potatoes are seriously injured by the over-wintered beetles, just as the plants are peeping through the ground, it is recommended that they be dusted with a mixture consisting of 1 pound of paris green and 20 to 30 pounds of hydrated lime. This application is intended to protect the plants until they are large enough to be sprayed. In the home garden where only a few potatoes are grown, it is practicable to hand-pick the beetles into pans containing a little kerosene oil or the plants may be dusted with paris green or powdered arsenate of lead diluted with land plaster, hydrated lime or some similar substance. For the protection of tomato plants, arsenate of lead should POTATO INSECTS 149 be used instead of paris green because of the danger of foliage injury by the hitter. References Riley, Potato pests, N. Y. 1876. Tower, An investigation of evolution in Chrysomelid beetles of the genus Leptinotarsa. Washington. 190(5. U. S. Bur. Ent. Cire. 87. 1907. Girault and Rosenfeld, Psyche, 14, pp. 4'>-~u. 1907. Girault, Ann. Ent. 8oe. Am., 1, pp. 155-178. 1908. U. S. Bur. Ent. Bull. 82, pp. 1-8. 1909. Girault and Zetek, Ann. Ent. Soc. Am., 4, pp. 71-83. 1911. Va. Truck Exp. Sta. Bull. 14. 1915. Johnson and Ballinger, Jour. Agr. Research, 5, pp. 917-925. 1916. The Three-Lined Potato Beetle Lema trilineata 01i\'ier Throughout the United States and Canada east of the Rocky IMountains, potatoes and tomatoes are sometimes attacked by the larvie of a ycHowish leaf- beetle (Fig. 86) about \ inch in length. The head and thorax are reddish yellow, the latter constricted at the middle and usually marketl with two black spots. The wing- covers are reddish yellow and marked with three black stripes. The an- tennae are black, except the base, and the legs are reddish yellow with the outer half of the tibia? and tarsi black. A closely related species, Lema nigrocittata Guerin- Meneville, occurs in California ; by some it is considered identical with the eastern species. The three-lined potato beetle probably hibernates in the adult condition, the beetles appearing in early spring. They Fig. SG. — The three-lined potato beetle (X 3^). 150 MANUAL OF VEGETABLE-GARDEN INSECTS feed at first on various wild plants, preferring solanaceous weeds. As soon as potato and tomato plants are available, the beetles migrate to them and deposit their eggs usually on the underside of the leaves in clusters of six to ten. Each egg is about -j^ inch in length, smooth, oval and yellowish in color. The eggs hatch in about two weeks and the young larvae at first feed in a row side by side, beginning at the edge of the leaf and moving backward as they devour the tissue. When mature the larva is about ^ inch in length with the head, thoracic shield and legs black and the body yellowish. The body of the larva is kept moist and sticky by a secretion and is usually covered with a coating of excrement. The grubs become full-grown in about two weeks and then enter the ground where they construct earthen cells lined with a gelatinous secretion from the mouth. The pupal period occupies about two weeks. There are said to be two generations annually. The three-lined potato beetle has never been reported as a very important pest but it may occasionally become trouble- some when conditions are favorable for its development. It may be controlled by spraying m- ith arsenical poisons as recom- mended for the Colorado potato beetle. References Harris, Insects injuriotis to vegetation, pp. 9.5-9G. 1841. Fitch, 10th Rept. N. Y. State Ent., N. Y. State Agr. Soc, 24, pp. 441- 447. 1864. The Potato Aphis Macrosiphum solanifolii Ashmead Although the potato aphis is generally distributed through- out the United States and southern Canada, injurious out- breaks have been reported only from ]\Iaine, Connecticut, New York, New Jersey, Pennsylvania, Ohio, Illinois, Iowa, Kentucky, Maryland and Virginia and the provinces of Ontario, POTATO INSECTS 151 Quebec and Prince Edward Island. \Yhile the insect is doubt- less present in small numbers each year in these states, it has appeared in destructive abundance only at intervals of several years. This plant-louse is not confined to potatoes but also injures tomato, eggplant, pea, turnip, beet, spinach, pepper, asparagus, sunflower and sweet potato and has been found infesting various weeds such as ground cherry, Jamestown weed, ragweed, lamb's quarters and wild lettuce. It is also found on canna, hollyhock, gladiolus, iris and matrimony vine. It was originally described from specimens collected on the pepper-vine, Solanum jasminoides, in Florida. The potato aphis passes the winter in the form of shining brownish black eggs on the rose and possibly on other peren- nials. The eggs hatch about the time the leaf-buds are opening and the young aphids reach maturity on this plant. Probably in the second or third generation, most of the aphids migrate to the potato and other herbaceous food plants. Throughout the entire growing season, only female aphids are produced and these give birth to living young. Both winged and wing- less females occur through- out the season. In warm weather a female reaches maturity in ten days to two weeks and may gi\e birth to more than fifty young over a period of about fourteen days. The adult winged viviparous „ , . 1 i 1 • 1 Fig. 87. — The winged viviparous female female is about i mch, potato aphis (x 5). and the wingless form about ^ inch in length (Figs. 87 and 88). Both forms are usually green but pink individuals are common. The potato aphis closely resemliles the pea aphis but may be dis- tinguished under the microscope by having the tip of the 152 MANUAL OF VEGETABLE-GARDEN INSECTS cornicles reticulate for a short distance instead of being im- bricated throughout. At the approach of cold weather, the winged forms migrate to the rose and there produce a generation of winged males and wingless egg-laying females. In Maine the winter eggs are laid in late September. Fig. 88. — The wingless viviparous female potato aphis ( X 7i) The time at which the pest becomes destructive to potatoes varies from year to year. In Maine it has been found most abundant in August, but in 1917, when the outbreak was the most extensive and destructive so far recorded, the attack be- came serious in New York in early July and in Ohio in late June. On potatoes the aphids cluster on the underside of the leaves, causing them to curl downward. They also infest the tender tips and the blossom stems. When badly infested, the vines soon become covered with the sticky honey dew secreted by the aphids. The tips are first killed, and in 1917 many large fields were observed in which all the plants were killed to the ground. Even when the vines are only partly killed, the size and qualit}^ of the crop is seriously affected. On tomatoes the lice also infest the leaves but cause their greatest injury by attacking the blossom stems and young POTATO INSECTS 153 fruits. The blossoms arc killed, the fruit is dwarfed and the ripening period is delayed so that in many eases the crop is a total loss. Control. The potato aphis can be killed by spraying with "Black Leaf 40" tobacco extract, ^ pint in 50 gallons of bordeaux mixture. If for any reason bordeaux mixture is not used, the "Black Leaf 40" may be diluted with water at the same rate but in this case 3 or 4 pounds of soap should be added to each 50 gallons. Since many of the aphids are on the underside of the leaves, it is necessary to have the spray directed upward. Some potato-sprayers have the nozzles arranged to do this. Other potato-sprayers may be adapted for this work by remov- ing the nozzles and inserting a l-foot extension directed down- ward. On the end of this extension a T-coupling is attached. To each side of the T-coupling is joined a piece of pipe 6 inches in length directed at right angles to the rows and equipped with a 45° angle nozzle, so attached as to throw the spray obliquely upward and backward. This outfit can be used to advantage as long as the plants are upright. After the vines are down, effecti\e work can be done by using two leads of hose 10 or 12 feet in length equipped with 4-foot extension rods and angle nozzles. With this outfit a traction pump will not deliver the liquid in sufficient quantity and it is, therefore, necessary either to operate the pump by hand or with a gaso- line engine. It requires at least 100 gallons of the spray mate- rial to the acre to be effective. It is usually better to use the tobacco extract in combination with the bordeaux mixture than with water and soap because of the value of the bordeaux in pre\enting potato blight. Furthermore, it has been ob- served that potatoes regularly sprayed with ])()rdeaux mixture are less likely to be seriously infested with the a})hid than un- treated vines. Where there is any reason to fear an outbreak 154 MANUAL OF VEGETABLE-GARDEN INSECTS of the potato aphis, careful watch should be kept of the plants and when the lice begin to appear in any abundance, steps should be taken to destroy them before the vines become stunted. The potato aphis is often aided in its destructive work on potato and other garden plants by the spinach aphis, for a discussion of which see page 105. References Maine Agr. Exp. Sta. Biill. 147. 1907. Maine Agr. Exp. Sta. Bull. 190. 1911. Maine Agr. Exp. Sta. Bull. 242. 1915. Ohio Agr. Exp. Sta. Bull. 317. 1917. The Apple Leafiioppek Empoasca viali Le Baron The well-known apple leafhopper, a troublesome pest on apple nursery stock, often breeds during the summer on potato vines. The insect passes the winter in the egg stage on the apple and the first brood of nymphs develops on this plant, reaching maturity about a month after hatching. Some of the adults of the second and later broods migrate to potato and there insert their small, whitish, elongate, slightly curved eggs about ^o i'lch in length, in the tender parts of the potato vines. The eggs hatch in a few days and the young nv'mphs, in company with the adults already present on the vines, feed on the underside of the leaves, causing them to curl and stunt- ing the tender growing tips. The injury is most noticeable in periods of drought. The young hoppers pass through five nymphal stages, acquiring wings at the fifth molt. The nymphs are pale greenish and in the last stage are about yV inch in length. The adult leafhoppers are about ^ incli long and of a pale yellowish green color, with six or eight distinguishing white spots on the front margin of the pronotum (Fig. 89). POTATO INSECTS 155 When disturbed the nymphs run in all directions but the adults can jump quickly and fly away, often rising in swarms as one walks through an infested field. About a month is required for the completion of the life cycle. There are three generations of the insect a season on the potato. In the fall the adults find their way back to the apple and there deposit the winter eggs in the bark of the smaller branches, just below the epidermis, two-year-old wood being most often selected. The position of the egg is indicated by a low blister-like ele^'ation of the bark about 3^ inch in length and about half as wide. The apple leafhopper has also been reported as causing spots on the white stalks of celery and as feeding on sugar- beets and beans. It is rarely of sufficient importance on potato to warrant special applications of insecticides. The nymphs may be killed by spraying with "Black Leaf 40" tobacco extract as recommended for the control of the potato aphis. Fig. 89. — The i.pple leafhopper, adult (X 11;. References Minn. Agr. Exp. Sta. Bull. 112, pp. 145-164. 1908. Iowa Agr. E.xp. Sta. Bull. 111. 1910. Iowa Agr. Exp. Sta. Bull. 1.5.^), pp. 394-400. 1915. The Potato Stalk-Weevil Trichohnris trinotala Say Throughout the northern states from New York to North Carolina westward to Kansas, Nebraska, Texas and southern California, potatoes are subject to the attacks of a small weevil, the larva of which bores in the stalk. This insect has been found most injurious in Kansas, Nebraska and Iowa, but more 156 MANUAL OF VEGETABLE-GARDEN INSECTS or less serious outbreaks haAe occurred in southeastern Penn- sylvania and in New Jersey. In New York the insect has been troublesome in the upper Hudson River Valley and in Ontario on Pelee Island in Lake Erie. Its wild food plants include a number of solanaceous weeds, such as ground cherry, James- town weed, buffalo bur and horse nettle and it has also been recorded as infesting cocklebur. p]ggplant is sometimes at- tacked and there is at least one record of injury to tomato. Early potatoes are more subject to injury than late varieties. The adult (Fig. 90) is a snout-beetle, about ^ inch in length, bluish gray in color with the head and scutellum black and with a black spot on each side near the margin at the junction of the prothorax and the base of the wing-covers. The ground color of the beetle is black, its blue-gray color being derived from a thick covering of narrow scales. The beetles appear in the field in spring and feed for a time on the stems of the potato which they puncture with their beaks. The female inserts her eggs singly in the stalk or branches and sometimes even in the leaf petioles. In ovipositing, she first hollows out a cavity with her beak and then turning around places the egg in the puncture. The egg is oval, yellowish white and about ^V inch in length. The eggs hatch in a week to eleven days and the young grub burrows down through the pith several inches and then turning about retraces its course. When nearly full-grown, it eats out the entire pith for some distance. When mature the larva is | to :^ inch in length, yellowish white, with the head brownish. Legs are lacking. The presence of the grubs is indicated by a wilting and dying of the leaves, while the stem may remain green for some time. Several Fig. 90. ~ The potato .stalk-wccvil ( X 6|). i POTATO INSECTS 157 larvse may infest the same stalk and often kill the entire plant. When full-grown, the grub eats out an exit hole for the future beetle nearly to the surface but does not penetrate the outer bark. It then constructs a cell or cocoon of fibers stripped from the wall of the burrow and then transforms into a creamy white pupa about ^ inch in length. In Kansas the larvae begin to pupate about the middle of July and in New Jersey the last of the month but some do not reach maturity till early fall and in a few cases have been known to enter the winter in this stage. The insect spends from eight to fifteen days or longer in the pupal stage. Although some of the beetles are to be found in the stalks in early August, they do not usually emerge until the following spring, but when the stalks are broken open they may be forced to seek winter quarters elsewhere. There is only one generation annually. Control. The potato stalk-weevil is best held in check by collecting and burning the vines soon after the crop is dug. If this is practiced regularly and if all solanaceous weeds in which the weevils breed are reduced to a minimum by clean farming, the pest can be prevented from doing any serious damage. References N. J. Agr. Exp. Sta. Bull. 109, pp. 25-32. 1895. Kans. Agr. Exp. Sta. Bull. 82. 1899. U. S. Div. Ent. Bull. 33, pp. 9-18. 1902. The Com.mon Stalk-Borer Pnpnipemn nitela Guenee The common stalk-borer is generally distributed throughout the United States, and Canada east of the Rocky Mountains. Although the insect is usually present in small numbers, oc- casionally serious outbreaks occur locally. The borers attack 158 MANUAL OF VEGETABLE-GARDEN INSECTS potato, tomato, eggplant, pepper, corn, bean, rhubarb, spinach, cauhflower, dahlia, aster, chrysanthemum, lily, hollyhock, golden glow, peony, sunflower, castor bean and several other ornamental plants. Their wild food plants include ragweed, great ragweed, cocklebur, burdock and pigweed. Wheat, rye, barley, blue-grass and timothy are sometimes attacked as well as the tender shoots of raspberry, blackberry, currant and gooseberry. The insect passes the winter in the egg stage on the stalks of such plants as ragweed, dock, pigweed and burdock. The egg is -^ inch in diameter, brownish gray, globular, slightly flattened and with numerous ridges radiating from the tip. The eggs hatch in late May or early June and the young cater- pillar begins feeding on the first suitable plant that it finds. It may first feed as a miner in the leaves for a few days and then burrow into the stem. Ragweed, pigweed, blue-grass and timothy, as well as wheat and other grains, are often attacked by the young larvje. Many of these plants are soon killed and the caterpillars then migrate to other plants. It usually hap- pens that the young larvae get their start in the rank weeds surrounding the field or garden and when forced to migrate in search of fresh food attack the cultivated crops. It has often been noticed that corn is most subject to infestation along the edge of the field and that other crops, such as potatoes and tomatoes, are more liable to injury when grown in small gardens than when planted in large open fields. In New York the cat- erpillars usually attract most attention by their injuries to garden plants from the middle of June to the last of July. The caterpillar until the next to the last molt is dull brown, the head, cervical and anal shields honey-yellow% smooth and shining, with a black stripe on each side of the head and on each side of the cervical and anal shields. Each end of the body is grayish brown with a white dorsal stripe and two white stripes on each side. The integument is apparently thinner from the POTATO INSECTS 159 Fig. 91. — The common stalk-boFvT, larva (X U). middle of tlie tliird thoracic segment to tlie middle of the fourth abdominal segment, dirty greenish gray with the white dorsal stripe only present, the lateral stripes being broadly interrupted. This caterpillar is distinguished from its near relatives by having but one tubercle behind the spiracle on the eighth abdominal segment ; by lacking the large plates on the second and third thoracic segments and by the presence of a pair of small plates on the next to the last abdominal segment. The full-grown caterpillar is slightly less than 1^ inches in length and similar to the preceding stages except that the stripes on the body gradually fade out into a dirty greenish gray and finally disappear shortly before pupation occurs (Fig. 91). The caterpillars reach maturity in August and transform, usually in the burrow, into a brownish pupa f inch in length. The moths emerge in September and October and deposit their eggs on the stalks of their food plants. The pupal period lasts about three weeks. There are two varieties of the moth. In the typical form (P. nifrlo), the front wings are grayish brown with a slight olive tinge, lightly dusted with white. The usual outer line is pale and bent inw^ard about one fourth of the distance from the front margin of the wing and then runs nearly straight across the inner margin. The hind wings are slightly paler in color except towards the margin and on the veins. In the ft^ 1^ ~"\ /^^|tf| ■||M 1^ ^* PI w^K^^ \ ■ m ' ^ ^^s^s^ Fig. 92. — Moth of the common stalk- borer, variety P. ntbris (X l\). 