For Reference NOT TO BE TAKEN FROM THIS ROOM umlij'''''^''""' Hv > ^^-S^'^ ^A '^i-f' >?> v^\ .Private Pfopt% %f Z. p. METCALP .No. „ "''^'-^'^ry o^ ^ ^c:ac. LIBRARY OF IS85_I056 ^"^^ TCAl-^ 1^ p, ME INSECT PESTS OF FARM, GAEDEN AND ORCHARD BY E. DWIGHT SANDERSON DEAN OF THE COLLEGE OF AGPICULTURE, WEST VIRGINIA UNIVERSITY DIRECTOR WEST VIRGINIA AGRICULTURAL EXPERIMENT STATION FIRST EDITION TOTAL ISSUE, EIGHT THOUSAND NEW YORK JOHN WILEY & SONS, Inc. London; CHAPMAN & HALL, Limited X915 Copyright, 1912, BY E. DWIGHT SANDERSON PRESS OF BRAUNWORTH & CO. BOOK MANUFACTURERS BROOKLYN, N. Y. (La Mxj W\U PREFACE The edition of the writer's " Insects Injurious to Staple Crops/' first published ten years ago, having been exhausted, the pub- lishers requested a revision. It was found, however, that the advances in economic entomology during the past decade were such that it was necessary to practically rewrite the book. At the time it was first published two other books were projected; one to deal mth the insects affecting garden crops, and the other to discuss those affecting fruits. Pressure of regular work pre- vented the author from completing the manuscript for these works and in 1907 Dr. Chittenden issued his excellent book on " Insects Injurious to Vegetables," so that there seemed to be no immediate demand for another volume on that subject. At the same time two other well-known entomologists were work- ing upon books which would cover fruit insects, so that the writer abandoned the field to them. Subsequently, the work of one of these friends was cut short by his sudden death, and the other abandoned the task, at least for the present. Under these circumstances, it seemed that there was a distinct place for a book to cover all the insects affecting the crops of farm, garden and orchard, and having leisure to devote to it, the author developed the work in its present form. It has been the author's effort to discuss all of the more impor- tant insects of farm, garden and orchard at sufficient length to give a clear idea of their life histories and habits, and also the best means of control, so that the book may be used as a reference work both by the student of economic entomology and by the practical farmer, gardener, or fruit-grower. Insects of minor VI PREFACE or local importance have been purposely omitted. The insects of practically all of the leading crops are considered, except the citrous fruits. With these the author is unfamiliar, but it is hoped to add a chapter upon them by a competent authority in a subsequent edition. In general, the discussion of insects and their control as given is based upon conditions east of the Rockies, and practically no consideration has been given to the conditions of the Pacific Coast or of the irrigated country of the far West. The author is well aware that there are doubtless many errors of fact or of wrong emphasis in these pages. Such must nec- essarily be the case in a work the greater part of which must be compiled. All of the leading authorities on the subjects discussed have been consulted and the writer has endeavored to present their evidence fairly, with such interpretation as his personal knowledge made possible. He will be greatly indebted to those who will aid him in securing the accuracy of the work by report- ing any errors or by suggesting improvements in it, as it is hoped to revise the pages from time to time so that they may serve as a reliable reference work upon our insect pests of the farm, the garden, and the orchard. On the following pages are given the sources from which the illustrations have been secured, but the author wishes to express his special appreciation of the very large number of figures which were furnished him by Dr. L. 0. Howard, Chief of the Bureau of Entomology, and Mr. J. A. Arnold, Chief of the Division of Publications, of the United States Department of Agriculture, either as electrotypes or original drawings or photo- graphs, and to Ginn & Company of Boston for the loan of numerous electrotypes made for an Elementary Entomology by Prof. C. F. Jackson and the writer, now being published by them. E. DwiGHT Sanderson. West Virginia University, morgantown, SOURCES OF ILLUSTRATIONS The author wishes to express his very sincere appreciation of the courtesy extended him by those friends mentioned below who have furnished or loaned him electrotypes, photographs or drawings, thus making possible the anii)Ie illustration of this volume. From the United States Department of Agriculture, through the courtes}^ of Dr. L. O. Howard, Chief of the Bureau of Entomology and of Mr. J. A. Arnold, Chief of the Division of publications, the following illustrations were secured, either as electrotypes or as new plates made from the original drawings or photographs: Figs. 1, 2, 3, 4, 24, 50, 53, 55, 59, 61, 66, 83, 85, 86, 88, 90, 91, 93, 94, 95, 96, 101, 102, 103, 104, 105, 106, 110, 113, 114, 117, 124, 125, 126, 127,, 128, 129, 130, 131, 132, 133, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 148, 149, 150, 153, 154, 158, 159, 160, 161, 162, 163, 164, 167, 168, 170, 171, 172, 173, 174, 175, 176, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 192, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 211, 216, 218, 221, 222, 223, 224, 225, 226, 227, 228, 230, 231, 232, 235, 236, 240, 241, 242, 244, 246, 247, 248, 257, 258, 262, 264, 265, 266, 270, 271, 272, 273, 274, 277, 281, 283, 285, 292, 293, 294, 295, 296, 297, 298, 300, 304, 306, 307, 325, 326, 353, 354, 355, 356, 377, 379, 394, 395, 396, 398, 400, 401, 402, 404, 406, 413, 431, 432, 438, 446, 449, 472, 474, 475, 480, 487, 490, 496, 497, 502, 503, 504, 505, 508, and 512. The following illustrations were originally prepared by Dr. C. V. Riley and have been secured from various sources: Figs. 5, 7, 8, 9, 10, 12, 54, 60, 62, 63, 64, 65, 67, 68, 69, 74, 75, 76, 77, vij viii SOURCES OF ILLUSTRATIONS 78, 79, 80, 98, 99, 107, 147, 152, 212, 213, 214, 215, 220, 243, 259, 260, 261, 320, 473. Dr. S. A. Forbes, State Entomologist of Illinois, Urbana, 111., kindly furnished the following: Figs. 50, 51, 56, 58, 120, 121, 122, 123, 151, 156, 157, 234, 299. Prof. G. W. Herrick of the Cornell University Agricultural Experiment Station furnished electrotypes and photographs of the following illustrations by Dr. Slingerland: Figs. 57, 84, 87, 249, 250, 251, 253, 254, 338, 344, 345, 346, 347, 348, 360, 361, 362, 363, 364, 373, 381, 382, 383, 384, 422, 437, 482, 483, 485, 486, 495, 498, 499, 500, 501, 513. Prof. F. L. Washburn, State Entomologist of Minnesota, kindly furnished the following and also some of the figures of Dr. Riley listed above: 81, 330, 343, 350, 351, 378, 380, 491. Prof. H. A. Gossard of the Ohio Agricultural Experiment Station furnished the follo^ving: 89, 108, 341, 342. Prof. R. H. Pettit, Entomologist of the Michigan Agricultural Experiment Station, furnished the following: 92, 100, 245, and 341. Prof. C. P. Gillette, Director of the Colorado Agricultural Experiment Station, supplied figures 229, 239, 352, 439, 450, 506, 507, and 511. Dr. J. B. Smith, Entomologist of the New Jersey Agricultural Experiment Station, loaned the following and also some of the Riley figures: 13, 20, 109, 209, 210, 303, 308, 309, 323, 324, 327, 334, 335, 336, and 337. Prof. P. J. Parrott kindly sent photographs of the following from the files of the New York State Agricultural Experiment Station: Figs. 340, 349, 399, 465, 466, 493, 494, 509, 510. Prof. W. E. Rumsey of the West Virginia Agricultural Exper- iment Station kindly loaned photographs of the following: 357, 358, 359, 367, 368, 369, 370, 385, 386, 387, 388, 389, 441, 444. Prof. H. Garman of the Kentucky Agricultural Experiment Station furnished Figs. 97, 165, 166, and 238. Director R. W. Thatcher of the Washington Agricultural Experiment Station furnished Figs. 237, 328, 329, and 339. SOURCES OF ILLUSTRATIONS IX Dr. S. J. Hunter of the University of Kansas loaned electro- types of Figs. 112 and 113. Prof. T. B. Symons of the Maryland Agricultural Experiment Station loaned electrotypes of Figs. 119, 267, 310, 311, 312, 313, and 314. Prof.. H. E. Summers of the Iowa Agricultural Experiment Station loaned drawings of Figs. 154, and 333. Director P. H. Rolfs of the Florida Agricultural Experiment Station loaned photographs of Figs. 169 and 302. Director T. C. Johnson of the Virginia Truck Experiment Station furnished copy for Figs. 217 and 269. The Orange Judd Company of New York City kindly furnished electrotypes of Figs. 219, 301 and three of the Riley figures. Director J. C. Kendall of the New Hampshire Agricultural Experiment Station loaned the following electrotypes and several of the author's illustrations: 34, 43, 49, 118, 256, 322, 397, 417, 445, 447 and 448. Director S. W. Fletcher of the Virginia Agricultural Exper- iment Station and Dr. E. A. Back of the Virginia Crop Pest Commission furnished the following: Figs. 36, 393, 440, 442, and 443. Dr. W. E. Britton, State Entomologist of Connecticut, fur- nished electrotypes and photographs of the follo^ving: Figs. 41, 284, 305, 390, 416, 426, 429, 430, 477, 478, 479. Prof. R. I. Smith of the North Carolina Agricultural Exper- iment Station furnished photographs of Figs. 280, and 291. Prof. A. L. Quaintance furnished photographs of Figs. 282, 286, 287, 288, 289, and 290. Director F. B. Mumford of the Missouri Agricultural Exper- iment Station loaned Figs. 434 and 435. Prof. C. S. Crandall of the Illinois Agricultural Experiment Station, loaned drawings of Figs. 436 and 492. Messrs. Houghton, Mifflin & Co. furnished Fig. 221, from the Riverside Natural History. The Friend Manufacturing Company contributed Fig. 45. The Deming Company furnished Figs. 27, 28, 30, 33, and 39. X SOURCES OF ILLUSTRATIONS F. E. Myers & Bro. furnished Figs. 29 and 45. The Spramotor Company supplied Fig. 31. E. C. Brown & Co. donated Figs. 32 and 40. The Goulds Manufacturing Company supplied Fig. 46. The following figures are original or are the author's illus- trations: 6, 11, 14, 15, 16, 17, 18, 19, 23, 25, 37, 38, 42, 44, 46, 47, 48, 52, 70, 71, 72, 73, 82, 111, 134, 135, 177, 178, 179, 190, 191, 193, 194, 195, 196, 197, 233, 252, 255, 263, 268, 275, 276, 278, 279, 315, 316, 317, 318, 319, 331, 332, 391, 392, 403, 405, 407, 408, 409, 410, 411, 412, 414, 415, 418, 419, 420, 421, 433, 451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464, 465, 467, 468, 469, 470, 471, 481, 483, 488, and 489. CONTENTS Preface v Sources oe Illustrations and Ackno\vled(;ments vii CHAITER PAGE I. Injury to Crops by Insect Pests 1 II. Beneficial Insects, Predaceous and Parasitic U III. Structure and Development of Insects 22 IV. Farm Methods for the Control op Insects 32 V. Insecticides 42 VI. Spraying and Dusting Apparatus 60 VII. Insects Affecting Grains, Grasses, Forage and Mis- cellaneous Crops 79 VIII. Insects Injurious to Small Grains . 121 IX. Insects Injurious to Corn 157 X. Insects Injurious to Stored Grains 186 XI. Insects Injurious to Clover 200 XII. Insects Injurious to Tobacco 222 XIII. Insects Injurious to Cotton 241 XIV. Insects Injurious to the Hop-plant 273 XV. Insects Injuriolts to Potatoes and Tomatoes 285 XVI. InsECTS Injurious to Beans and Peas 305 XVII. Insects Injurious to Beets and Spinach 330 XVIII. Insects Injuriolts to Cabbage and Cruciferous Crops . . . 347 XIX. Insects Injurious to Melons, Cucltmbers, Squash, etc. . . 379 XX. Insects Injurious to Miscellaneous Garden Crops.... 402 XXI. Insects Injurious to the Sweet Potato 430 XXII. Insects Injurious to the Strawberry 441 XXIII. Insects Injurious TO the Raspberry and Blackb::rry. . . 459 XXIV. Insects Injurious to the Currant and Gooseberry 477 xi xii • CONTENTS CHAPTER PAGE XXV. Insects Injurious to the Grape 492 XXVI. Some Insects Injurious to Orchard Fruits 538 XXVII. Insects Injurious to the Apple and Pear 582 XXVIII. Insects Injurious to the Peach, Plum, Cherry ant) Stone Fruits 645 Index • 671 INSECT PESTS OP FARM, GARDEN AND ORCHARD CHAPTER I THE INJURY TO CROPS BY INSECT PESTS Ever since the locust plagues in the time of the Pharaohs his- tory is replete with accounts of insect scourges and the enormous losses they have caused the agriculturists of all ages. However, instead of diminishing with the advancement of agricultural methods, injurious insects have undoubtedly become both more numerous and more destructive in modern times. " In no coun- trj' in the world do insects impose a heavier tax on farm products than in the United States. The losses resulting from the depre- dations of insects on all the plant products of the soil, l)oth in their growing and in their stored state, together with those on live stock, exceed the entire expenditures of the National Gov- ernment, including the pension roll and the maintenance of the Army and the Navy."