160 MANUAL OF VEGETABLE-GARDEN INSECTS other variety (P. nchris), there are three disthict white spots nearly one third the distance from the base of the wing, the middle one being the smallest (Fig. 92). Just inside the outer line near the front margin of the wing is a fine yellow crescent with a yellow spot lying within its concavity and with three to five white dots on its low^er and inner side. There is only one generation annually. Control. No satisfactory method of reaching the borers in their bur- rows is known. Much loss may be avoided, however, by de- stroying all rank weeds in which the caterpillars live growling in the vicinity of the garden and along the edges of fields planted to tomatoes, potatoes, corn and other plants especially subject to injury. References N. J. Agr. Exp. Sta. Rept. for 1905, pp. 584-587. 111. Agr. Exp. Sta. Bull. 95, pp. 374-377. 1904. Franklin, r2th Rept. State Ent. Minn., pp. 197-198. 1908. And in other papers published by Washburn. The Burdock Borer Papaipema cataphracta Grote Potato, tomato, rhubarb and corn have been reported in Canada as injured by a stalk-borer closely related to the species last treated. The insect ranges throughout the northern states and Canada westward to Minnesota. The favorite food plants of this caterpillar are burdock and thistle, but sunflower, ragweed, golden glow, hollyhock and many other ornamental plants are also subject to attack. The work of the borers becomes noticeable in July, specimens one third to full-grown being found till the first of August. The caterpillar is very similar to the common stalk-borer but the stripes run from end POTATO INSECTS 161 to end with no interruption in the middle. The caterpillars reach maturity in August and transform to brownish pup;e within the burrows. The moths are on the wing in September and October. They have an expanse of about 1-^ inches. The ground color of the front wings is light yellow, dusted with brown, the outer margin grayish, leaving a yellow^ spot at the apex. The outer line runs as in P. nifcia and is double and the wing is spotted in much the same way as in the variety nebris of that species. The hind wings are light brown. The eggs are deposited singly in cracks and crevices on the stems of the food plants in the fall but do not hatch until the follow- ing spring. There is only one generation annually. The injury inflicted by the burdock borer may be avoided by adopting the measures recommended for the common stalk-borer. The Potato Scab Gnat Pnyxia scabiei Hopkins Potatoes are sometimes injured by a small, white, black- headed maggot, about ^ inch in length, that causes an injury similar to that produced by the scab fungus. Outbreaks of this insect have been recorded in West Virginia and in Ohio and infested potatoes have been shipped from Philadelphia. The adult insects have been found in New York and have been collected under dead leaves in the woods in Missouri. It is probable that the normal food of the scab gnat maggot is de- caying vegetable matter. Under certain conditions, however, it will attack potatoes in the field and in storage. The maggots have also been found injuring peony bulbs in Pennsyl- vania. Potatoes are more subject to injury when grown in low ground where there is an abundance of humus or when stored in warm, damp cellars. The female fly is -^ to ^^ inch in length, pale in color and without wings. The male is somewhat dusky, smaller than M 162 MANUAL OF VEGETABLE-GARDEN INSECTS the female and occurs in two forms, one with normal functional wings and the other with abbreviated wings. The fly deposits her small, white, oblong eggs, about y^s "^ch in length, on the surface of the potato. The eggs hatch in five or six days and the young maggot works its way into the tuber, usually taking advantage of a scab spot or other injury. The maggots attack the healthy tissue and under favorable conditions of tempera- ture and moisture will continue their work generation after generation until the tuber is completely destroyed. The mag- gots become mature in about a week and then transform to delicate white pupte in flimsy silken cocoons either in the soil or on the surface of the tuber. The adults emerge in three or four days. From twenty to twenty-five days are required for the insect to complete its life cycle. Control. Serious injury by the potato scab gnat is of rare occurrence. Only uninfested seed potatoes should be planted and land on which the crop has been infected should not be used for potatoes the following year. Potatoes grown in dry, light soil are not likely to be attacked. References W. Va. Agr. Exp. Sta. Sp. Bull. 2, pp. 97-111. 1895. Hopkins, Proc. Ent. Soc. Wash., 3, pp. 149-159. 1895. The Potato Tuber Moth Phthorimcea operculella Zeller Potatoes in California and Texas are subject to attack by a small whitish caterpillar about ^ inch in length that riddles the tubers with burrows, causing them to decay. The potato tuber moth is also a troublesome tobacco pest and when feeding on this plant is known as the split-worm or tobacco leaf-miner. i POTATO INSECTS 163 The insect ranges from Virginia to Colorado and southward and on the Pacific Coast is present in CaHfornia and Washing- ton. It is also known as a serious enemy of the potato in Australia, New Zealand, the Mediterranean region and South Africa. Besides potato and tobacco, the insect sometimes attacks eggplant and tomato, mining the leaves and stalks and biuTowing in the fruit. Its wild food plants include com- mon nightshade, horse-nettle, Jamestown weed and several other solanaceous plants. The potato tuber moth has been studied most carefully in California and in France. The caterpillars not only infest the tubers both in the field and in storage but also mine the leaves and petioles and bore into the stalks. The parent moth has an expanse of a little more than ^ inch. The front wings are yellowish brown, more or less spotted and mottled with dark brown. The hind wings are light yellowish brown and provided with a long fringe. The moths appear in the field early in the spring and deposit their eggs singly, usually on the underside of the potato leaves. The egg is oval, about -^V inch in length, pearly white with a faint iridescence, becoming leaden gray just before hatching. The eggs hatch in three to five days. On hatching, the young larva bores into the leaf where it produces a blotch mine. As it increases in size, it may migrate to another leaf or bore down through the petiole and into the stalk, causing the branch to wilt and die. When full-grown the caterpillar is about ^ inch in length, white, tinged with pink or greenish above, with the head and cervical shield dark brown and with the small anal plate light brown. It reaches maturity in two weeks to seventeen days in warm weather. When ready to pupate, the larva constructs a small grayish silken cocoon about ^ inch in length, which is covered with dirt and pieces of excrement. The cocoons are sometimes found in the opening of the burrow, in trash at the base of the plant or more commonly in the dried leaves still clinging to the 164 MANUAL OF VEGETABLE-GARDEN INSECTS vine. The pupa is brown, becoming darker with age and is about f inch in length. The insect remains in the pupal stage from a week to ten days in warm weather. In two or three days after emergence, the moths lay eggs for another brood. Reproduction is continuous throughout the season. After the tubers have formed, they may become infested in several ways. Some of the caterpillars may leave the stalks and migrate to the potatoes. When the soil is loose and the potatoes are near the surface, the moths may work their way down through the cracks and lay their eggs on the tubers. When the potatoes are planted shallow some of the tubers may become exposed and the moths will lay their eggs on them. Potatoes are most likely to become infested at digging time. If left exposed in the field during late afternoon or overnight, eggs are laid on them in abundance. When the piles of pota- toes are covered with infested vines, the caterpillars may leave the stalks and enter the tubers. When infested tubers are placed in storage, the insect will continue breeding throughout the winter provided the temperature does not fall below 40° or 50° F. When deposited on the tubers, the eggs are usually placed around the eyes or on the edge of holes made by the larvse. On hatching the young caterpillar soon works its way into the potato, throwing out a small mass of frass through the opening. The young caterpillars at first burrow just underneath the skin but when half grown or more work their way into the flesh, sometimes quite to the center of the tuber. The burrow is lined with a silken tube through which the larva can move back and forth readily. When about to pupate, the larva leaves the tuber and in some crack or corner or be- tween two potatoes spins its cocoon. In storage the insect will continue to breed as long as any potatoes remain in con- dition to serve as food for the larvae. Five or six generations may develop in the course of a year. Under storage conditions, a longer period is required for the POTATO INSECTS 1G5 completion of the life cycle because of the lower temperature. Under such conditions the egg stage requires a week or ten days, the larva about six weeks and the pupa two weeks or over. Control. The injuries caused to the vines by the potato tuber moth are not in themselves serious. The great loss comes from the infested tubers. This may be prevented in large measure by planting the potatoes rather deep and by keeping them care- fully hilled so as not to allow any of the tubers to be exposed on which the moths can deposit their eggs. Care should be taken at digging time not to leave potatoes exposed overnight while the moths are laying. Piles of potatoes should not be covered with infested vines since the larvae will leave the stalks when they begin to wilt and enter the tubers. After the pota- toes have been placed in storage, they should be examined at frequent intervals and if any are found to be infested, they should be fumigated with carbon bisulfid at the rate of 2 pounds to 1000 cubic feet of space, allowing the fumigation to continue for about forty-eight hours. This should be re- peated at intervals of about a week in summer or two weeks in winter. Directions for fumigation will be found on page 380. Where the potato tuber moth is abundant, it is not advisable to plant potatoes on the same land for two years in succession. By practicing rotation of crops and by destroying all solaiia- ceous weeds on which the insect may breed, much loss may be avoided. References Cal. Agr. Exp. Sta. Bull. 135. 1901. Picard, Ann. Service Epiphyties, 1, pp. 106-176. 1913. U. S. Farm. Bull. 5.57. 1913. U. S. Dept. Agr. Bull. 59. 1914. U. S. Dcpt. Agr. Bull. 427. 1917. 166 MANUAL OF VEGETABLE-GARDEN INSECTS Other Potato Insects Corn ear-worm : 211 Southern corn root-worm : 222 Cabbage looper : 8 Garden webworm : 18 Seed-corn maggot : 36 Harlequin cabbage bug : 38 Serpentine leaf-miner : 4G False chinch-bug : 47 Yellow bear caterpillar : 357 Carrot beetle : 185 Adelphocoris rapidus : 195 Sugar-beet webworm : 97 Spinach apliis : 105 Tomato worms : 168 Western twelve-spotted cucumber beetle : 114 Belted cucumber beetle : 115 Southern leaf -footed plant-bug: 121 Garden springtail : 139 Grape colaspis : 67 Bean thrips : 69 Garden flea-hopper : 77 Eggplant tortoise beetle : 177 Eggplant lace-bug : 178 Spotted cutworm : 262 Greasy cutworm : 265 Dark-sided cutworm : 268 Striped cutworm : 270 Shagreened cutworm : 272 Clay-backed cutworm : 274 Variegated cutworm : 276 Army cutworm : 287 Fall army-worm : 292 Beet army-worm : 294 Yellow-striped army-worm : 295 Semi-tropical army-worm : 297 Striped blister-beetle : 302 Margined blister-beetle : 305 Gray blister-beetle : 306 Ash-gray blister-beetle : 306 Black blister-beetle : 307 Spotted blister-beetle : 309 Two-spotted blister-beetle : 309 J Macrobasis longicollis: 310 1 i POTATO INSECTS 167 Immaculate blister-beetle : 310 Segmented black blister-beetle : 310 Panther blister-beetle : 311 Crow blister-beetle : 311 Potato flea-beetle : 314 Western potato flea-beetle : 318 Tobacco flea-beetle : 319 Eggplant flea-beetle : 320 Pale-striped flea-beetle : 321 Red-headed flea-beetle : 323 Smartweed flea-beetle : 323 Hop flea-beetle : 335 Root-knot nematode : 338 MilUpedes: 342 Wheat wireworm : 348 Sugar-beet wireworm : 349 Slugs : 354 CHAPTER VII TOMATO INSECTS Many potato insects also attack the tomato. The most important of these are the potato flea-beetle and the Colorado potato beetle. In the South, the corn ear-worm is usually the most destructive pest to be contended with and the tomato worms often cause serious loss. The Tomato Worms Throughout the United States and southern Canada, tomatoes are subject to attack by large greenish or brownish caterpillars 3 or 4 inches in length which are provided with a sharp horn on the back near the hind end of the body. They are also known as horn-worms and tobacco worms. These tomato worms belong to two distinct species. The areas occupied by the two forms overlap to a considerable extent. Throughout the greater part of the United States, caterpillars of both species are found feeding together, the relative abundance varying from place to place and from year to year. The northern form ranges from Canada to Florida westward to the Pacific. The southern species breeds from Massachusetts, New Jersey, Ohio and Illinois southward through the West Indies to Patagonia. Both species occur in California. In addition to tomato, eggplant, potato and pepper are sometimes attacked. 168 TOMATO INSECTS 169 The northern tomato worm, PUegethontius quinquemaculata Haworth The adult of the northern tomato worm is a moth having an expanse of 4 to 5 inches (Fig. 93). The front wings are ashy ^*^^^:rfiS£W^ ^ y Fig. 93. — The northern tomato worm moth ( X J). gray marked with irregular brown and black lines. The hind wings are whitish with a broad gray band on the outer margin and crossed with four black bands, the middle pair being sharply zigzag. The abdomen is gray marked with a narrow median black line and with a row of large yellow spots on each side which are surrounded with black. On the posterior margin of each segment are two white spots on each side, one above and one below the yellow spot of the succeeding segment. The moths appear on the wing in May or June. They fly in the evening or on dark days and may be seen hovering over flowers Fig. 94. — Egg of the northern tomato worm (X 7). 170 MANUAL OF VEGETABLE-GARDEN INSECTS from which they suck the nectar. The mouth is provided with a long sucking tube from 2^ to 5 inches in length which when not in use is coiled under the head. The eggs are deposited singly, usually on the underside of the leaves. The. egg (Fig. 94) is globular, nearly ys inch in diameter and greenish yellow Fig. 95. — Full-grown northern tomato worm (X I). in color. The eggs hatch in three to eight days and the young caterpillars begin feeding on the leaves. They grow rapidly, reaching maturity in three weeks to a month. The larger caterpillars feed ravenously and will strip a tomato vine in a few days. The full-grown caterpillar (Fig. 95) is 3 or 4 inches in length and varies in color from green to dark brown. Each segment of the abdo- men is marked on the side just above the spiracle with a greenish white oblique stripe which, with a similar horizontal stripe below the spiracle, forms a V with the apex pointed forward. The horn at the posterior end of the body is green with the sides black. When disturbed the caterpillar has the curious habit of elevating the front part Fig. ' (Fig. 109) , , , , „ ^ ., has an expanse of 3-^ Fig. 109. — The black swallow-tail / • i mi. butterfly (x^). to nearly 4 mches. Ihe INJURIOUS TO CARROT AND RELATED CROPS 187 Fig. 110. — Eggs of the black swallow-tail butterfly (X 12). male is somewhat smaller. The wings are black with two rows of yellow spots crossing both wings with a marginal row of yellow lunules. Be- tween the rows of yel- low spots on the hind wing and on the hind part of the front wing is a bluish band. On the posterior angle of the hind wing is an orange spot with a black center. In the male the yellow markings are Fig. 111. — The black swallow-tail butterfly, a young caterpillar and one nearly full- grown with the osmateria protruded ( X |) . 