* " Very careful estimates, based on crop reports and actual insect damage over a series of years, show that the loss due to insect pests of farm products, including fruits and live stock, now reaches the almost inconceivable total of $1,000,000,000, annually. "t The above quotations from Mr. C. L. Marlatt, Assistant Chief of the Bureau of Entomology, * C. L. Marlatt, Yearbook U. S. Department of Agriculture, 1904, p. 461. t C. L. Marlatt, Journal of Economic Entomology, IV, 109. 2 INSECT PESTS OF FARM, GARDEN AND ORCHARD United States Departnient of Agriculture, may appear to the reader either kidicrous or startHng, according to whether he be more or less informed concerning the important role which insects play in our agricultural economy, which in turn forms the warp of American prosperity. A brief resume of the records of damage done by insect pests, of the cost of fighting them, and of the estimates which form the basis of the above statement, will make it the more convinc- ing. Growing Cereals. — Probably no other insect does so widespread damage as the Hessian fly, attacking our chief staple, wheat, as well as rye and barley. One-tenth of the whole crop, valued at $50,000,000 to $70,000,000, is generally conceded to be de- stroyed by this pest every year. In certain sections the loss often amounts to from 30 to 50 per cent, and in 1900 was estimated at fully $100,000,000 (Marlatt, I.e.). The southern grain louse or " green bug " caused a loss estimated at from $5,000,000 to $10,000,000 in Texas, Oklahoma and Kansas in 1907, and every year there is a considerable shrinkage of the wheat crop due to the work of various species of plant-lice whose injury doubtless amounts to 2 or 3 per- cent of the crop, worth $15,000,000 to $20,000,000. The corn crop of the United States was worth $1,720,000,000 in 1909. One of the worst pests of this crop in the Mississip])i Valley is the (diinch-ljug. Several years ago Professor F. M. Webster estimated the 'loss from this insect since 1850 at $330,000,000, and at present it probably destroys at least 2 per cent of the corn crop every year, worth over $30,000,000, and in many years the loss is much more. The western corn root-worm and the corn root-aphis which work unnoticed on the roots of the corn throughout the same territory cause an equal loss. The corn ear-worm often destroys from 5 to 10 pei- cent of the crop in the South, and throughout the Corn I^qM it undoubtedly decreases the crop by 2 or 3 per cent. The total value of cereal crops in the United States in 1909 was practically $3,000,000,000, which was undoubtedly decreased THE INJURY TO CROPS BY INSECT PESTS 3 by 10 per cent due to the ravages of insect pests, which thus taxed our grain growers some $300,000,000. Hay and Forage Crops. — A host of small insects attack our grasses and forage crops, many of them being so small that they are unnoticed, though their aggregate injury is something enormous. Of the larger pests of grasses and forage plants the army worms are among the best known and have often caused a loss of over half a million dollars to a single State in one season. Grass- hoppers of various species are also always more or less injurious and often become a serious menace. Probably the most serious injury, however, is done by subterranean larvie such as the cut- worms, wireworms, white grubs, and webworms, which breed in sod land, and by the hordes of little leaf-hoppers which are always prevalent, but whose injury often passes unnoticed. Ten per cent of the hay crop was worth $65,000,000 in 1909, and this is a fair estimate of the damage done to ha}' and forage crops by their insect enemies. Cotton. — The cotton plant has a number of injurious insect enemies, of which the boll weevil, bollworm, and leafworm are the most injurious. In 1904 the writer made a statistical study of the decrease in the cotton crop of Texas due to the boll weevil, and showed that it was then costing that State $25,000,000 per annum.* This estimate has been confii-med by independent investigations made by Mr. W. D. Hunter of the U. S. Bureau of Entomology, and although the loss in Texas is not so serious at present, the weevil has spread eastward into Alabama, so that its total injury remains practically the same, and has undoubtedly l:)een a large factor in the higher price of cotton in recent years. The bollworm is most injurious in the south- western cotton-producing States, where it causes a loss of from 5 to 60 per cent of the crop. The total damage to cotton by the l^ollworm is approximateh^ $20,000,000 per annum and not infreciucntly exceeds that amount. In ISSO the United States * E. D. Sanderson, The Boll Weevil and the Cotton Crop of Texas. (Bul- letin Dept. of Agriculture, Insurance, Statistics and History, Austin, Texas, 1905, p. 28, 7 maps.) i INSECT PESTS OF FARM, GARDEN AND ORCHARD Entomological Commission made an investigation of the cotton worm and valued its ravages at S30,000,000, but with the extensive use of Paris green and arsenical poisons its injury has been greatly reduced and now amounts to from $5,000,000 to $10,000,000 annually. Various minor pests of the cotton plant inflict a considerable amount of local injury and with the above pests damage the crop at least 10 per cent, worth $85,000,000 in 1909. Tobacco. — Tobacco is attacked by insects, which form one of the chief " bugbears " of tobacco growing, at all stages of its existence. Ten per cent of the crop, worth $10,000,000, is cer- tainly destroyed by them every j^ear. Truck Crops. — Truck crops are peculiarly susceptible to insect attacks, and their control forms one of the chief items in the cost of production. It is safe to say that truck crops suffer from insect ravages full}^ twice as much as do the staples, or 20 per cent of their total value. Statistics are not available for the present value of truck crops, but they were probably worth $300,000,000 in 1909, making the insect tax for the trucker fully $60,000,000. Fruits. — Fruit trees are also much more seriously injured by insects than are the staple crops, and their control involves a large expense to the fruit-grower. Where it is not combated, the codling moth, or apple worm, would cause a loss of from 30 to 50 per cent of the crop, and where it is controlled by spraying a consideral)le expense is involved. The loss and cost of treatment for this pest alone amount to $20,000,000 for the United States, and were it not for the fact that it is now largely controlled in the principal fruit-growing sections, the loss would be double or treble this sum. The loss due to the San Jose scale is difficult to estimate, but it is well known that it has destroyed millions of trees and that in the principal fruit regions where this pest is prevalent it is necessary to treat the trees annually at a cost of from 10 to 25 cents per tree, so that $10,000,000 a year would be a very conservative estimate of its annual cost. Both deciduous and citrous fruits have a host of insect pests, THE INJURY TO CROPS BY INSECT PESTS 5 always present and doing more or less damage and occasionall}' becoming so abundant as to threaten the life of the trees or their crops. Twenty per cent of the value of our fruit products, worth at least $30,000,000, is certainly destroyed by insect pests every year. Forest Insects. — Only those who have had opportunity to observe the ravages of insects in timber and in timber products can appreciate the enormous losses which they occasion. Prob- ably no one is better informed upon this matter than Dr. A. D. Hopkins, in charge of the Forest Insect Investigations of the I'. S. Bureau of Entomolog}', who has made a life study of these pests in all parts of the country. In a recent circular he states * that " the amount of insect-killed and damaged timber left in the woods, plus the reduction in value of that utilized, to be charged to insects is not far from an equivalent of 10 per cent of the value of the annual output of forest products of all kinds, in the rough. The total value of the forest products of the United States in 1907 is given as $1,280,000,000; the losses from insect depredations would therefore represent an annual loss in cash value of more than $100,000,000." To this should be added a similar loss to farm woodlots, which may be estimated at an additional $10,000,- 000. The insect injury to the shade trees of city streets, parks, and estates should also be mentioned, for such pests as the gypsy moth, the elm leaf-beetle, tussock moths, etc., are not only causing enormous losses and large expense for their control, but they are often destroying the values of real estate and through killing the trees are destroying the scenic value of property and changing the esthetic environment in a manner which it will require many decades to remedy, if the previous conditions can ever be even partially reproduced. The State Forester of Massachusetts has recently shown that the New England States and the Federal Government have spent fully $7,000,000 in fighting the gypsy and brown-tail moths in New England, and at the present time the New England States, the Federal Government, municipalities and private individuals are spending fully $1,000,000 per annum * A. D. Hopkins, Circular 129, Bureau of Entomology, U. S. Dept. Agr, 6 INSECT PESTS OF FARM, GARDEN AND ORCHARD in this warfare for the preservation of their shade and forest trees. Live Stock. — Insect pests, incUiding the ticks and mites, are almost as important as enemies of live stock as of crops. The principal drawback to cattle raising in the South is the Texas fever, transmitted by the cattle tick, which has been charged by the officials of the Bureau of Animal Industry with a loss of SlOO,- 000,000 annually. The ox-warble, which causes the "grubby" hides of cattle, causes a loss estimated at from S10,000,000 to $35,000,000 per year due to the depreciated value of the hitlos and the lessened quantity and poorer quality of the beef of affected animals. The screw-worm fly is a constant annoyance to cattle and source of loss on the range, and numerous biting and parasitic flies cause a considerable loss to the grower of live stock, both through actual damage and through the annoyance preventing growth and production. The sheep scab, sheep tick, the sheep bot — causing ''staggers" or "grub-in-the-head" — horn-fly, buffalo-fly, black-fly, and numerous species of lice which affect all of the domestic ani- mals, are among the pests which must be combated by the stock- man. In 1909 the live stock products were worth $3,000,000,000, and it is estimated that fully 10 per cent of this amount was lost through injury from insects. Stored Products. — Even after the crops have been gathered and garnered, and indeed after they and animal products have been manufactured, they are constantly subject to the attacks of numerous "weevils," "moths," and other insect pests of stored products. Every housewife and every merchant knows that only through constant surveillance can they prevent these ravages. Mills, tobacco warehouses, storage houses, and vessels, must be frequently cleaned and often must be fumigated to prevent the increase of insect pests peculiar to them. It is estimated that at least 5 per cent of the cereal crops are destroyed by insects while in storage, which would mean a loss of $150,000,000, and in many cases the loss to corn, particularly in the South, is much greater. The total loss due to insects in stored goods of all kinds is impos- sible to estimate, but would fall not far short of $200,000,000. THE INJURY TO CROPS BY INSECT PESTS With this brief survey of the losses thie to iiis(>ct pests, we may summarize them in a table which will show that the total is based upon conservative estimates. Annual Values of Farm Products and Losses Chargeable TO Insect Pests * Product. Values. Percentage of I-oss. Amount of Loss. Cereals $3,000,000,000 665,000,000 850,000,000 100,000,000 t 300,000,000 95,000,000 t 150,000,000 110,000,000 t 100,000,000 3,000,000,000 10 10 10 10 20 10 20 10 10 10 $300,000,000 66,500,000 85,000,000 10,000,003 150,000,000 9,500,000 30 000 000 Hay and forage . . Cotton Tobacco Truck crops Sugars Fruits Farm forests 1 1 000 000 Miscellaneous crops 10 000 000 Animal products 300,000,000 Total Natural forests and forest products $8,370,000,000 $972,000,000 100,000,000 200 000 000 Products in storage Grand total $1 272 000 000 * Basccl upon table of C. L Marlatt, I.e., niodifi;'d by stati.stio.s of the Secretary of Agriculture, Yearbook V . S. Department of Af;riiultnre for 1909. t E.5timated. One l)illion dollars is thus a conservative estimate of the damage done to staple crops, fruits, truck crops, domestic animals, timber and stored products by these apparently insignificant insects. Yet there is another aspect to the matter. " One man's loss is another man's gain" is never more true than as regards these losses occasioned by insects; for, through widespread injury by them, prices rise, while if these injuries did not occur and corre- spondingly large crops were placed upon the market, prices must surely fall. These estimates of