188 MANUAL OF VEGETABLE-GARDEN INSECTS Fig. 112. — Caterpillar of the black swallow- tail butterfly suspended for pupation (X f). more distinct and on the hind wing the inner row of spots is replaced by a broad yellow band. In the North the butterflies emerge from over-wintered pup?e in May and June and deposit their eggs singly on. the upper side of the leaves of the host plants. In Florida the butterflies hibernate. The egg (Fig. 110) is globular, about -^ inch in diameter, pale honey-yellow when first laid, changing to reddish brown in parts. The eggs hatch in about ten days. In the first stage the caterpillar is about Y^ inch in length, black, banded about the middle and rear end with white. When mature the caterpillar is about 2 inches in length, green, and each segment has a black band near the front margin inclosing six yellow spots. When disturbed this caterpillar has the habit of extruding a pair of orange-red horn-like scent organs from the dorsum of the prothorax (Fig. 111). These organs are known as osmateria and are probably for defense. The caterpillars become full-grown in three to four weeks and suspending themselves by a silken girdle (Fig. 112) transform to pupae on some nearby support. The pupa (Fig. 113) is 1-^ inches in length, light dirty brown marked with black and dark green. It is attached to its support by a button of silk at the hind end of the body Fig. 113. — Chrysalis of the black swallow-tail butterfly (X ft)- INJURIOUS TO CARROT AND RELATED CROPS 189 and held in place by a silken girdle around the thorax. The pupal period lasts from nine to sixteen days. There are two broods in the North and at least three in the South. In California the black swallow-tail butterfly is replaced as a celery and parsley pest by a related species, Papilio zoHcaon Boisduval. Control. As this insect rarely becomes abundant, it may be usually held in check by hand-picking the caterpillars. Reference Scudder, Butterflies of Eastern U. S., 2, pp. 1353-1364. 1889. The Celery Leaf-Tyer Phlyctcenia ferrugalis Hiibner Celery is occasionally injured by a small greenish caterpillar that folds or webs together the leaves and sometimes bores down into the stalks. This in- sect is widely distributed in Europe, Asia and North America. In the United States it has been reported injuring celery, spinach and beet but is best known as a greenhouse pest, attacking a wide variety of hot-house plants. Its wild food plants include boneset, hedge nettle, strawberry Fig. 114. — The celery leaf-tyer, caterpillar (X 3i). 190 MANUAL OF VEGETABLE-GARDEN INSECTS Fig. 115. — The celery leaf-tyer, pupa ( X 5). and burdock. The caterpillars have been occasionally found feeding on celery and beet in August and September. The full-grown caterpillar (Fig. 114) is f inch in length, trans- lucent greenish white with a pair of black spots on the cervical shield. The body is marked with a dark green median stripe bordered by a much wider greenish white one. When disturbed the caterpillar has the habit of wriggling actively back and forth. The larva generally feeds openly on the under surface of the leaves, but sometimes it forms a retreat by webbing together several leaves loosely with silk. Under greenhouse conditions, the cater- pillars mature in about three weeks. Pupa- tion takes place within thin white, silken cocoons spun within folded leaves. The pupa (Fig. 115) is a little less than ^ inch in length and dark brown or black. The pupal period varies from twelve to twenty days, the moth did not emerge until a year after the pupa was formed. The moth (Fig. 116) has an expanse of about ^ inch and is rusty brown with somewhat obscure blackish markings on the front wings. The flight of the moths is short and jerky and on alighting they quickly hide on the underside of the object. The small, flat, elliptical, translucent eggs (Fig. 117), Fig. 117. — Eggs of the ^^°"* '^ "^^^ "^ diameter, are deposited celery leaf-tyer (X22). on the underside of the leaves in small Fig. 116.— The cel- ery leaf-tyer moth (X 1|). In one instance INJURIOUS TO CARROT AND RELATED CROPS 191 clusters of two to twelve, often overlapping. The eggs hatch in twelve to fourteen days. Under greenhouse conditions, there are from seven to eight generations annually ; in the open there are said to be only four. The celery leaf-tyer has never been found causing serious injury in the open and no methods of controlling it under such conditions have been devised. References Buckler, Ent. Mo. Mag., 14, pp. 200-204. 1878. Fletcher and Gibson, Can. Ent., 33, pp. 140-144. 1901. Cornell Agr. Exp. Sta. Bull. 190, pp. 159-164. 1901. The Celery Looper Autographa falcigera Kirby Throughout the United States and southern Canada east of the Rocky Mountains, celery, lettuce and sugar-beets are some- times subject to the attack of a looping caterpillar. These caterpillars hibernate in a partly grown condition and com- plete their development in early spring. The full-grown larva is \^ inches in length, pale translucent green in color, and marked with a median dark line, on each side of which are three light lines. The stigmatal stripe is white bordered above by a dark green stripe. The spiracles are white, dis- tinctly ringed with black, a character by which it may be dis- tinguished from the cabbage looper. The body becomes gradually larger towards the posterior end, which is obliquely truncate. Although these caterpillars are closely related to the cutworms, they crawl with a peculiar looping motion owing to the absence of prolegs on the third and fourth abdominal segments. In Illinois the over-wintered caterpillars become mature in late April and pupate in silken cocoons. The pupal period occupies nine or ten days. 192 MANUAL OF VEGETABLE-GARDEN INSECTS The moth has an expanse of about 1^ niches. The front wings are purplish brown with an obHque band in the front angle and the area back of the silver spot velvety reddish brown. The silver mark is distinct and the hind margin of the front wing is scalloped so as to leave a rounded projection at the 1 hind angle. The hind wings are ■1 ^ - j^^^ yellowish brown, darker toward the ^H|^^|gA|^^|^^H^ margin, which is edged with white . ^(^^Bfl||^^|r '^^^^ ^gg is about gV ^^ch in ^^^ ^ ^^^ diameter, milky white, globular, slightly flattened and marked with Fig. 118. — Moth of the celery delicate longitudinal ridges. The looper (X U). I, ^ -u ' I. ^ i eggs hatch m about a week. In Illinois there are apparently three broods annually, the moths flying in April and early I\Iay, in late July and early August and again in late September. The caterpillars of the summer brood require about three weeks to reach maturity. The celery looper does not often occur in sufficient numbers to require remedial measures. As arsenicals cannot be used on celery or lettuce, hand-picking the caterpillars is the only measure available and will usually be found sufficient. Reference Coquillett, 11th Rept. State Ent. 111., pp. 38-43. 1882. The Tarnished Plant-Bug Lygus pratensis Linnaeus The tarnished plant-bug is one of the commonest insects found on garden plants. It feeds on a great variety of trees, shrubs and herbs, showing a special liking for opening buds, flowers and tender new growth. It is widely distributed through- out the entu*e north temperate zone. The adult (Fig. 119) is an INJURIOUS TO CARROT AND RELATED CROPS 193 Fig. 119. — The tarnished plant-bug, adult ( X 4|). inconspicuous, brownish bug mottled with various shades of reddish and yellowish brown, ^ to ^ inch in length. The bugs are shy, taking flight at the slightest alarm, and are often over- looked by the gardener. This insect hibernates as an adult in leaves, grass, stone piles and under other rubbish. The bugs emerge in early spring and are then often destructive to the buds of fruit-trees and nursery stock. They are also to be found abundantly in mullein rosettes and as soon as the days become warmer they begin feeding on various weeds. In New York the eggs become mature in the over-wintering females by the last of April or the first cf iNIay and a generation of young is produced, giving rise to a new brood of adults the latter part of June. The egg (Fig. 120) is nearly ^ inch in length, flask-shaped and obliquely truncate at the anterior end. The eggs are in- serted their full length into the tender tissue of the plant. They have been found in the petioles of peach leaves, the blossom buds of dahlias, the seed-stalks, stems and leaves of volunteer turnips and later in the season in the heads of com- posite plants such as daisies and asters. They hatch in about ten days. The nymphs are yellowish green to greenish, marked on the thorax with four black spots. In the older nymphs the thorax and wing-pads are variously mottled with brownish (Fig. 121). In late summer and fall the nymphs are very abundant on wild carrot, goldenrod and wild asters. There Fig. 120. — Eggs of the tar- nished plant-bug in position in tender peach tip (X 11). 194 MANUAL OF VEGETABLE-GARDEN INSECTS Fig. 121. — The tar- nished phint-bug, fifth stage nymph of the plant attacked. In the case of potatoes, the in- jury is similar to that produced by several other insects and is known as tip-burn. This is most serious in years of drought. The bugs sometimes puncture bean pods, arresting growth at the point of injury. In the case of beets the punctures cause a curling or kinking of the leaves (Fig. 122) and in severe cases a stunting of the plants. The bugs often attack celery plants that are five nymphal stages, the insect becom- ing mature at the fifth molt. The life cycle requires from twenty-five to thirty days, and there are probably four or five genera- tions annually. Most of the injury to cultivated plants is caused by the feeding punctures of the adults, since most of the nymphs are to be found on weeds. In feeding, the bug punctures the plant with the sharp needle- like bristles of its beak and sucks out the juices, at the same time apparently inject- ing some substance poisonous to the tissue. The character of the injury varies with the nature Fig. 122. — Beet leaf kinked by the tarnished plant-bug. INJURIOUS TO CARROT AND RELATED CROPS 195 Fi(i. 12.3. — Ad( I phocoris rapidus, adult (X 5j). are blanching, puncture the tender stalks, producing large brown wilted spots and a blackening of the tissue at the joint. This trouble is known among celery-growers as black joint. The injury mars the appearance of the plants, lessens their market value and causes considerable loss. Cab- bage, cauliflower, turnip, salsify and cucumber are also subject to attack, but serious injury to these plants is of rare occurrence. It is rarely possible to prevent attack by the tarnished plant-bug because the injury is inflicted by the adults that have developed on wild plants, common weeds that are everywhere present. They are too active to be hit by a spray and so resistant to insecticides that it is impossible to kill them with- out using some material that would injure the plants. Clean farming is often recommended as a means of reducing the numbers of the bugs, but under circumstances gives little relief. Another plant-bug, Adclphncoris rajjidiis Say, is often associated with the tarnished plant-bug, feeding on potato, sugar-beets, cel- ery and cotton. It also feeds on numerous Fig. 125. — Add phocoris mpi- weeds and is sometimes ^"*' ^^*^ '^'^^^ ""^'"^^^ ^^ ^^• injurious to the fruit of the strawberry. The adult (Fig. 123) is a little over -^ inch in length. The head, legs and prothorax are yellow ; there are two black spots near the hind margin of Fig. 124. — Egg of Adelphocoris rapidus (X 23). 196 MANUAL OF VEGETABLE-GARDEN INSECTS the prothorax and the wings are dark brown except the edge, which is narrowly bordered with yellowish. The* antennae are black, broadly ringed wdth yellowish white. The life history is similar to that of the tarnished plant-bug and the eggs are deposited in similar places. The egg is also similar but bears a small spine at the edge of the cap (Fig. 124). The insect passes through five nymphal stages. The nymphs are gayly colored with green, red and various shades of brown (Fig. 125) and are found abundantly throughout the growing season. Reference Cornell Agr. Exp. Sta. Bull. 346. 1914. The Negro-Bug Thyreocoris pulicarius Germar A serious outbreak of this small black stink-bug occurred in the celery fields of Michigan in 1893, causing a loss of many thousand dollars. A similar outbreak took place in northern Ohio in 1906. It is surprising that attacks of this kind have not been more frequent, since the bugs are often abundant on their wild food plants over large areas every year. The insect ranges throughout the United States and Canada east of the Rocky Mountains southward to Florida and Arizona. The adult (Fig. 126) is about ^ inch in length, shining black, strongly convex, short and broad, widest on the thorax The scutellum is greatly developed and covers the abdomen; the exposed edge of the wing is yellowish white. The insect hibernates in the adult condition and the bugs Fig. 126. — The negro-bug, adult (X 14). and rounded behind. INJURIOUS TO CARROT AND RELATED CROPS 197 appear on their food plants in the spring. In IlHnois the eggs are laid in May and June. They are deposited singly on the leaves. The egg is :^ inch in length, elongate, shining, light orange when first laid but deepening to bright red just before hatching. The egg has been observed to hatch in sixteen days. The older nymph is similar to the adult but has the abdomen blood-red. The nymphs become mature in July and the adults, after feeding for a few weeks, go into hibernation rather early. The insect breeds abundantly on various weeds, including beggar-ticks, tick-seed, red-root, ground-nut, great lobelia and neckweed (Veronica peregrinaf). It has also been found injurious to corn, wheat and grass and the bugs often give an unpleasant flavor to raspberries and strawberries. There is only one brood developed annually. The injury to celery has been caused almost entirely by the adults. They congregate in clusters at the base of the petioles on the highest stalks and suck out the sap, causing the leaves to wilt and die. Later they attack the lower leaves at the center of the plant. Celery so injured is stunted and the stalks more or less deformed, and much of it is rendered unsuitable for market. When infesting celery, the negro-bug can best be controlled by spraying with "Black Leaf 40" tobacco extract, 1 pint in 100 gallons of water in which 5 to 6 pounds of soap have been dissolved. Much may be accomplished in preventing attack by keeping down all wild plants on which the insect may breed. Reference Mich. Agr. Exp. Sta. Bull. 102, pp. 13-18. 1893. The Parsnip Webworm Depressaria heracliana Linnaeus In growing parsnip and celery seed, much trouble is often experienced from the depredations of small greenish yellow 198 MANUAL OF VEGETABLE-GARDEN INSECTS caterpillars that web together and devour the unfolding blossom heads. The insect is widely distributed in Europe and eastern North America. It feeds on wild parsnip, wild carrot and other umbelliferous plants. The insect hibernates in the adult stage. The small grayish moths are found under flakes of bark, in crevices, or in similar situations. The moth has an average expanse of about an inch. The front wings are brownish gray marked with inter- rupted longitudinal dark lines and a small black spot near the center. The hind wings are pearl-gray. Over-wintered speci- mens are usually much rubbed and are much lighter in appear- ance. The moths deposit their eggs singly in May, June and July on the leaves, stems and particularly on the sheath sur- rounding the flower-head. The egg is elongate, oval, pearly white, ribbed longitudinally, and about ^V inch in length. The eggs hatch in about seven days and the young caterpillars enter the flower-buds, where they feed, webbing them together with silk. When the flower-cluster opens, the caterpillars re- main in the protection of the web and continue to feed on the flowers and later on the seeds. They become full-grown in four to five weeks. The mature caterpillar is about f inch in length, greenish yellow above, lighter yellow on the sides and beneath. The head, cervical shield and thoracic legs are shiny black. The body is sparsely clothed with hairs arising from small black warts. When nearly mature, the caterpillars leave the flower-heads and burrow into the stems, usually in the axils of the leaves. After entering the stem, the caterpillar feeds for a short time and then constructs a slight cocoon of silk and excrement in which pupation takes place. The pupa is about ^ inch in length, with a dark brown thorax and light brown abdomen. The moths emerge in about three weeks and soon go into hiber- nation in sheltered places. No practical method of controlling this insect has been de- INJURIOUS TO CARROT AND RELATED CROPS 199 vised. After the flower-heads have opened, many of the caterpiHars may be destroyed by spraying or dusting with an arsenical. References Riley, Insect Life, 1, pp. 94-98. 1888. Mich. Agr. Exp. Sta. 3rd Rept., pp. 112-115. 1890. Brittain and Gooderham, Can. Ent., 48, pp. 37-41. 1916. The Parsnip Leaf-Miner Acidin fr atria Loew Sometimes the leaves of parsnip are disfigured by the mines of a small whitish maggot. This insect is never very abundant but is widely distributed throughout the whole United States and is probably identical with the European celery fly, Aridia hcraclci Linnseus. The greenish translucent maggots are found in the leaves from May till July, where they produce blotch mines. Several larvae occupy the same leaf and the mines coalesce. The mines are most abundant on the lower leaves or on plants grown in partial shade. \Yhen mature, the maggots are a little over i inch in length. They transform to straw- colored puparia usually within the mine, and the flies emerge in about two weeks. The fly is about ^ inch in length. The head, thorax and legs are pale yellow and the abdomen green. The wings are beautifully marked with yellowish brown curved bands. The number of generations annually has not been definitely determined. Reference U. S. Bur. Ent. Bull. 82, pp. 9-13. 1909. The Parsley Stalk- Weevil Listronotus latiusculns Boheman This insect has been recorded as injuring parsley planted on low land in Virginia and in coldframes in Connecticut. The 200 MANUAL OF VEGETABLE-GARDEN INSECTS larvae were found boring in the stems and roots, causing the death of the plant. This weevil breeds normally in the heads and stalks of the common arrowhead, a plant found growing in low, wet ground. Its attack on parsley was apparently more or less incidental. Other Carrot, Celery and Parsnip Insects Cabbage looper : 8 Yellow bear caterpillar : 357 Spinach aphis : 105 Garden springtail : 139 Bean aphis : 76 Garden flea-hopper : 77 Spotted cutworm : 262 Striped cutworm : 270 Variegated cutworm : 276 Spotted-legged cutworm : 282 Army cutworm : 287 Army-worm : 288 Striped blister-beetle : 302 Black blister-beetle : 307 Potato flea-beetle : 314 Pale-striped flea-beetle : 321 Root-knot nematode : 338 Millipedes: 342 Wheat wireworm : 348 Slugs: 354 CHAPTER X ASPARAGUS INSECTS The important insects infesting asparagus arc relatively few in number, and, like their host plant, are of European origin. The Common Asparagus Beetle Crioceris asparagi Linnaeus This common beetle is a native of Europe and was first found in this country at Astoria on Long Island in 18G0, although it had probably been present in that locality for several years. The insect has gradually extended its range until it is now widely distributed from North Carolina to Massachusetts and Canada and westward to Illinois. It was introduced into California about 1904 and is now widely spread throughout the central part of the state. It has also been reported from Colorado. The asparagus beetle (Fig. 127) is about -J inch in length. The head, under parts, legs and antenna? are bluish black frequently tinged with green. The tibiae are reddish at base. The thorax is reddish usually with two black spots near the center. The markings on the wing- 201 Fig. 127. — The com- mon asparagus beetle (X5). 202 MANUAL OF VEGETABLE-GARDEN INSECTS covers vary greatly even in specimens from the same locality. The inner margin of each wing-cover is bluish black ; the outer margin and the tip are orange. The intervening space is yellowish white broken into three spots by bluish black bands which are usually connected with the inner marginal stripe. In some cases these bands are broken into spots. Sometimes the two wing-covers on the same insect are not marked alike. Varia- FiG. 128. — Diagram to show variations in the tions in the pattern pattern on the wing-covers of the common aspar- , . ,-,. agus beetle. are shown m Fig. 128. There is a tendency in the South for the beetles to be lighter in color. The beetles pass the winter under any convenient shelter such as piles of rubbish, under the bark of trees or in similar situations. They have often been found in great numbers in heaps of old asparagus roots where the field has been plowed up. The beetles emerge from their winter quarters at the time the young shoots are just coming up. They attack the tender tips, eating out holes and producing a brownish discolora- tion of the tissue. When abundant the crop may be seriously damaged. The beetles soon begin to lay their eggs on the young shoots. The egg (Fig. 129) is elongate oval, blackish brown and about ^ inch in length. The eggs are laid on end singly or in rows from two to eight. Early in the season they are laid on the tips, but later are attached to the leaves and flower- stems. The eggs hatch in three to eight days and the young Fig. 129. — Eggs of the common asparagus beetle (X 6). ASPARAGUS INSECTS 203 grubs begin feeding on the tender tips. The body of the newly hatched larva is gray and its head and legs are black. The grub becomes mature in ten days to two weeks. It is then about yV i"t'h in length, dark gray in color, with the head and legs shining black. On the segment behind the head there are two shining black spots. The abdominal segments are provided with prolegs which are used by the grub in maintain- ing its hold on the plant (Fig. 130). When mature the grubs fall to the ground and there just below the surface construct a small earthen cell within which they transform to pale yellow- ish pupae. Transformation to the beetles takes place in about a week, although in cool weather the pupal period may be much longer. In England the insect remains in the pupal state from fourteen to twenty days. After trans- formation the beetles require three or four days to harden before they are ready to make their appear- ance above ground. The entire life cycle requires from three to seven weeks depending on the climate. In the North there are at least two generations annually and in the South there are said to be four or five. In addition to the injury to the tender shoots in the spring, the beetles and larva^ seriously damage the plants after they have leafed out. Both beetles and grubs feed on the leaves and the epidermis is chewed from the stem. In this way the growth of the plants is seriously checked and the proper develop- ment of the roots is prevented. Plants stunted in this way are not able to send up large and vigorous shoots, and the size and quality of the crop are decreased. The common asparagus Fig. 130. — Full-grown larva of the common a.sparagus beetle (X 4j). 204 MANUAL OF VEGETABLE-GARDEN INSECTS beetle is very troublesome in newly set beds. Frequent de- foliation weakens the plants, making it difficult for them to become established. The common asparagus beetle is held in check by a small Chalcid parasite, Tetrastichus asparagi Crawford, the life his- tory of which is remarkable. The adult parasite appears in the asparagus field in the spring while the eggs of the beetle are being laid. The female inserts her eggs in those of the beetle. The beetle egg hatches and its larva, containing the larvae of the parasite, reaches maturity, enters the ground and constructs its pupal cell but does not pupate. The parasites then complete the destruction of the host and emerge from its shriveled remains, pupate within the cell constructed by the beetle larva and later emerge as adults. From one to ten para- sites have been reared from a single beetle larva. Methods of control. In asparagus fields in which the crop is being cut for market, the injury to the young shoots by the larNie may be prevented by cutting the crop clean every three to five days. In this way all the eggs deposited on the shoots will be removed before or very soon after hatching. All volunteer plants should be de- stroyed but it will often pay to leave a row here and there uncut to serve as a trap on which the beetles will congregate, feed and lay their eggs. Here they may be poisoned with arsenate of lead (paste), 1 pound in 20 gallons of water, or the plants may be cut and burned, thus destroying the early stages of the beetle. After the cutting season is over, the plants may be protected from beetle injury by two or three applications of arsenate of lead (paste), 1 pound in 20 gallons of water. It is not an easy matter, however, to spray thoroughly a large field of asparagus when the plants have made a heavy growth. In newly set beds, spraying with arsenate of lead is often re- sorted to with satisfactory results. In this case the application ASPARAGUS INSECTS 205 should be made early in order to destroy the first brood of beetles and larvte and thus give the plants a chance to make a strong growth early in the season. The use of poultry for the destruction of the beetles was advised by T. W. Harris nearly eighty years ago. This method of control is still practiced with good results in some localities. The asparagus field is surrounded with a chicken-wire fence, and poultry are allowed the run of the field. Thirty or forty hens are sufficient to keep a two-acre field practically free from the beetles during the early part of the season. When the plants grow up, some of the beetles wall keep out of reach and they may become abundant in the fall. It is rarely necessary, however, to resort to spraying in fields in which poultry are allowed to run. In the home garden the larvse may be de- stroyed by dusting the plants with hydrated lime or land plaster. References Fitch, 8th Kept. State Ent. N. Y., pp. 177-186. 186.3. Lintner, 1st Kept. State Ent. N. Y., pp. 239-246. 1882. Board Agriculture [England] Leaflet 47. 1902. Chittenden, Yearbook U. S. Dept. Agr., pp. .341-349. 1896. Johnston, .Jour. Agr. Research, 4, pp. 303-314. 1915. Parasite. Sajo, Prometheus, 13, pp. 166-171. 1902. U. S. Farm. Bull. 837. 1917. The Twelve-Spotted Asparagus Beetle Crioceris duodecimpunctata Linnseus In this country, the twelve-spotted asparagus beetle (Fig. 131) was first noticed in 1881 in ^laryland. It gradually spread northward, reaching New Jersey in 1892, New York in 1893 and Canada in 1898. Its range now extends from Maine to the Niagara peninsula in Canada and southward to Virginia. This beetle is most injm'ious early in the season when the 206 MANUAL OF VEGETABLE-GARDEN INSECTS adults attack the growing tips and sometimes eat the buds as soon as they appear above the ground. The beetles also feed on the foliage and eat out irregular areas in the bark of the stems. The larvae cause very little injury since they feed almost entirely inside the berries. The insect passes the winter in the adult condition, hidden away in dry, sheltered places. The beetles leave their winter quarters about a week later than the common asparagus beetle. They feed on the tender asparagus shoots in much the same way but do not deposit their eggs until about the time the plants begin to blossom or from three weeks to a month after appearing in the field. The twelve-spotted asparagus beetle is slightly larger and more robust than the other species. Its general color is reddish orange. The antennae, eyes, knees, tarsi and the underside of the thorax are black. On each wing-cover there are six distinct black spots. The eggs are deposited singly on the leaves of asparagus plants, usually those bearing fruit. The egg (Fig. 132) is about -^ inch in length by -q\ inch in width and is pointedly rounded at each end. The surface is smooth, shin- ing and without apparent sculp- ture. When first laid, the egg is nearly white, changing through yellow or orange to light green or brownish olive. It is attached to the leaf by one side. The eggs hatch in a week to twelve days. The young larva is about -^ inch in length, pale yellow or orange in color, with the head, legs and a spot on each side of the first segment black. The young larva feeds Fig. 131. — The twelve- spotted asparagus beetle (X 5). Fig. 132. — Egg of the twelve- spotted asparagus beetle (X 12). I ASPARAGUS INSECTS 207 very little if at all on the foliage but wanders about till it finds a berry, which it enters usually at the blossom end. The lar\-a feeds on the seeds and migrates from berry to berry until full-grown. Sometimes three or four berries are attacked by a single larva. In the course of its develop- ment, the larva passes through three stages. When full- grown it is about -j inch in length and varies in color from light orange to brownish yellow. The legs and two spots on the jjrothorax are black. The larva becomes mature in three to four weeks. It then descends to the ground, where just below the surface it spins a tough silken cocoon into which particles of dirt are incorporated. In about two days after building its cocoon, the larva transforms to a yellowish pupa and in twelve to sixteen days the transformation to the adult takes place. In New York the beetles of the second brood appear in July and lay eggs for a second generation. The beetles of the next brood emerge in August and September and go into hibernation with the advent of cold weather. There are two generations annually in the North. In Europe two other beetles attack asparagus, the fourteen- spotted and the five-spotted asparagus beetles {Crioceris qua- t iiordecimpunctata and C. quinquepunctata). The larvae of both species are said to feed on the foliage in much the same way as the larva of the common asparagus beetle. Methods of control. Since the larvae live inside the berries, they cannot be reached with an arsenical poison but the beetles may be killed by spray- ing with arsenate of lead as suggested for the control of the common asparagus beetle. References Lintner, 12th Kept. State Ent. N. Y., pp. 248-252. 1897. Sajo, Prometheus, 13, pp. 166-171. 1902. Cornell Agr. Exp. Sta. Bull. 331, pp. 422-435. 1913. U. S. Farm. Bull. 837. 1917. 208 MANUAL OF VEGETABLE-GARDEN INSECTS The Asparagus Miner Agroinyza simplex Loew {Agromyza maura var. simplex Loew) In the present state of knowledge of this group of flies, it is impossible to indicate with any accuracy the geographical dis- tribution of this species. There are several closely related forms in the genus Agromyza considered as distinct species by some authors and as varieties of Agromyza maura Meigen by others. The asparagus miner belongs to this group. As the haljits and early stages of most of these varieties or species are still unknown and as it is very difficult to distinguish them from a study of the flies alone, it is at present impossible to determine the actual range of this pest. In America Agromyza simplex has been recorded from Massachusetts, Ontario and Illinois and southward to Georgia. It also occurs in central California. It has been reared in France and the flies have been captured in England and Germany. What is apparently the same species but deter- mined as Agromyza maura was reared from aspara- gus in Hungary. The adult of the aspara- gus miner (Fig. 133) is a small, metallic, black, two-winged fly, |^ to |^ inch in length and having an expanse of 3- to -j inch. In New York the flies appear from the middle to the last of May. In about a week after emerging, the female inserts her eggs just under the epidermis of the asparagus stalk near Fig. 133. — The asparagus miner, adult (XS). ASPARAGUS INSECTS 209 the ground. The egg is elongate oval, slightly wider at one end and somewhat pointed at the other. It is about 5V inch in length and when first laid is glistening white in color. The eggs hatch in twelve to eighteen days and the young maggot begins to mine just under the epidermis. At first the larva works upward, following a more or less sinuate course, but when nearly mature it turns downward towards the base of the plant. In the case of the first brood, pupation may take place aboveground but the maggots of the second generation usually w'ork down from one to seven inches below the surface before transforming. The full-grown maggot is creamy white in color and is ^ to ^ inch in length. The maggots attain their growth in two or three weeks and transform into puparia within the mine. The puparium is ^ to ^ inch in length and brownish in color, becoming darker with age. The insect remains in this stage for two to three weeks and the flies of the second brood begin to emerge the latter part of July. The maggots of the second brood are most abundant in their mines during August but both maggots and flies are present until frost. The winter puparia are formed in late August and September. These are found under the epidermis of the stems below ground. There are two generations annually. When, as is often the case, several maggots infest a single stem, their mines cross each other, thus girdling the shoot. Stems injured in this way take on a sickly yellowish appearance and die prematurely, thus weakening the plants to a consider- able extent. Methods of control. The asparagus miner rarely does enough damage to warrant commercial growers making any serious efforts to control it, and no remedial measures satisfactory for commercial condi- tions have been devised. The insect causes little or no trouble in beds that are being cut, its injuries being chiefly confined to 210 MANUAL OF VEGETABLE-GARDEN INSECTS new beds. It has been recommended to pull up and burn infested stalks in the fall after frost or in the spring and thus destroy the over-wintering puparia. This is a laborious opera- tion and, as many of the stems are broken off, enough puparia will be left to reinfest the field. It has also been suggested that the flies might be killed with a sweetened poison bait but as this method has not been tried under field conditions its value is very doubtful. References N. Y. (Geneva) Agr. Exp. Sta. Bull. 189. 1900. U. S. Bur. Ent. Circ. 135. 1911. Cornell Agr. E.xp. Sta. Bull. 331, pp. 411-421. 1913. Other Asparagus Insects Corn ear-worm : 211 Southern corn root-worm : 222 Stink-bugs: 232 Cabbage looper : 8 Harlequin cabbage bug : 38 Yellow bear caterpillar : 357 Belted cucumber beetle : 115 Southern leaf-footed plant-bug : 121 Melon aphis : 135 Potato aphis : 150 Bean aphis : 76 Greasy cutworm : 265 Black army-worm : 275 Variegated cutworm : 276 Yellow-striped army-worm : 295 Root-knot nematode : 338 CHAPTER XI CORN INSECTS The insects feeding on Indian corn are nnmerous, over two hundred species having been recorded as more or less injurious to some part of the plant. The roots are injured by wire worms, white grubs, corn root-worms, by the larvae of bill-bugs and are infested by the corn root-aphis. The young plants are fre- cjuently eaten off by cutworms, the leaves riddled by flea- beetles and the crown tunneled by the stalk-borers. The unripe ears are attacked by the ear-worm, which is the most important insect infesting sweet corn. In this chapter no attempt is made to give a comprehensive account of the insects injurious to field corn ; only the more important species are treated and only those most likely to attack sweet corn. The Corn Ear-Worm Heliothis obsoleta Fabricius The corn ear-worm ranges throughout the United States and southern Canada, southward through ^Mexico and the West Indies to Argentina. In the Old World it is found throughout Africa and Europe eastward to China, India, the East Indies, Australia and New Zealand. In the southern states, this insect is a serious enemy of cotton and is there known as the cotton boUworm. Corn is the favorite food plant of this 211 212 MANUAL OF VEGETABLE-GARDEN INSECTS insect, serious injury to this crop being of annual occurrence from the vicinity of New York City southward east of the Appalachian ^Mountains ; from Ohio, Illinois, Nebraska and Montana southward to the Gulf and in the warmer parts of the Far West. It occurs in the greatest abundance, however, and is most destructive in the cotton belt. From New Jersey southward, the corn ear-worm is considered the worst insect pest of tomatoes, and peas and beans are also subject to serious injury. Among tobacco-growers the insect is known as the bud-worm from its habit of boring into the roll of unopened leaves at the center of the plant. Other plants liable to more or less serious injury are okra, pepper, eggplant, pumpkin, squash, melon, cucumber, asparagus, peanut, coUards and potatoes. The insect also attacks sorghum, sugar-cane, millet, cowpeas, vetch, alfalfa and clover. Its wild food plants are numerous ; some of the more common are Jamestown weed, ground cherry, wild sunflower, cocklebur, bindweed, horse- nettle, velvet-leaf and hemp. Many ornamental plants are also attacked, such as gladiolus, geranium, mignonette, morning- glory and rose. When driven by hunger, the caterpillars will