losses due to insects are then very largely comparative. Yet, to a large extent, they are still real losses, the same as are those occasioned by fire and storm; for 8 INSECT PESTS OF FARM, GARDEN AND ORCHARD though a .siuall crop iiuiy l)iing better prices, it is usually at the expense of individuals or communities which have sustained ex- ceptionally heavy losses. Were these losses evenly distributed among all those producing a given crop, there would be no real hardship to them; but such is by no means the case. All this, then, goes to emphasize the fact that the successful farmer — as the successful man in any other trade or profession — is the one who is able to overcome obstacles which, though pos- sibly ruining his neighbor, are making a good market for his special crop; for these insect pests can be largely overcome. The millen- nium will doubtless come before the farmer will be able to stop fighting them, but a large part of the damage by them can be pre- vented at a cost which renders it profitable. Rational methods of general farm practice with the proper use of apparatus and insecti- cides, even such as are now known, and in which improvements are being constantly made, if intelligently used l)y American farmers, would save to them the larger part of this enormous loss. CHAPTER II BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC Ladybird-beetles After liLs tstra\vbc'ni(\s have been luincd by the stiawbeny weevil, the garden truck l)y eutworms, the wheat despoiled by the Hessian fly, the melon-patch fallen a pre}' to plant-lice, and the fruit crop has been a failure on account of the codling moth, plum curculio, and San Jose scale, it is scarcely surprising that the farmer does as one of my acquaintances did and "orders the hands to kill everything that craw^ls." But such would be entirely too heroic a measure, and if strictly adhered to the remedy would be as bad as the disease, for it would mean not only useless labor, but the destruction of the most effect- ive means whereby insect pests are held in check. We pride ourselves — and justly — that with our spray pumps and deadly sprays many crops can be effectually protected; but were it not for those other insects which feed upon these injurious forms, what an enormous, and, in some instances, almost futile task it would be ! Among these beneficial insects the little ladj'bird-beetles of the family Coccinellidce are entitled to be in the first rank. Almost all the beetles and larvae feed upon plant-lice and scale insects. Of such value are those feeding upon scale insects that not many years ago several Australian species were imported into California that they might prey upon the San Jose and other scales. One of these was eminently successful and almost completely destroyed the cottony cushion-scale. Of those feeding upon plant-lice, one of the most common is the Nine-spotted Ladybird (Coccinella novemnotata). This 9 10 INSECT PESTS OF FARM, GARDEN AND ORCHARD beetle is about one-fourth of an inch long, with black head and body. The wing-covers are orange-yellow marked with nine black spots — four on each side and one on the central suture. The larva has been fancied to resemble a miniature alligator; it is nearly twice as long as wide, almost black, marked with bluish and orange spots, and has long legs, which carry it around quite rapidly. The beetles hibernate during the winter and come forth in the spring and lay their eggs wherever the young will be able to find food when they hatch. When the larva has satisfied its ravenous appetite and become full grown it fastens itself to a leaf or twig, — sceminglv Ijv its tail, if such Fig. 1. — The nine-spotted ladybird {CoccineWi novcnmotatu), and its larva enlarged. (After Chittenden, IT. S. Dept. Agr.) a term might be allowed, — transforms to the pupa, and in a week or ten days the adult beetle emerges from the pupal skin. This life-cycle is repeated several times during the summer season, before the fall brood enters winter quarters. Another very common form among plant-lice on garden truck is the little Adalia bipunctata, or Two-spotted Ladybird. It is slightly smaller than the preceding, and with only one black spot on each wing-cover (Fig. 2) . Several other species in the genus Hippodamia are very useful, and among them the Convergent Ladybird (Hippo- damia convergens) is one of the Ijcst known. Its name is received from two white dashes on the ])lack thorax, which converge posteriorly. The thorax lias also a white nuirgin, and there are BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC 11 thirteen black clots on its orange wing-covers. These larvae and beetles are very common among the plant-lice on melon- vines, and are an important factor in their extermination. They -ym-. Fig. 2. — The two-spotted hu\y\nrd {Adalia bipunctata): «, l;irv;i; 6,- mouth- parts of same; c, claw of same; d, pupa; e, advilt; /, antenna of same; all enlarged. (After Marlatt, U. S. Dept. Agr.) Fig. 3. — The convergent ladybird {Hippodamia convergenfi) : n, adult; h, pupa; c, larva; enlargeil. (After Chittenden, U. S. Dept. Agr.) have also been noted for eating the black peach aphis and many other plant-lice. A form which is often very al)undant among plant-lice on corn is the Spotted Ladybird {Megilla maculdta). The head, thorax, and wing-covers are a dai'k pink, with two black spots on the 12 INSECT PESTS OF FARM, GARDEN AND ORCHARD thorax and ten on the wing-covers. Such nuniljcrs of these little fellows have frequently been found huddled together under the rubbish at the base of some tree in a last year's cornfield that they might be taken up by the handful without difficulty. Fig. 4. — The spotted ladybird {Megilla maculata): a, larva; 6. pupa;.c, adult; enlarged. (After C'.ittenden, U. S. Dept. Agr.) Many other species feed upon plant-lice, but the al:)Ove are the most common, and all bear a resemblance to one another, being generalh' orange or red with black spots, and of a characteristic round or oval form, flattened below. so that the legs may be drawn in luidcr the wing-covers. Those ladybirds which feed upon scales are much smaller and are Fig. 5. -The twice-stabbed ^^1'^^"^' though sometimes spotted ladybird {Chilocorus bivulnc- with red or orange. ?w.s). a, adult; b, larva; en- v r i j.i ,. • ,1 T^c. r.