feed on almost any succulent vegetation they can find. Ripen- ing fruits, such as peaches, plums and even quinces, are some- times attacked. Throughout the greater part of the United States and Canada, the corn ear-worm hibernates in the pupal stage, but in southern Florida some of the moths remain active during the winter. The moths emerge in early spring over a period of at least a month. The moth has an expanse of about 1^ inches. In the commonest form, the front wing is straw-color, usually marked with a spot in the middle and frequently with a darker area near the tip. The spots may be entirely lacking or the wing may be heavily shaded with brown, and the wings are sometimes tinged with reddish or greenish. The hind wings are creamy white with a diffuse blackish border containing a CORN INSECTS 213 pale spot and there is usually a dark spot near the middle of the wing. The flight of the moths is low, swift and irregular. They lay their eggs mostly on dark days or at dusk. The eggs are deposited singly on the leaves and stems of tomato, tobacco and cotton, and on the leaves, tassels and silk of corn, the last being preferred above all others for oviposition. Each female is capable of laying from 500 or ()()0 to over 2500 eggs. The egg (Fig. 134) is a little less than -^^ inch in diameter, waxy white, faintly tinged with yellowish, nearly globular, with the base flattened and the tip- depressed. The surface is marked with a series of ridges radiating from the tip. The first moths usually appear in the spring and are ready to lay their eggs before corn is a\'ailable. Under such cir- cumstances, eggs are deposited on early to- matoes, peas and beans. The time required for the hatching of the eggs varies with the temperature. In April they hatch in about a ^^^i V^'*- ~ ^^^ ' , . , , of the corn ear- week, m the summer m two or three days worm(x30). and in the late fall in two weeks or over. The newly hatched larva is a little over -^ inch in length, nearly white, with the head and cervical shield black and the body marked with numerous small black tubercles. In the course of its development, the caterpillar usually passes through six stages but sometimes may pupate after the fifth stage. In the spring the caterpillars reach maturity in about a month ; in the summer, in from eleven days to three weeks, and in late fall, the larval period is again lengthened with the decreasing temperature. The corn ear-worm belongs to the same family as the cutworms and resembles them in general appearance. The full-grown caterpillar (Fig. 135) is 1-^ to 2 inches in length, varying from light green to brown. The coloration is highly variable but the caterpillar is usually marked with longitudinal stripes, the most distinct one being a pale stigmatal stripe edged above with blackish. There is a dark stripe along the 214 MANUAL OF VEGETABLE-GARDEN INSECTS middle of the back divided by a narrow white line. The corn ear-worm might be mistaken for an army-worm of the summer brood, which it somewhat resembles, but may be distinguished by the granulose skin which under the microscope appears as if studded with minute hob-nails. When mature, the caterpillar leaves its food plant, descends to the ground and burrows into the soil in a slanting direction to a depth of two to seven inches, leaving the passage filled with loose earth. It then constructs a tunnel almost to the surface of the ground for the emergence of the moth. This tunnel is lined with compacted soil and a thin layer of silk. After completing the exit tunnel, the larva retreats to the en- larged lower part of the burrow and there transforms to a pupa. The pupa is smooth, brownish, f to nearly 1 inch in length and usually rests in a slanting posi- tion with the head upward. Pupae formed by the summer broods are usually found nearer the surface than those which winter over. The period passed in the pupal stage varies with the season. In the summer it is about two weeks and in the fall three weeks or more. The number of generations produced annually varies with the length of the season. Throughout the cotton belt there are probably four generations and sometimes a few moths of a fifth brood may emerge. In southern Texas and Florida seven generations may develop. In New Jersey and in other northern localities where the insect is a serious corn pest, only two or three generations occur. Farther north there is probably only one brood. After the first generation, the later ones become badly mixed, owing to the overlapping of broods caused by the irregular emergence of the moths, and the unequal Fig. 135. — The corn ear-worm, dorsal view (natural size). CORN INSECTS 215 development of individuals. The later generations are only partial, owing to the fact that some of the pupae of these broods do not transform until the following spring. As a rule, tomatoes are most seriously injured by the corn ear-worm early in the season. At this time corn is not large enough to be attractive to the moths and they are forced to lay their eggs on tomato. The young larvse feed slightly on the leaves and may sometimes even burrow into the stem of the j)lant, killing it down to the point reached by the larva. The injury, however, is greatest to the fruit. The caterpillars bore into tomatoes of all sizes. A caterpillar does not, as a rule, remain long in one fruit but as soon as decay sets in leaves it, often entering several fruits in succession. It is not unusual in the South for half or more of the crop to be destroyed in this way. In New Jersey the injury is confined mostly to the early crop, but in Florida the attack may continue throughout the season. Peas and beans are often attacked by the corn ear-worm when corn is not available. The caterpillars bore into the pods and devour the seeds and may sometimes tunnel in the stems as well as feed to some extent on the foliage. Cucumber, squash, melons and pumpkin are sometimes injured, the larvae boring in the stems, and even entering the fruit. Corn may be attacked while still quite small. The eggs are deposited on the leaves and the caterpillars eat out irregular holes, especially in the tuft at the center of the plant. The moths begin depositing eggs in the silk as soon as it appears. On hatching, the young caterpillar usually devom"s its egg-shell and then works its way through the silk and in about twenty minutes reaches the tip of the ear, having fed very little if at all during this time. It then begins feeding on the silk and after a time burrows down under the husk, continuing to feed on silk and the unripe kernels (Fig. 136). The injury may extend halfway down the ear. The injured kernels and the 216 MANUAL OF VEGETABLE-GARDEN INSECTS excrement left by the larva in its burrow under the husk serve as an excellent medium for the growth of various molds and bacteria, which greatly augment the injury inflicted by the insect. As many as six larvse sometimes infest an ear but usually only two or three are present, in spite of the fact that normally a much larger number of eggs are deposited on each mass of silk. This is to be accounted for by the can- nibalistic habits of the caterpillars. They feed voraciously not only on each other but on any other caterpillars that come in their way. Both field and sweet corn are subject to attack but the latter seems to be pre- ferred by the insect. The loss to field corn is not so great because the uninjured kernels can be used, but in the case of sweet corn good prices cannot be obtained for wormy ears. The pest is most destructive in the latter part of the season, owmg to the greater number of moths in the later broods. In the last crop of corn in the vicinity of New York, some- times nearly every ear is infested, while the earlier plantings may be practically free. In many parts of the South, it is mipossible to raise a clean crop of sweet corn because of the depredations of this insect. When full-grown, the cater- pillar leaves the ear, usually by gnawing a round hole through the husk, but in some cases it may escape at the tip. Some- FiG. 136. — Two full-grown ear-worms on the tip of an ear of field corn (natural size). CORN INSECTS 217 times the larvte desert the ear when only partly grown and mi- grate to other ears on the same or nearby plants. In the cotton belt the later broods of caterpillars produced after corn has become hard are to be found mostly on cotton. In Iowa and Nebraska, late brood caterpillars have been found on alfalfa and clover. Control. No practical method of controlling the corn ear-worm on field corn has yet been disco\'ered. Experiments in New Jersey have shown that the injury to sweet corn may be greatly decreased by dusting the silk with a mixture of 50 per cent powdered arsenate of lead and 50 per cent finely ground sulfur. The first application should be made soon after the silk appears, followed by one or two others before the corn is ready to pick. Dust can be applied most conveniently by means of a small hand bellows carried under the arm and equipped with a piece of rubber hose abnut two feet long attached to the outlet by which the dust is directed downward into the tip of each ear. When sweet corn is grown for the cannery, early planting is advisable, but cannot be practiced when corn is grown for the market because for this purpose a succession cover- ing as long a period as possible is required. IMuch benefit may be derived from fall or winter plowing land on which an infested crop has been grown in order to destroy the pupje. As large an area as possible should be included in this treatment as the moths are capable of flying a considerable distance. The injury to tomatoes may be in part prevented by spraying the vines with arsenate of lead f paste), 4 to G pounds in 100 gallons of water, making one or two applications before the fruit is half grown. Later applications are likely to stain the fruit. Injured tomatoes should not be left in the field but should be picked along with the others, sorted in the packing- house and should then either be buried or dumped into a pond. 218 MANUAL OF VEGETABLE-GARDEN INSECTS Tomatoes can also be partially protected from the corn ear- worm by using corn as a trap crop on which, in preference to the tomatoes, the moths will lay their eggs. Two rows of corn should be planted for every ten or twenty rows of tomatoes and so timed as to come into silk when the first tomatoes are forming. It should be cut and destroyed before the cater- pillars reach maturity. References Comstock, Rept. Cotton Insects, pp. 287-315. 1879. Riley, 4th Rept. U. S. Ent. Comm., pp. 355-384. 1885. Mally, Rept. on Bollworm, Tex. Agr. Col. 1902. U. S. Farm. Bull. 191. 1904. U. S. Bur. Ent. Bull. 50. 1905. Bibliography. U. S. Farm. Bull. 290. 1907. Ky. Agr. Exp. Sta. Bull. 187. 1914. The Corn Root-Aphis Aphis maidi-rndicis Forbes Although the corn root-aphis is generally distributed through- out the United States east of the 100th meridian, it is most injurious in the corn belt and in New Jersey, Delaware and eastern Pennsylvania. In the South Atlantic states, it has proved a troublesome pest of cotton and has also been known to infest the roots of cultivated asters in Illinois. There is some doubt as to many of the wild food plants of the corn root-aphis because of confusion with a similar species, Aphis middletoni Thomas, often found on the roots of certain wild plants such as asters and Erigeron. It is, however, ^definitely recorded from smartweed, knot weed, crab-grass, purslane, dock, fo.xtail, fleabane, mustard, sorrel, plantain, pigweed, great ragweed, thorny amaranth, green amaranth, Roman wormwood, dog fennel, shepherd's purse, lamb's quarters, poverty weed, buttonweed, purplish cudweed, sneezeweed, pineweed, dwarf CORN INSECTS 219 dandelion, pepper-grass, toadflax, mild water pepper, cockle- bur, vervain, common nightshade, skullcap, Teucrium laciniatum, Leptochloa filiformis and Mentha arvensu. The corn root-aphis has been studied most carefully in Illinois. The insect passes the winter in the egg stage in the care of a little brown ant, Lasius niger americanus Emery. The ants tend the aphids in much the same way as man cares for domestic animals, being very fond of the sweetish liquid, known as honeydew, secreted by them. This aphis has become so dependent on the ants for the care of the winter eggs and for placing the young lice on the roots of their food plants that they would doubtless all perish were there no ants present to attend them. The eggs are stored in the ants' nest, where. they are protected by the workers as carefully as are the young of their own species. Sometimes in warm days in early spring, the ants carry the eggs to the upper galleries of the nest or even lay them out in the sunshine and carry them back at night. This is probably done in order to keep the eggs in good condition and to hasten their hatching. In central Illinois the eggs begin to hatch in early April, just as the smartweed, pigeon-grass and ragweed plants are coming up. The young aphids are carried by the ants and placed on the roots of these weeds. Here they are attended by the ants, whose burrows are extended to include the roots. The young aphids pass through four nymphal stages in the course of their growth and reach maturity in about nineteen days, on the average, in Illinois. As the eggs hatch over a considerable period, usually from early April to the last of May, the last nymphs hatched will find themselves surrounded by representatives of three generations. All the individuals of the first generation are wingless but in the later generations there is a varying percentage of winged forms produced. The latter occur in greatest numbers when the roots are crowded and food is scarce. The winged forms leave the roots, come to the surface and take flight, seeking new feeding grounds. 220 MANUAL OF VEGETABLE-GARDEN INSECTS Fig. 137. — Wingless vi viparous female corn root aphis (X 13). During the summer only two forms of the aphids occur, wing- less and winged viviparous females ; males and egg-laying females are not produced till October or November and constitute the last genera- tion of the season. From eleven to twenty-two generations are produced annually, each female giving birth to nearly fifty young. With the advent of cool weather, wingless egg-laying females and wingless, or rarely winged, males are produced. The small black eggs are deposited underground in the galleries of the ants where they are cared for till the following spring. The full-grown viviparous female (Fig. 137) is about ys inch in length, bluish green, dusted with a whitish waxy pulverulence. The head and transverse bands on the thorax are black. In the winged form, the head and thorax are black or dark brown and the abdomen is pale green with three distinct black spots on each side (Fig. 138). _ By the time the corn is planted and comes up, the aphids have become crowded on the roots of the weeds and many winged forms have devel- oped. At this time the weed roots have become hardened and are thus less favorable for the develop- ment of the lice. The ants transfer many of the wingless Fig. 138. Winged viviparous female corn-root aphis (X 16). CORN INSECTS 221 aphids from the weeds to the corn roots and also seize any of the winged migrating forms that come their way and carry them down to the roots. In this way the corn soon becomes badly infested. The injury is ordinarily first noticed in irregular patches usually on the lower ground. The loss of sap caused by the feeding of the aphids lessens the vitality of the plant, causing the leaves to turn yellowish or reddish. The aphis is most destructive in years of drought because under such condi- tions the plants are least able to bear the loss of sap. Corn plants badly stinited by the root-aphis often fail to bear ears or produce only nubbins. Control. Experiments and the experience of practical corn-growers in Illinois have shown that the losses caused by the corn root- aphis may be in large measure prevented by plowing land intended for corn to a depth of six or seven inches early in the spring followed by thorough and repeated disking to break up the ants' nests and scatter the eggs of the aphis. This treat- ment also destroys the weeds on which the root-lice get their start. It also puts the soil in good tilth, making possible a strong and rapid growth of the corn. Corn is most likely to be injured by the root-aphis when the crop is grown on the same land for two successive years. INIuch injury may, therefore, be avoided by adopting a rotation in which corn does not follow corn. As a supplementary treatment, S. A. Forbes recommends the use of oil of tansy applied to each hill as a deterrent for the ants. One fourth pound of oil of tansy and 1 gallon of wood or denatured alcohol is mixed with 100 pounds of bone-meal. This is enough for an acre and should be applied with a fertilizer dropper attached to the planter. Careful preparation of the soil and thorough culti- vation will tend to make the plants able to outgrow injury by root-lice. 222 MANUAL OF VEGETABLE-GARDEN INSECTS References Forbes, 14th Kept. State Ent. 111., pp. 23-33. 1885. Forbes, ISth Rept. State Ent. 111., pp. 58-85. 1894. 111. Agr. Exp. Sta. Bull. 44, pp. 237-256. 1896. 111. Agr. Exp. Sta. Bull. 104, pp. 102-123. 1905, 111. Agr. Exp. Sta. Bull. 130. 1908. 111. Agr. Exp. Sta. Bull. 131. 1908. U. S. Bur. Ent.' Tech. Bull. 12, pp. 123-144. 1909. Bibliogravhy. U. S. Bur. Ent. Bull. 85, pp. 97-118. 1910. 111. Agr. Exp. Sta. Circ. Jan. 9, 1913. The Southern Corn Root-Worm Diabrotica duodecimpunctata Fabricius The southern corn root-worm is also known as the twelve- spotted cucumber beetle and in the South as the corn bud-worm from the habit of the larvae of kill- ing the bud or central leaves of the young corn plant. The beetle is generally distributed through- out the United States and southern Canada east of the Rocky Moun- tains southward to Florida and Mexico. It is injurious to corn from southern Illinois to Virginia and southward. The beetle (Fig. 139) is about ^ inch in length, with the head black and the thorax and wing- covers yellowish green. Each wing-cover is marked with six black spots arranged in three transverse rows. The antennae and legs are black ; the first three joints of the antennse and basal half of the femora are pale. The beetles hibernate under any convenient shelter, often in alfalfa fields. In the Fig. 139. — The southern corn root- worm beetle ( X 5) . CORN INSECTS 223 South they are dormant only for a few days at a time during periods of cold weather, and in southern Florida and Texas the beetles are active throughout the winter. The adults feed on a great variety of plants both wild and cultivated. They are often found in the blossoms of squash, pumpkin, melon and cucumber, feeding on the pollen. They also attack seedling cucurbits in much the same way as .the striped cucumber beetle and often gnaw holes in the fruit. They sometimes seriously injure young beans, peas, cabbage, cauli- flower, kale, turnip, mustard, rhubarb, asparagus, eggplant, potato, tomato and beet and there is a record of their being destructive to spinach in New Mexico. The beetles are often found in the spring feeding on the blossoms of fruit-trees and later in the season on the flowers of cotton and on the silk of corn, but they are probably most abundant on the flowers of various wild plants such as goldenrod, wild sunflower and many others. The larvje are found most abundant on the roots of corn but they also attack the roots of bean, rye, wheat, millet, alfalfa, southern chess, barnyard-grass, Johnson-grass, golden glow, Jamestown weed and pigweed (Amaranthus). The beetle deposits her eggs in early spring in cracks and crevices of the ground around the base of the plant. A single female has been known to lay over 500 eggs, but the average is probably much less. Only a few days are required for the beetle to lay her full complement of eggs, but as all the beetles do not mature at the same time, egg-laying will continue over a period of a month or more. The egg is dull yellow, oval and about tV inch in length. The eggs hatch in a week to over three weeks and the young larva begins feeding on the roots. In the case of young corn plants, the grubs often enter the stalk near the upper circle of roots, killing the bud or inner leaves, or they may eat out irregular holes in the root, often severing them from the plant. The injury is usually most severe to corn growing in low wet land. The larva becomes mature in fifteen 224 MANUAL OF VEGETABLE-GARDEN INSECTS to thirty-five days. It is then a slender grub, about i inch in length, whitish or yellowish in color with the head and cervical shield brownish. When full-grown, the lar\'a leaves the plant and constructs a small earthen cell within which it transforms to a small whitish pupa, the beetles emerging in one to two weeks. Throughout the greater part of the insect's range, there are two generations annually. In the extreme South where the beetles are active during the entire year, an additional generation may develop. The larvae of the second generation are not so injurious to corn as those of the first but they some- times injure the roots so that the plants are easily blown over by storms and in some cases ripening is delayed and the size and quality of the crop reduced. In the southwest, a variety of the southern corn root -worm has received the name of tenella Leconte. In this form the spots on the wing-covers are greatly reduced in size and the posterior ones may be entirely lacking. Control. Injury to corn by this insect may be in large measure pre- vented by planting late, after the beetles have deposited most of their eggs. Corn planted the first of May in Alabama will usually escape injury. Farther north the corresponding date would be somcAvhat later. In the case of sweet corn when it is desirable to plant the crop early, it is often possible to get a good stand in spite of the root-worms by planting an excess of seed. A rotation of crops has not proved of much value in preventing injury because the beetles are good fliers and readily find their way to corn fields for egg-laying. Since the injury to corn is usually most severe on low wet land, tile drainage is often the most practical method of solving the problem. When attacking cucumbers, squashes and melons, the beetles may be controlled by the measures suggested for the striped cucumber beetle on page 111. CORN INSECTS 225 References Garman, Psyche, 6, pp. 28-30; 44-49. 1891. Ky. Agr. Exp. Sta. Kept, for 1890, pp. 9-22. 1894. Quaintance, U. S. Div. Ent. Bull. 26, pp. 35-41. 1900. U. S. Bur. Ent. Circ. 59. 1905. Ala. Agr. Exp. Sta. Circ. 8. 1911. S. C. Agr. Exp. Sta. Bull. 161. 1912. U. S. Dept. Agr. Bull. 5. 1913. The Western Corn Root-Worm Diabrotica longicornis Say The western corn root-worm is also known as the northern corn root-worm, neither name being especially appropriate ; the former because there is no eastern corn root-worm and the latter because the species also occurs in the South. Although the insect ranges from Nova Scotia to Dakota and southward to Alabama and Mexico, it has been noticeably destructive to corn only in the specialized corn-growing region from Ohio to Nebraska and Kansas. The winter is passed in the egg stage in the ground, usually in fields in which corn grew the preceding year. The egg is about ^V inch in length, oval and dirty white in color. The eggs are deposited by the beetles in late summer or fall in the ground within a few inches of the corn plant. The female burrows into the soil for oviposition and deposits her eggs in loose groups from three or four to eight or ten. The eggs hatch in the spring over a considerable period and the larvae soon find their way to the roots of the young corn plants in case the field is again planted to this crop. They feed on the smaller roots and tunnel out the larger ones, making a slightly sinuate burrow on the side of the root just below the surface. Many of the roots are killed in this way and by the decay that often accompanies the injury. After destroying one rot)t, the grub often attacks a second but as a rule does not burrow into Q 226 MANUAL OF VEGETABLE-GARDEN INSECTS the crown. As far as known, corn is the only food plant of the larvae, but it is probable that they also feed on the roots of broom corn and sorghum. The injury to the roots inflicted by the grubs, if severe, may cause the plants to remain dwarfed and sickly or may merely weaken them so that few or imperfect ears are produced. When many of the roots have been destroyed, the corn is likely to be blown over by the wind. The larvae mature from late June to late August. They are then elongate, slender, whitish grubs with the head, cervical shield and anal plate yellow- ish brown and are about f inch in length. When full-grown, the larva leaves the root and transforms within a small earthen cell to a whitish pupa. The beetles of the new brood emerge over a long period, from about the first of July until September. They are about ^ inch in length and grass-green in color with the antennae brownish, paler towards the base (Fig. 140) . In Illinois the eggs are mostly laid between the first of August and the early part of October. There is only one generation annually. The beetles feed on the pollen and silk of corn and are often found on the blossoms of buckwheat, goldenrod, smartweed, thistle and many other wild plants as well as in the flowers of cucurbits. They some- times gnaw into the unripe kernels of corn where the husk has been broken and have been known to gnaw holes in the rind of pumpkin and squash and to feed on the leaves of radish and turnip. Fig. 140. — The western corn root-worm beetle (X 8). CORN INSECTS 227 Control. Owing to the eggs of the western corn root-worm being deposited only in corn fields, injury may be avoided by not planting land to corn for more than two years in succession. References Forbes, 12th Kept. TU. State Ent. for 1882, pp. 10-31. U. S. Dept. Agr. Bull. 8. 1913. The Colorado Corn Root-Worm Dinhroticn virgifera Leconte In Colorado, sweet corn is sometimes seriously injured by a larva similar to that of the southern corn root-worm that burrows into the stalk below ground. The female beetle is ^ inch in length and closely resembles the striped cucumber beetle in general appearance, but in the male the wing-cover is black except for a narrow yellow margin and a yellow spot near the tip. The beetles are often troublesome in vegetable-gardens where they feed on a variety of plants. The eggs are pale yellow and about ^V i"<^'h in length. They are laid in the fall in the ground near the corn plants and do not hatch till the following spring. The larva is a little less than | inch in length, pale yellow, with the head and anal plate black. The insect is apparently single brooded in Colorado. Injury by this species may be prevented in large measure by not growing corn for successive years on the same land. Reference Gillette, Jour. Econ. Ent., 5, pp. 364-366. 1912. 228 MANUAL OF VEGETABLE-GARDEN INSECTS The Larger Corn Stalk-Borer Diatrcea zeacolella Dyar In the southern states northward to Kansas and Maryland, corn is sometimes attacked by a whitish caterpillar marked with dark brown spots. This insect is closely related to the sugar- cane borer and until recently the two have been considered the same. These caterpillars bore into the stalks of young corn, causing the plants to become dwarfed and distorted. They often bore through the unopened leaves, producing groups of small holes symmetrically arranged on the two halves of the expanded leaf. The larvse of the second generation burrow into the stalks below the second or third joint, weakening them so that the plants are easily blown over by the wind. The insect hibernates as a full-grown larva in a burrow in the tap-root below the surface of the ground. Pupation takes place in the spring within the burrow and the moths emerge in ten days or more. The straw-yellow moth, with an expanse of 1 to 1| inches, lays her eggs in clusters of two to twenty-five, either on the lower or more rarely on the upper side of the leaves of the young corn. The egg when first laid is creamy white, gradually changing to orange-brown, flattened, oval, slightly convex and about -^ inch in length. In the cluster the eggs overlap and are usually arranged in two, three or four rows. The egg hatches in a week to ten days and the young caterpillars at first feed on the upper leafy part of the young plant but soon bore down into the stalk. There is considerable migration of the caterpillars from plant to plant and a borer may leave the stalk at one place only to re-enter at another point. The caterpillars mature in twenty to thirty days. The full-grown larva is about an inch in length, dirty white, usually marked with numerous dark brown spots. When about to pupate, the caterpillar cuts through the stalk an exit hole for the moth CORN INSECTS 229 which is covered with silk and the burrow is plugged below with a mass of frass. The shining brown pupa is nearly an inch in length. The mt)ths of the second brood emerge in six to ten days and lay eggs for another brood of larvae. These borers riddle the stalks near the base with numerous burrows and when mature descend to near the surface of the ground, where they usually remain in the larval condition till the following spring. These hibernating larvai are nearly pure white, the brown spots having disappeared. There are apparently only two generations annually. Control. Tlie most practical measure so far suggested for the control of this insect is the adoption of a proper system of crop rotation. In this system corn should not follow corn. When it is necessary to plant corn after corn, the stalks and stubble should be raked up and burned before the moths emerge in the spring. References Comstoek, U. S. Ent. Rept. for 1880, pp. 243-245. 1881. Howard, Insect Life, IV, pp. 95-103. 1891. U. S. Farm. Bull. 634. 1914. Holloway, Jour. Agr. Research, VI, pp. 621-625. 1916. The Lesser Corn Stalk-Borer Elasmopalpus lignosellus Zeller In the southern states, corn, sugar-cane, cowpea, bean and peanut are sometimes attacked by a small greenish, brown- striped caterpillar that burrows in the stalk at or just below the surface of the ground. It is most injurious on thin sandy or gravelly land. The insect has also been recorded as infesting crab-grass and Johnson-grass. It ranges from Maine along the coast to Pennsylvania westward to Iowa, Texas and southern California and southward to Patagonia. 230 MANUAL OF VEGETABLE-GARDEN INSECTS Hibernation takes place in three stages : larva, pupa and adult. In South Carolina the insect usually enters the winter in the larval state but may transform to a pupa before spring. The egg is greenish white to reddish, ovate, about 3V inch in length. The time and method of depositing the eggs in the field have not been recorded. The eggs hatch in about three days in the summer and in five days to a week in the fall. The caterpillars burrow into the young corn plant near the surface of the ground and kill the central tuft of leaves, often causing the plant to die or leaving it in a dwarfed, deformed condition, incapable of bearing a crop. The larva becomes mature in two or three weeks, depending on the season. In the late fall it may require nearly six weeks to reach maturity. In the course of its growth, the larva molts from four to six times. When full-grown, it is about f inch in length, greenish in color, whitish above and the body is marked with nine narrow longi- tudinal brownish stripes and crossed by a broad brown band on the posterior margin of each segment. The head and cervical shield are shining dark brown, with a pale line running over the top of the head and crossing the shield. The larvte do not remain in their burrows in the plant except when feeding but are usually found in a thin silken tube, in which bits of excrement and grains of sand are incorporated, attached to the side of the plant just below the surface of the ground. In feeding on the older corn plants, they not only burrow into the stalk but also girdle the plant, causing it to break over easily. Several larvaj may infest a single plant. When mature they construct oval silken cocoons covered with particles of sand and dirt in which they transform to brownish pupae about ^ inch in length. The moths emerge in one to three weeks, depending on the tempera- ture. The moth has an expanse of f to 1 inch. In the male the front wings are light brownish yellow, usually dark gray on the margins with two or three small dark spots on the disk. The hind wings are whitish, edged with light brown. In the CORN INSECTS 231 female the front wings are darker, sometimes nearly black but forms occur in which they are reddish. The moths are inacti\'e, feign death when disturbed, and fall to the ground with wings and antennjTe drawn closely to the body. Their flight is swift but of short duration. There are apparently four generations annually in South Carolina. The injury caused by the lesser corn stalk-borer may be prevented in part by clearing the field of crop remnants in the fall and by plowing the land in late fall or early winter to destroy the insects in their winter quarters. In some cases early planting will cause the crop to escape serious infestation. References Riley. TJ. S. Ent. Rept. for ISSl and 1S,S2, pp. 142-145. U. S. Div. Ent. Bull. 23. pp. 17-22. 1900. U. S. Dept. Agr. Bull. 539. 1917. The Brown Fruit-Chafer . Enphorin inda Linnaeus The ears of sweet corn are sometimes injured in the fall by a thick-set, yellowish brown beetle \ inch or more in length. Its wing-covers are sprinkled all over with small, irregular black dots. These beetles appear in late summer or early fall and feed on the pollen of flowers, ripe fruit and corn in the milk. They attack the tip of the ear, working down under the husk and devouring the unripe kernels. After feeding for some time, they go into hibernation and very early the next spring may be seen flying close to the ground with a loud buzzing sound. The female deposits her white, nearly spherical eggs in the vicinity of manure heaps, in piles of rotting sod and other decaying vegetable matter. When full-grown the larva is some- what over an inch in length, strongly curved and dirty white in color ; the posterior part of the body has a dull leaden hue 232 MANUAL OF VEGETABLE-GARDEN INSECTS from the contents of the alimentary canal. It differs from the white grub (Lachnosterna) in its shorter and more robust form, in the shorter legs and smaller head, and in its habit of crawling on its back. In July the larvre pupate within earthen cocoons of a somewhat angular external form. The beetles emerge during August and September. There is only one generation a year. Hand-picking of the beetles is apparently the most practicable means of controlling this insect when it is found working on sweet corn. Stink-Bugs Two species of stink-bugs, Euschistus mriolarms Palisot de Beauvais and E. euschistoides Snellen van Vollenhoven, some- times injure sweet corn by puncturing the kernels through the husk. They suck out the juice, causing the kernels to become sunken or to pop open. The kernels become infected with mold These stink-bugs are about ^ length, dull grayish brown, sometimes tinged with reddish or greenish and dotted with numer- ous black punctures. In E. Dariolarius (Fig. 141) the sides of the pro- thorax are acutely pointed, while in E. euschistoides (Fig. 142) they are rounded. In the male of the former, there is a dis- tinct black spot on the underside of the last abdominal segment. The first mentioned of these bugs has also been recorded as injuring tobacco, raspberries, peaches and strawberries. It has injured inch in Fig. 141. — Euschis- tus variolar ius, adult (X2). Fig. 142. — Euschistus euschistoides, adult (X2). CORN INSECTS 233 been known to puncture ripening tomatoes and the stems of melon, asparagus and the pods of okra. The adults are to be found throughout the summer and the insect is said to hiber- nate in this stage. The life history of each species has not been fully recorded. These stink-bugs are most abundant on corn and tomatoes raised in the vicinity of waste land grown up to rank weeds. Other Corn Insects Cabbage wobworni : 1(5 Seed-corn inajj:got : 3(j Green soldier-bug : 42 False chinch-bug : 47 Yellow bear caterpillar : 3.57 Carrot beetle : 185 Negro-bug : 196 Western twelve-spotted cucumber beetle: 114 Belted cucumber beetle : 115 Common stalk-borer : 157 Burdock