-i N As far as known, there is no larged. (After Riley.) _ ' wav in which these useful allies may be encouraged or increased in luimbers, but it is trusted that the above ma}^ give such a brief view of their habits that fewer may be killed through ignorance concerning their true worth, BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC 13 Syrphus-flies Besides the little beetles described al)0\'e there is a family of flies, the Syrphidoe, many of whose larva- feed upon plant- lice. This family is a very large on(\ and thus the habits of its tlifferent members vary considerably. One of them, the drone- fly, so closel}' reseml^les a hone}'- bee as to be almost indistin- guishable from it. The larva of this fly (Eristalis tenax) is one of the common rat-tailed mag- gots which are found in putrid matter. It is thought .that the old " bugonia " superstition of ^^^^ ^ c ;., •; ■■ i i <= ^ riG. 6. — j>iyrp/nis ribefiit ; enlarged. the ancients that bees came from maggots in dead aninmals, etc., was due to the confusion of this fly with honey-bee. In another group of the family, the adult flies of which also quite closely resemble bees, the larvas are parasitic in the nests of honey- and bumble-bees, feeding upon their larVcC. But the larvse of possibly the most typical portion of the family, embracing the genus Syrphus and its near allies, are entirely predaceous upon plant-lice. Rarely can a colony of plant-lice be found without some of these little enemies hard after them. The adult syi'phus-fly is a very sti'iking insect, \\\\h its dark green metallic thorax, and abdomen variously banded with yellow and black. The female fly lays her eggs upon some plant bearing plant-lice. The larvse which hatch from tliese are elongate, flattened maggots, about one-half an inch long, with hardly a trace of a head, but with four small hooks, which serve as jaws, projecting from the more pointed end of the body. These mag- gots are often of a light-green color, and so like the color of the plants as to render them most difficult to recognize. The young larvffi at once commence crawling over the plant in search of aphids, and as soon as they come in contact with one it li INSECT PESTS OF FARM, GARDEN AND ORCHARD is firnil}' chispcd l)y the small liooklets until the juices are sucked from its l:)0(ly. In this manner \'ery large numbers are destroyed, a single maggot of the American Syrphus-fiy {Syrphus americanus) having been observed to eat twenty-five apple plant-lice {Aphis pomi) in as many minutes. When the larva is ready to pupate it attaches itself to a leaf, and the larval skin dries up and forms a case or puparium inside of which the pupa remains until it transforms to the adult fly. Though most of these larvaj feed upon plant-lice upon the leaves, one of them, the Root-louse Syrphus-fly {Pipiza radiccms), lives entirely underground during that stage, and feeds upon Fig. 7. — The root-louse syrphus-fly {Pipiza radicans). a, maggot; b, puparium; r, fly. (After Riley.) the root-lice of the apple and the grape. None of this family are injurious, uiid as a larg(> portion of them ai'e so ben(>ficial as to frequently destroy whol(> bioods of ])laiit-lire, they should not be (listurl)ed in their good Moik if ])ossible to avoid il. The Ground-beetles If, as you scrape away the loose chips at the base of a tree in your door-yard, turn over an old log in the woodland, or pick up a fallen fence-rail, you will scrutinize the inhabitants under these shelters, a number of shining black beetles varying in length from one-fourth to 1 h inches will usually be noticed. If the city reader be not so fortunate as to be familiar with or have access to these hiding-places, he may find large numbers of the beetles under any electric arc light during the warm summer evenings; for there they are having a sumptuous banquet upon the small BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC 15 flies and moths attracted by the glare. The}' are rarely seen at large during the day, as they are almost exclusively nocturnal insects, and from their habit of remaining almost entirely in or on the ground they are usually known as " Ground-beetles." As might therefore be inferred, they are exceedingly valuable to the farmer by destroying large numbers of noxious insects which pass a part or all of their existence in the soil. Besides the glossy black forms which are most commonly seen, many are brillianth' marked with gold, green, purple, and iridescent tints. The Fiery Ground-beetle {Calonoma calidum), so called on Fig. S. — The fiery ground-beetle {Cidoaoina culidum). a, beetle; b, larva; c, " the searcher " (Calosoma scrutator). (After Riley.) account of the wing-covers being dotted with bright gold, has many times been of great assistance in helping to rid a corn-field of cutworms. The larvae of this insect are about one inch in length, of a dark brown color, with the skin of a hard, horny texture like that of the beetle. They have strong, prominent jaws, and at the posterior end of the body is a forked appendage looking much like another pair of jaws. It is not only surpris- ing that these larva will eat so large a number of cutworms, as they have frequently been known to do, but that they will dare to attack such a formidaljle creature fully three or four times as large as themselves, but their assault is sharp and vigorous, and a single larva has often been seen to kill and eat 10 INSECT PESTS OF FARM, GARDEN AND ORCHARD several full-grown cutworms in a short time. Many instances of the good work of this beetle are on record, among which one by the late Professor J. A. Lintncr may be cited, where he found them eating large numbers of the corn-cfambus — sometimes locally known as the corn bud-worm. Another somewhat larger beetle, called by Professor J. H. Comstock '' the Searcher " {Calo- soma scrutator), and in fact one of the largest of the family, is a brilliant metallic green, bordered with a dark purplish-blue, and has the good quality of having a very particular appetite, causing it to kill large; numbers of caterpillars, l)ut eating only part of each. While in the earth as pupa) large numbers of the Colorado potato-beetles are destroyed by members of this family, and one species, Lehia grandis, which is peculiar in that the wing-covers are somewhat a]3breviated, thus leaving the tip of the alidomen exposed, has been noticed on the plants eating the eggs and young larvie of this old potato pest. Another valuable species is one called by Dr. Riley the Murky Ground-beetle (Harpalus caliginosus) . Its larva is of considerable assistance to fruit-growers by eating Fig. 9. — Lebia gran dis. (After