borer : 160 Bean leaf-beetle : 65 Garden flea-hopper : 77 Spotted cutworm : 262 Well-marked cutworm : 263 Greasy cutworm : 265 Dark-sided cutworm : 268 Striped cutworm : 270 Dingy cutworm : 271 Granulated cutworm : 273 Clay-backed cutworm : 274 Variegated cutworm : 276 Glassy cutworm : 279 Yellow-headed cutworm : 281 Spotted-legged cutworm : 282 Bristly cutworm : 285 Bronzed cutworm : 286 Army cutworm : 287 Fall army-worm : 292 Beet army-worm : 294 Yellow-striped army-worm : 295 Black blister-beetle : 307 234 MANUAL OF VEGETABLE-GARDEN INSECTS Potato flea-beetle : 314 Pale-striped flea-beetle : 321 Smartweed flea-beetle : 323 Western cabbage flea-beetle : 327 Desert corn flea-beetle : 334 Millipedes: 342 Slugs: 354 Wheat wireworm : 348 Sugar-beet wireworm : 349 Corn and cotton wireworm : 349 CHAPTER XII SWEET POTATO INSECTS The sweet potato in the United States is not, as a rule, subject to serious injury by insects, except in limited areas where the weevil has become established. When the plants are just set out, they are likely to be attacked by flea-beetles (see page 332) and by tortoise beetles. In Florida the late crop is often seriously injured by the sweet potato white-fly. The Tortoise Beetles Sweet potato vines are subject to injury soon after trans- planting by several species of tortoise beetles that eat out more or less circular holes in the leaves. These leaf-beetles are flattened below and convex above and have the margins of the prothorax and wing-covers broadly expanded and more or less semi-transparent, giving the insect a regularly oval outline. The head is concealed under the expanded margin of the prothorax. The beetles have a striking resemblance in form to miniature turtles — hence their common name. The larvae are sometimes known as peddlers from their habit of carrying their cast skins and excrement in a pack over the back supported on two long spines arising at the posterior end of the body. Along the edge of the body is a row of rather large branched spines. In New Jersey, the beetles appear on the sweet potato plants as soon as they are transplanted in late May or early June and, after feeding for a time, lay eggs from which a new brood 235 236 MANUAL OF VEGETABLE-GARDEN INSECTS of beetles is produced in July. The new beetles feed for a short time and then go into hibernation. There is only one generation a year, at least in the northern states. The striped tortoise beetle, Cassida bivittata Say This is the commonest and most injurious species attacking sweet potatoes in New Jersey and is widely distributed through- out the regions in which this crop is grown in the eastern United States. The beetle (Fig. 143) is about -^ inch in length ; the prothorax is reddish with the margin yellowish ; the wing-covers are dull yellow marked with five longitudinal black stripes ; the underside of the body and the legs are dark brown or black. The beetles appear in the field in early spring and feed for a time on wild morning-glory and attack the sweet potato plants as soon as they are set Fig 143 — The ^^^ ^" ^^^ field. The eggs are glued to the under- striped tor- side of the leaves singly and hatch in a few days. ( x^5) ^^^^^^ The larva is yellowish white with a grayish longi- tudinal line along the middle of the back. This larva differs from the other species infesting the sweet potato in not mixing excrement with the cast skins carried on the anal fork. This appendage is not carried close to the back but is usually elevated at an angle of about 45 degrees. When full-grown, the larva attaches itself to the leaf by the tip of its body and, after resting for two days, the larval skin splits along the back and is pushed back towards the hind end of the body where it is retained surrounding the point of attachment. When fully colored, the pupa is dull brownish and may be distinguished from the other species by the elongate whitish mass of cast skins on the anal fork which still adheres to the insect. The beetles emerge in July and after feeding a short time on the leaves of sweet potato and wild morning-glory go into hiber- nation early. SWEET POTATO INSECTS 237 The black-kgged tortoise beetle, Cassida nigripes 01i\'ier This beetle (Fig. 144) is a little over i inch in length. When at rest in the sunshine, it is of a beautiful golden tint but loses its brilliancy when disturbed and after death fades to a yel- lowish brown. Each wing-cover is marked with three black spots arranged in a triangle. The legs and the tip of the antennse are black. The eggs are laid in rows of three to twelve on the stems of the plant. The laryse are bright straw-yellow with a curved black mark on each side of the prothorax. The spines along the side of the body are tipped with black. The anal fork is carried close to the back and the excrement is arranged in a characteristic yig. 144. — Thehiack- manner with long shreds extending out side- lagged tortoise beetle wise. The pupa is dark brown with the lateral spines transparent white. The larvse reach maturity in about two weeks and the pupal period is nearly as long. TIic golden tortoise beetle, Coptocycla bicolor Fabricius When basking in the sunshine, this beetle has been likened to a drop of molten gold ; the coloration becomes duller, how- ever, when the insect is disturbed or in cloudy weather and after death fades to a light reddish brown. The scientific name, bicolor, was apparently given because of the contrast between the golden central part of the body and the thin semi-trans- parent margin. The beetle (Fig. 145) is a little over ^ inch in length. The eggs are glued singly to the underside of the leaf. The egg is about ^ inch in length, dirty white in color, rounded below, ridged on the sides above and is usually armed at one end with three sharp diverging spines. The Fig. 145. — The golden tortoise beetle (X o). 238 MANUAL OF VEGETABLE-GARDEN INSECTS larva is dark brown in color, lighter on the back and is com- pletely covered by the large mass of excrement carried on the anal fork. The larva becomes mature in about eighteen days and transforms to a brown pupa with three dark stripes on the transparent prothorax. The covering of excrement is retained during the pupal period, which lasts a week to eleven days. In addition to sweet potato and wild morning-glory, this in- sect occasionally feeds on bittersweet. The mottled tortoise beetle, Coptocycla signifera Herbst This beetle (Fig. 146), which is about ^ inch in length, is readily distinguished from the others feeding on sweet potato by having the disk and the front margin of the wing- covers black, mottled with gold or yellow. The disk of the prothorax is black and contains two yellow spots. The larva is green in color, bluish along the back. The excrement is arranged on the anal fork „ ,.„ „, ^ in broad masses, sometimes with shreds Fig. 146. — The mot- . ' tied tortoise beetle extending from the sides. The larva be- ^'^'*^' comes mature in about sixteen days and transforms on the leaf to a green pupa marked with a con- spicuous black ring around the first abdominal spiracle. This species is not confined to sweet potato and wild morning-glory but also attacks buckeye and thorn. The argus tortoise beetle, Chelymorpha argus Herbst This species has been reported as occasionally attacking the sweet potato. It is ^^ to t^ inch in length and varies in color from brick-red to clay-yellow. The wing-covers are marked with thirteen black spots and the prothorax usually with six, arranged in two rows. It has also been reported as feeding on milkweed, sunflower, wild morning-glory and horse-radish. SWEET POTATO INSECTS 239 Control. Tortoise beetles are readily killed by spraying the vines with arsenate of lead (paste), 2 pounds in 50 gallons of water, taking care to spray the mixture on the underside of the leaves. The young plants may also be protected from injury by dipping them in a mixture of arsenate of lead and water as recommended for the control of the sweet potato flea-beetle on page 333. Reference Walsh and Riley, Am. Ent., 1, pp. 234-238. 18G9. The Sweet Potato Weevil Cylas formicarius Fabrieius This highly destructive pest of the sweet potato is a native of the tropics. It was first seen in the southern United States in 1875 and now occurs from Georgia and Florida westward along the Gulf of Mexico into Texas. The insect is also found in India, Australia, Cochin China, Java, Madagascar and the West Indies. The adult is a slender snout-beetle about ^ inch in length (Fig. 147). The head is dusky black ; the prothorax and legs are reddish and the wing-covers a metallic bluish black. The prothorax is strongly con- stricted near the hind margin ; the snout is stout and is carried projecting forward. The beetles are decidedly ant-like both in form and coloration. While they possess functional wings, they rarely use them, but are sometimes attracted to lights. The beetle deposits her creamy white, elongate oval eggs, about 3^ inch in length, singly in a small hollow eaten out in the stem or in a tuber that has become exposed. The eggs hatch in four to six days. The larvie hatching in the stems Fig. 147. — The sweet potato weevil (X 4|). 240 MANUAL OF VEGETABLE-GARDEN INSECTS burrow downward through the center to the tuber. On reach- ing the potato, its burrow becomes somewhat hirger and winds aimlessly through the flesh. The full-grown larva is about Ys inch in length, the body is white and the head yellowish or brownish. The grubs become mature in two to three weeks. The tissue surrounding the burrow becomes discolored and decay sets in, giving the tuber a peculiar odor. When mature the grub eats out an oval cavity and after resting a day or two transforms into a white pupa about ^ to ^ inch in length. The pupal period occupies five to eight days, and after waiting two or three days to harden, the beetle eats its way out of the pupal cell. The beetles may then either leave the potato or may deposit eggs for another brood in the same tuber. Several hundred larvje may occupy the same potato and breeding may continue until all food material has been destroyed. Gen- eration after generation follow each other as long as food is available, but the beetles are able to exist for a long period without eating and resume reproductive activity when food is again available. The life cycle is completed, under favorable conditions, in about a month. The beetles are rather general feeders and are often found feeding on species of wild morning- glory and it is believed they can breed in these plants. The sweet potato weevil is a most destructive pest and has caused the abandonment of the growing of sweet potatoes in many localities. It is especially injurious to the potatoes in storage pits, where breeding may continue until the tubers are entirely consumed. Control. Under conditions obtaining in the southern states, the in- juries inflicted by this weevil may be prevented in large measure by not planting sweet potatoes on or near infested fields. In some localities it would pay to abandon the crop over a large area for two or three years in order to starve out the weevils. I SWEET POTATO INSECTS 241 Infested tubers sliould not be left in the field. Those only slightly injured may be fed to stoek but those more badly in- fested should be burned or buried deeply. Care should be taken not to introduce the wee\'il into uninfested localities by means of infested tubers used for seed. References Tryon, Queensland Agr. Jour., 7, pp. 17G-189. 1900. Tex. Agr. Exp. Sta. Bull. 93. Maxwell-Lefroy, Mem. Dept. Agr. India, Ent. Series, 2, pp. 155-159. 1910. The Sweet Potato Leaf-Roller Pilocrocis tripunctata Fabrieius A leaf-roller has been reported as occasionally injurious to sweet potatoes in southern Texas. It is a native of the West Indies and occurs sparingly in Louisiana and Florida. The larva^ are bluish green in color with the head pale yellow, and when mature are almost an inch in length. The caterpillars feed on the foliage and fold the leaves, thus making a retreat within which the larva lives and within which it spins its cocoon. The pupa is dark brown and about f inch in length. The moth has an expanse of about an inch and is light yellow in color. The front and outer edge of the front wdngs are grayish brown. There is a nearly straight brown line across the base of the front wing and a wavy line of the same color three quarters the distance from the base on both wings. There are two black spots near the front margin of the front wing and one on the hind wing. There are several generations annually, about twenty-five days being required for the completion of the life cycle. This sweet potato pest may be controlled by spraying the vines with arsenate of lead (paste), 4 pounds in 50 gallons of water. ^ Reference U. S. Dept. Agr. Bull. G09. 1917. 242 MANUAL OF VEGETABLE-GARDEN INSECTS The Sweet Potato White-Fly Bemisia inconspicun Quaintance' In southern Florida sweet potatoes, especially the late crop, are often subject to very serious injury by this species of white- fly, which in general appearance is similar to the common green- house white-fly. The eggs are deposited on the underside of the leaves and hatch in about a week. The nymphs are often abundant enough nearly to cover the entire under surface of the leaf, sucking out the sap and sometimes killing the plant. This white-fly may be controlled by one or two applications of soap solution or kerosene emulsion applied to the underside of the leaves. Other Sweet Potato Insects Garden web worm : 18 Nezara viridula : 43 Yellow bear caterpillar : 357 Carrot beetle : 185 Potato aphis : 150 Garden flea-hopper : 77 Dark-sided cutworm : 268 Striped cutworm : 270 Dingy cutworm : 271 Clay-backed cutworm : 274 Variegated cutworm : 276 Army-worm : 288 Fall army-worm : 292 Ash-gray blister-beetle : 306 Pale-striped flea-beetle : 321 Sweet potato flea-beetle : 332 Root-knot nematode : 338 Corn and cotton wireworm : 349 CHAPTER XIII ONION INSECTS Onions are subject to attack by a relatively small number of insects. The most important of these are the onion maggot and the onion thrips, but occasionally cutworms and wire- worms may cause serious loss. The Onion Maggot Phorbia ceparum Meigen In Europe and America, onions are often severely injured by the attacks of a small white maggot that feeds on the under- ground stem or in the bulb. The maggots may attack and destroy the plants soon after the seeds have germinated, and the failure to obtain a stand is, therefore, often attributed to poor seed. The flies appear in the onion fields in the spring and the female deposits her smooth, white, elongate oval eggs, which are slightly grooved on one side and about -it inch in length, in the base of the leaf-sheath, on the side of the stem near the ground, and in cracks and crevices of the soil. The eggs hatch in three to ten days and the young maggot works its way down along the stem, usually within the sheath. If the plant is very young, the maggot may so injure the stem that the whole top dies. When the plants are older, the maggots bur- row into the bulb and cause decay to develop. Several maggots are often found in a single bulb. The full-grown maggot is nearly I inch in length, smooth, and dull whitish in color. The 243 244 MANUAL OF VEGETABLE-GARDEN INSECTS maggot is largest at the hind end of the body and tapers to a point at the head. Posteriorly the body is obliquely truncate. The flat surface is surrounded by a row of twelve fleshy tubercles, of which the middle lower pair are single-pointed and not two- toothed as in the case of the cabbage root-maggot. In the onion maggot, in addition to the two tubercles just back of the vent, there are two smaller ones on the ventral side just in front of the two large ventral marginal tubercles ; they aid the larva in crawling. The maggots become full-grown in two to three weeks in green onions. In second-year onions, they develop more slowly and sometimes require four or five weeks to reach maturity. When full-grown, they transform to pupse within the hardened larval skin or puparium, generally in the ground surrounding the plant; sometimes the transformation takes place within the bulb. The puparium resembles a grain of wheat in form, is of a chestnut brown color and about j inch in length. The flies closely resemble those of the cabbage and seed-corn mag- gots but the males may be separated by the characters given in Fig. 26. They emerge from the puparia in about two weeks and lay eggs for another brood. There are at least two or three broods annually. The insect hibernates principally in the form of puparia, but both maggots and flies some- times survive the winter. Control. The onion maggot has been found rather difficult to control. Carbolic acid emulsion applied as described under cabbage root-maggot, page 33, has been found of some value for killing the eggs and young maggots. Clean cultivation and rotation of crops are widely recommended to prevent maggot attack. Recent experiments in Wisconsin have shown, however, that since the flies require from ten days to two weeks after emer- gence in which to mature their eggs for deposition, the insects ONION INSECTS 245 can be more easily and satisfactorily controlled by killiniij them with a sweetened poison spray. The most satisfactory results have been obtained by using the following formula : Sodium arsenite | ounce Water 1 gallon Molasses 1 pint This material should be sprinkled over the plants and sur- rounding soil when the flies first appear so that they may be killed before laying their eggs. The application should be repeated at intervals of a week, or oftener during rainy seasons. References Cornell Agr. Exp. Sta. Bull. 78, pp. 495-496. 1894. N. J. Agr. E.xp. Sta. Bull. 200. 1907. Conn. Agr. Exp. Sta. Rept. for 1911, pp. 286-292. Severin and Severin, Jour. Ee. Ent., 8, pp. 342-350. 1915. The Onion Thrips Thrips labaci Lindeman Onions are subject to injury by- a small yellowish thrips which punctures the epidermis of the leaves, sucks out the juices and causes the plants to turn whitish, wilt and fall down. This trouble is known among onion-growers as white blast. The onion thrips is almost cosmopolitan in its distribution, occurring in Europe, North America, South Africa and Aus- tralia. In the United States it has been reported from nearly all parts of the country and is present in southern Canada. In some seasons this insect is the most serious enemy of the onion crop on the muck lands of New York, Ohio and Indiana and in the Bermuda onion regions of Texas. It sometimes seriously infests cabbage and cauliflower and is found on many wild and cultivated plants including cucumber and melon. In Europe it is a serious enemy of tobacco. 246 MANUAL OF VEGETABLE-GARDEN INSECTS Fig. 148. — The onion thrips, adult female (X 30). The onion thrips passes the winter in both the adult and nymphal state on onion plants left in the field. It is also probable that the thrips hibernates in the rubbish around the edge of the field, since the infestation usually begins along the weedy borders and gradually spreads over the remainder of the field. The adult female thrips (Fig. 148) is about -^ inch in length and varies from light yellow to brownish yellow in color. The wings are long and narrow and bear on the hind margin a fringe of long hairs. The male is rarely found and the females normally reproduce with- out being fertilized. The egg is translucent white, irregularly bean-shaped and about xio' inch in length. It is inserted nearly its full length into the tissue of the leaf; the tip of the smaller end projects slightly above the surface. The eggs hatch in five to ten days, the longer period being the more common. The newly hatched nymph is about tu inch in length and translucent white in color with the eyes bright red (Fig. 149). After feeding, the body assumes a greenish color from the ingested food. The first stage lasts about two days but in some cases the period is longer. In the second stage, the insect is about ^V inch in length and varies in color from pale yellow to lemon-yellow (Fig. 150). These second-stage nymphs complete their growth in about ten days after hatching ; they then leave the plant and Fig. 149. — The onion thrips, first stage nymph (X 75). ONION INSECTS 247 enter the ground a short distance, where, by twisting and turning their bodies, they construct small earthen cells. In these cavities the insects molt and thus enter the third nymphal, or so-called prepupal, stage. These third-stage nymphs are yellowish white in color and the wing-pads extend to the middle of the second abdominal segment. They do not feed in this stage but remain quietly resting in their earthen cells. They are able to walk, however, and when disturbed soon crawl into hiding again. In two or three days the insect molts and enters the fourth and last nymphal stage (sometimes known as the popular stage). The fourth stage is whitish in color and the wing-pads extend to the eighth abdominal segment ; the body is more spiny than in the preceding stages. In this stage, which lasts from one to six da^'s, the insect remains in a quiescent condition and takes no food. At the next molt the thrips becomes adult, returns to the plant and re- sumes feeding. The life cycle is completed in about twenty-six days. There are five or six generations annually and breeding con- tinues until stopped by cold weather. A careful examination of infested onion plants at any time during the summer will disclose the presence of four stages of the onion thrips, viz., eggs, first- and second-stage nymphs, and winged adult females. The first- and second-stage nymphs may be distinguished by the difference in size and by the more distinctly yellow coloration of the latter. Both the nymphs and adults feed on all parts of the leaves but are to be found in greatest numbers hidtlen under the sheath at the base of the leaves or between the young leaves at the center of the plant. In feeding, the thrips punctures the epidermis of the leaf with its sharp needle-like mouth-parts and then sucks out the juices Fig. 150. — The onion thrips, second stage nymph (X45). 248 MANUAL OF VEGETABLE-GARDEN INSECTS of the plant, killing the cells and causing them to turn whitish. When the infestation is severe and the punctures consequently very numerous and close together, the leaves lose their dark green color and assume a dirty white or bleached appearance. The tender leaves at the center of the plant do not turn white when punctured by the thrips, but instead curl inward and downward and present a thickened deformed appearance. Badly injured plants wilt and the leaves fall over on the ground ; in such cases, the bulbs do not make the proper growth and the crop is of small size and inferior in quality. The plants are most susceptible to injury by thrips during June and July when they should be making their most rapid growth. Thrips are most destructive in years of drought because, under unfavorable conditions, the plants are less able to outgrow the injury. Onions grown on poor soil or when poorly cultivated are more likely to be injured by thrips than when planted on good ground and well cared for. When onions are grown for seed the thrips often infest the flower- heads in sufficient numbers greatly to reduce the crop. Infested cabbage and cauliflower leaves turn brownish or rusty instead of dirty white, as in the case of onions. As a rule the injury is confined to the outer leaves, and is usually outgrown by the plants, provided other conditions are favorable. Control. Onion thrips can be killed by application of such contact insecticides as whale-oil soap, kerosene emulsion and tobacco extracts. The best results have been obtained by spraying early, before the leaves turn down, with "Black Leaf 40" tobacco extract, 1 pint in 100 gallons of water in which there have been dissolved 5 pounds of soap. There are great difficul- ties in applying the spray to large fields ; heavy traction or power sprayers cannot be employed on the soft muck soil on which onions are usually grown. The knapsack sprayer can ONION INSECTS 249 be used in the small onion patch but its use is too laborious and expensive to be practical in the large commercial onion field. To be effective, a considerable quantity of the liquid must be utilized thoroughly to wet the plants and a strong spray is needed to force the material down into the sheaths of the leaves and between the tender leaves at the center of the plant. Some better method of applying is needed in order to make spraying for the onion thrips a practical success under commercial conditions. References N. Y. (Geneva) Agr. Exp. Sta. Bull. 8.3, pp. 680-683. 1894. Ha. Agr. Exp. Sta. Bull. 46, pp. 10.3-114. 1898. J. C. Faure, Unpublished thesis, Cornell University Library. The Barred-Winged Onion Fly Chcetopsis aenea Wiedemann Onions are occasionally injured by a yellowish or whitish maggot about \ inch in length, that burrows in the bulbs, causing decay to ensue. The maggots of this insect have also been found injuring corn, wheat, oats, sorghum and sugar- cane and have been reared from the common reed. The larvae have also been recorded as parasitic on the common stalk- borer and on a lepidopterous borer in cat-tail. The insect is native to America and ranges throughout the eastern United States from Canada to the West Indies. The fly is about ts inch in length with the head grayish and the thorax and abdo- men metallic green. The wings are whitish crossed by three broad brown bands. The life history of this insect has been studied on oats. The female deposits her minute, elongate, pointed white eggs just under the edge of the leaf-sheath, singly or in groups of two to five. The maggots work down inside the leaf-sheath where, when mature, they transform into polished brown puparia about ^ inch in length. In 250 MANUAL OF VEGETABLE-GARDEN INSECTS Michigan the maggots were found to winter in the onions. There are said to be three or four broods annually. References Insect Life, 7, pp. 352-354. 1895. Mich. Agr. Exp. Sta. Bull. 200, pp. 206-208. 1902. The Black Onion Fly Tritoxa flexa Wiedemann Occasionally associated with the insect last treated are found the maggots of another fly. This species is native to America and ranges through the northern states from New Jersey to Minnesota. The fly is ts inch in length and dull black in color. The wings are dull brown marked with three oblique whitish bands. There are thought to be two broods annually. The maggots sometimes continue to work in stored onions, reduc- ing them to mere shells. No satisfactory control for this onion pest is known. Other Onion Insects Cabbage web worm : 16 Seed-corn maggot : 36 Yellow bear caterpillar : 357 Sugar-beet webworm : 97 Belted cucumber beetle : 115 Garden springtail : 139 Bean aphis : 76 Spotted cutworm : 262 Greasy cutworm : 265 Dark-sided cutworm : 268 Striped cutworm : 270 Clay-backed cutworm : 274 Black army-worm : 275 Variegated cutworm : 276 Army cutworm : 287 Beet army-worm : 294 Black blister-beetle : 307 Root-knot nematode : 338 CHAPTER XIV INSECTS INJURIOUS TO MINOR VEGETABLE CROPS The crops treated in this chapter — rhubarb, okra, salsify, pepper, water-cress and lettuce — are not, as a rule, seriously injured by insects and the control of these pests is of less im- portance in the culture of these vegetables than in the case of those previously treated. Rhubarb Rhubarb is not usually seriously affected by insects. Its most important enemies are the rhubarb curculio, the hop flea-beetle, the spinach aphis, the bean aphis and certain species of cutworms. The rhubarb curcuHo, Lixus concavus Say The leaf-stalks of rhubarb are often injured by the feeding and .egg-laying punctures of a rather large black, yellow-dusted snout-beetle. The sap exudes from the wounds and collects as glistening drops of gum. Fortunately the eggs do not hatch when deposited in rhubarb but are killed by the flow of sap. This insect ranges from New England to Idaho and southward to Florida and Louisiana. The beetle (Fig. 151) is about ^ inch in length and black in color dusted with a yellowish covering which easily rubs off. The head is provided with a curved snout on the end of which 251 252 MANUAL OF VEGETABLE-GARDEN INSECTS the mandibles are borne. The insect passes the winter usually in the adult stage hidden away in dry sheltered places. The adults appear in the spring and are often seen resting on the stems and foliage of rhubarb and dock. They feed on the edge of the leaves and puncture the stems with their beaks. The female deposits her eggs singly in cavities about i inch deep in the stalks of dock, sunflower, thistle and in the leaf-stems and flower-stalks of rhubarb. The eggs are oblong oval, yellowish white in color and about ^e hich in length. They hatch in a week or ten days when deposited in their wild food plants but, as previously stated, are not able to develop in rhubarb. On hatching the larva burrows down through the stalk so that when it reaches maturity it occu- pies a cavity just below the surface of the ground. Although many eggs are often laid in the same stem, usually only one grub reaches Fig. 151. — The rhubarb maturitv. The full-grown larva is curcuho(X2i). ' u ^ •? • -u • a rootless grub about -f incn in length and is white with a brownish head. As the eggs are laid over a considerable period from the first of June till the middle of July, the grubs do not reach maturity at the same time. The larval period occupies, on an average, eight or nine weeks. In New Jersey the greater number are mature by the middle of August. The pupa is white, about ^ inch in length, and is found in a rather large cavity in the crown of the plant just below the surface of the ground. The pupal period occupies a little over a week. After transformation the beetle remains in the pupal chamber for several days until fully hardened and then gnaws its way out and after feeding a short time goes into hibernation. There is only one generation annually. The beetles are easily seen resting on the plants and may be readily captured and destroyed by hand. All wild plants in INJURIOUS TO MINOR VEGETABLE CROPS 253 which the beetles breed should be destroyed in the vicinity of rhubarb beds or a few dock plants may be left growing as a trap in which the beetles will deposit their eggs, when they should be destroyed before the grubs reach maturity. References U. S. Div. FaiU Bull. 23, pp. 61-69. 1900. Weiss, Jour. Econ. Ent. 5, pp. 434-436. 1912. Other rhubarb insects Southern corn root-worm : 222 Yellow bear caterpillar : 357 Spinach aphis : 105 Common stalk-borer : 157 Burdock borer : 160 Bean aphis : 76 Spotted cutworm : 262 Striped cutworm : 270 Variegated cutworm : 276 Army cutworm : 287 Hop flea-beetle : 335 Okra The insect enemies of okra are not numerous. The pods are often attacked by the corn ear-worm and the buds and leaves are injured by the caterpillar of the gray hair-streak butterfly. The plants are also attacked by the spinach aphis and melon aphis and are often defoliated by the okra caterpillar. The okra caterpillar, Anomis erosa Hiibner Okra and roselle are likely to be defoliated by a green looping caterpillar related to the cotton worm. This insect also feeds on several species of hibiscus, abutilon, hollyhock and on Urena lobata and is occasionally found on cotton. It ranges throughout the southern United States, the West Indies, 254 MANUAL OF VEGETABLE-GARDEN INSECTS South Africa, Madagascar, Mauritius, the Oriental region and Austraha. The moth has an expanse of It to li inches. The front wing has the outer margin angled at the middle. The basal half is yellow usually shaded with light brown and the outer half is light pinkish brown often shaded with yellow. The hind wings are pale yellow shading into ocher yellow towards the outer border. The moth deposits her pale green, globular, slightly flattened eggs singly on both the upper and under side of the leaves. The egg is about -^ inch in diameter and marked with a series of ridges radiating from the apex. The eggs hatch in about four days and the young caterpillar, after eating its egg-shell, begins feeding on the leaf in which it eats out small holes. The larger larvae eat out irregular areas from the side of the leaf and when abundant often defoliate the plant. The caterpillar passes through seven stages in the course of its development and reaches maturity in about twenty-four days in warm weather. It is then about If inches in length, pale pea-green in color, inconspicuously marked with five narrow broken yellow lines above and with a broader yellowish white stripe on each side. While young the caterpillars suspend them- selves by a thread when disturbed and are able to climb back to the plant when the danger has passed. They walk with a peculiar looping motion owing to the fact that only four pairs of prolegs are present on the abdominal segments. When full- grown the caterpillar transforms in a folded leaf into a blackish brown pupa about f inch in length and in five days to two weeks depending on the season the moths emerge. In Florida the life cycle requires nearly five weeks. The caterpillars can be killed by spraying with arsenate of lead (paste), 2 pounds in 50 gallons of water. Recent experi- ments also indicate that effective work against the caterpillars can be done by spraying with " Black Leaf 40 " tobacco ex- tract, 10 ounces in 100 gallons of water in which 5 or 6 pounds of soap have been dissolved. INJURIOUS TO MINOR VEGETABLE CROPS 255 References Riley, Rept. U. S. Ent. for 1881 and 1882, pp. 167-170. U. S. Bur. Ent. Bull. 126. 1913. Dozier, Jour. Econ. Ent. 10, i)p. 536-542. 1917. Other okra insects Spinach aphis : 105 Corn ear- worm : 211 Stink-bugs: 232 Harlequin cabbage bug : 38 Green soldier-bug : 42 Nezara viridula : 43 Striped cucumber beetle : 109 Belted cucumber beetle : 1 15 Melon aphis : 135 Gray hair-streak : 84 Semi-tropical army-worm : 297 Red-spider : 351 Salsify The insects affecting salsify have not been carefully studied and those that have been listed as injurious to this plant are, as a rule, general feeders and have not been recorded as causing any serious injury to this crop. The following insects treated untler other crops have been reported as attacking salsify : Yellow bear caterpillar : 357 Tarnished plant-bug : 192 Yellow-striped army-worm : 295 Root-knot nematode : 338 Pepper Peppers are subject to attack by a number of insects that infest the potato, especially flea-beetles and the spinach aphis and potato aphis. The pepper weevil, Anthotwmus eugenii Cano In southern Texas and Mexico peppers are sometimes seri- ously injured by a small shining blackish or reddish black snout- 256 MANUAL OF VEGETABLE-GARDEN INSECTS beetle with a brassy luster, tV to | inch in length. The weevils are injurious in late summer and fall. In feeding they punc- ture the buds and young fruits with their beaks and the female deposits her small white oval eggs, about gV i»ch in length, in the cavities so made. The eggs hatch in two to four days and the young grubs feed on the surrounding tissue. The injured buds are blasted and the infested fruits usually drop pre- maturely. The grubs become mature in about two weeks. They are then about ^ inch in length, white and strongly curved. When about to pupate, the larva constructs a cell of excrement and bits of decayed tissue inside the fruit. The pupa is light amber in color, about ^ inch in length and rather robust in form. From six to ten days are spent in this stage. Soon after transformation the beetle leaves the pupal cell but remains within the fruit until thoroughly hardened, when it gnaws out an exit hole through the pod. The pepper weevil may be controlled by collecting and burning all infested fruits once a week during the egg-laying period of the weevils. It is not advisable to grow peppers year after year on the same land. In Mexico spraying with paris green is said to have been found of some value for the control of this pest. References U. S. Bur. Ent. Bull. 54, pp. 43-48. IQOf). U. S. Bur. Ent. Bull. 03, pp. 55-58. 1907. Other pepper insects Corn ear- worm : 211 Serpentine leaf-miner : 46 Spinach aphis : 105 Southern leaf-footed plant-bug : 121 Tomato worm : 168 Nezara viridula : 43 Belted cucumber beetle: 115 Colorado potato beetle : 142 INJURIOUS TO MINOR VEGETABLE CROPS 257 Potato aphis : 150 Common stalk-borer : 157 Garden flea-hopper: 77 Army-worm : 288 Semi-tropical army-worm : 297 Potato flea-beetle- 314 Western potato flea-beetle : 318 Root-knot nematode : 338 Red-spider : 351 Water-Cress Owiii