Riley.) Fig. 10. — The murky gmuiul-beetlc {Harpalus caliginosus): adult at left; a, larva; b, head of same; c, mandible. (After Riley.) large numljcrs of curculio larvie, which it secures from the plums after they have fallen to the earth. From a glance at its formid- able jaws. Fig. 10, b-c, it is easy to conjecture the fate of many a curculio grub. BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC 17 Thus here again are found some "bugs" that are friends and not foes, worthy of all the protection that can be afforded them, and well repaying such careful observation of their habits as may be bestowed upon them. Insect Parasites Though large numbers of injurious insects are annually de- stroyed by those which are purely predaceous upon them, many more succuml^ to those minute forms which live parasitically within them. A few of these pai'asites belong to the order Dip- tera, or true flies, but most of them are classed in the order Hymen- optem, in which order are also included the saw-flies, ants, wasps, and bees. Of the half-dozen families of hymenopterous parasites one of the largest and most beneficial is that of the Ichneumon-flies. The illustrations will best show the form and structure of these insects, which the casual observer will hardly be able to disti-nguish from other families of the group. But it will be noticed that the fine veins of the wings vary consideral)ly in the different parasites figured, and it is by these that the entomologist is enabled to separate the different groups and often to iden- ^^'^- H.— Maggots of Pnnjdn inquisitor, a , -f ,, . ^ , parasitic Iclineum on-fly, feeding on a cater- tify the species at a glance. piUa,. which had spun its cocoon and was Both this and the follow- ready of pupate, ing family are peculiar in having an exceedingly long ovipositor or egg-tube, of which they make a very good use. It is with this extensile tube that the female deftly punctures the skin of some unsuspecting cater- pillar, and under it inserts her eggs. In a few days there hatch from these a host of young maggots which feed upon the juices and 18 INSECT PESTS OF FARM, GARDEN AND ORCHARD tissues of the caterpillar, but nre seemingly careful to avoid injur- ing any of its vital organs, for as soon as the caterpillar reaches its full growth it changes to a pupa, apparently unaffected. When the maggots have reached their full size each spins up a small silken cocoon inside the pupa, entirely filling up its now dead shell, and instead of a beautiful moth appearing in the spring, a horde of small flies are seen to emerge from a round hole in the side of the pupa, or cocoon. Thus large numbers of such pests as the apple-tree tent-cater- pillar (Clisiocampa ameri- cana), bagworms (Thyridop- teryx ephemerceformis) , cater- pillars of the swallow-tailed l)utterflies which feed upon parsley, carrots, etc., and a host of others, are consumed by members of this family. Those belonging to the genus Ophion are partial to the large American silkworms which produce some of our largest and most ])eautiful moths, and difficulty is fi'e- (juently experienced in I'ear- ing a desired number of moths on account of the large per cent of cocoons parasitized. The species of the family Braconidce are very similar to those of the preceding one, and contain some equally beneficial insects, feeding as they do upon such pests as the codling moth, webworms, plum-curculio grubs, plant-lice, etc. Some of the more common foi-ms of this family belong to the genus Microgaster, and their small white cocoons may frequently be seen almost covering one of our large tomato- or tobacco-worms (see page 234), the pupa? of which are often known as "horn-blowers." Many mistake Fig. 12. — The long-tailed Ophion {Ophion macrurum). a, advilt; b, maggot; enlarged. (After Riley.) BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC 19 these cocoons for the eggs of the worms, and therefore destroy some of their best friends. Though some thus spin their cocoons on the outside of the host, others remain inside of the parasitized insect until the adult fly emerges. Thus dead plant- lice may often be found with a large round hole in the ab- domen — the onl}' evidence, of where one of these para- sites has emerged. For this reason dry, shrunken plant- lice should never be de- stroyed. The Chalcis-flies, which comprise another closely re- lated family, are exceedingly minute insects, sometimes not over one one-hundredth Fig. 13.— A plant-louse parasite (Aphidius of an inch lono-. They are avenaphis) , showing above the parasitized '^ IT I'l louse from which it has issued. (Copied generally of a metallic black from J, B. Smith.) color, and the usual veins of the wings are almost entirely absent. Many of these flies are parasitic upon plant-lice, while a large number of their larvae live and mature in the eggs of other insects. Very similar to the chalcis-flies in their habits of infesting plant-lice and insect eggs are some even smaller insects — in fact the smallest known, the largest being rarely over one-twenty-fifth and the smallest only six- or seven- one-thousandths of an inch in length — with a correspondingly tremendous and unpronounceable name, known to science as the Proctotrypidcc. During the last half century the American farmer has been compelled to contend with an increasing number of insect pests, which now and then have become veritable scourges. Every now and then we hear of communities assembling for prayer and fasting to appease the Almighty, whose wrath has hurled a new insect plague against them, but such a procedure is b}- no means as com- 20 INSECT PESTS OF FARM, GARDEN AND ORCHARD mon as formerly, and little reflection will show that these scourges are entirely due to natural causes. In fact they are very largely brought about by man himself. Some of these pests are due to the fact that in trying to subdue nature by clearing and cultivating the land, man has deprived the insects of their natural food plants. They must, therefore, needs feed upon that which is substituted by him, and as it is less abundant than the former wild vegeta- tion, the number of insects and the inj ury they inflict are more apparent. By far the larger number of our worst pests, however, are those which come to us from foreign shores. Foreign insects are con- stantly being imported in one way or another, sometimes being already established pests in other lands and sometimes only becom- ing so under their new surroundings. These are even moi-e injuri- ous than those native, for whereas many of our native birds, in- sects, and diseases constantly prey upon native insects and thus keep their numbers in check, the enemies of imported pests rarely accompany them, and they thus increase at an alarming rate and do enormous damage before they are attacked by the natural enemies of similar native pests. It is in the case of these imported pests that the value of parasitic and predaceous insects is most apparent. In an effort to make use of them to fight the gypsy and brown-tail moths in New England, the U. S. Bureau of Ento- mology has for several years been importing large numbers of the parasites and predaceous enemies of these pests and liberating them in affected regions, thus carrying on a practical experiment on a large scale which may show the importance of these parasites in combating imported pests. Even with our native pests, however, we have frequent exam- ples of the value of parasitic and predaceous enemies. Thus the southern grain louse, or "green bug," was soon brought under control by the myriads of little parasites which preyed upon it (see page 155), and these were artificially transported for some distance and liberated in large numbers. Though these efforts at the distribution of this parasite may be open to some question as to their effectiveness, other parasites have been successfully BENEFICIAL INSECTS, PREDACEOUS AND EARASITIC 21 distributed, and there can be no question that before long we shall come to better understand how we may make use of these valuable allies, and some day we may be able to duplicate the apparent miracle by which Dame Nature sweeps away an insect plague in a few da3's with the aid of these apparently insignificant parasites. CHAPTER III STRUCTURE AND DEVELOPMENT OF INSECTS The more experience the farmer has with insect pests, the more he comes to realize that if he would successfully combat them, he must have a certain amount of necessary knowledge concerning their structure and growth. • In general, the artificial means which may be effectually used to combat an insect pest will depend more or less upon the anatomical structure of the insect, while control by general methods of culture will depend upon a knowledge of the peculiar- ities of its life-histor}'. The value of a proper understanding of these important factors in insect control is therefore apparent. General Structure of an Insect The body of an insect is composed of three separate parts, the head, thorax, and abdomen (Fig. 14), each of which is com- posed of several rings or segments. To the head are attached the jointed antenna?, or feelers, the compound eyes, and the mouth- parts, which are described below. Each of the three segments of the thorax Ijears a pair of legs, and adult insects usually possess one or two pairs of wings upon the Fig. 14.-Houey-bee, showing the ^^st two segments of the thorax, three principal regions of the body The abdomen is composed of nine of an insect: — h, head;fA, thorax; abd, abdomen. the females of certain orders. or ten segments, but bears no appenda^s- save. fJie ovipositor of 22 STRUCTURE AND DEVELOPMENT OF INSECTS 23 Harvest-mites, or " daddy-long-legs," sow-bugs, thousand- legged worms, and similar vermin are often popularly called insects, but all of them can readily be distinguished from true insects by their jjossessing more than six legs,, the ha^vest-miteS and spiders having eight and the others many more. How Insects Grow With rare exceptions insects hatch from eggs laid b}' the adu't females. Upon hatching they are but little larger than the eggs, and often bear but little resemblance to their parents. Thus the young caterpillar would never l)e recognized as the immature stage of the butterfly by one unfamiliar with its transfor- mations. Grasshoppers and some other insects, however, upon hatching from tiie egg bear a marked resemblance to the adult form, except that they lack wings. Complete Metamorphosis. — When the caterpillar hatches from the egg it at once commences to feed and grows very rapidly, liut 1)efore long an obstacle to further growth arises. Unlike higher animals, insects possess no internal skeleton or framework for the organs of the body, but the outer skin becomes hardened and to it the muscles and ligaments are attached. This hardening of the skin is best seen in the horny wing-covers of the beetles, and is due to the secretion of a hard substance called chitin. This chitin is secreted by all parts of the skin in greater or less degree, and thus forms a sort of shell for the whole body. Though this hardening is not so apparent in larvae as in adult insects, it is always present, and it is for this reason that when the young caterpillar has made a certain growth it is forced to shed its skin, which refuses to expand further, in order to develop more fully. Thus the skins of insects are shed several times (see Fig. 15, 6), — usually five or six, but sometimes as many as twenty, this process being known as moltinj. During its life as a caterpillar, which is called the larval slaje, and during which it is called a larva, it is an elongate, worm-like creature, with six short, jointed legs on the three thoracic segments, a pair of fleshy false legs or pro-legs on the last abdominal segment, and probably 24 INSECT PESTS OF FARM, GARDEN AND ORCHARD several pairs of pro-legs between these and the true legs. No traces of wings can be seen, but the body is often covered with hairs, spines, or warty tubercles. With the next molt the insect changes in appearance most radically, becoming a 'pu'pa, or chrysalis, as this stage is termed Fig. 15. — Complete metamorphosis. The different stages of the com ear- worm (Heliothis obsoleta Fab.): a, eggs on corn-silk; b, the first tnree larval stages; c, pupa from below; d, same from above; e, adult moth — all enlarged; b, about twice natural size, for butterflies. During the pupal stage the insect remains dormant either in a small cell slightly under the surface of the earth, or in a silken cocoon spun l^y the caterpillar, or merely attached to the food-plant by a strand of silk or the cast larval skin. In many of the Diptera, — the order including flies, mos- quitoes, gnats, etc., — however, the last larval skin is not shed, STRUCTURE AND DEVELOPMENT OF INSECTS 25 but hardens and forms a case — called a puparium — within which the pupal stage is passed. The typical pupa (Fig. 15, c, d) of a butterfly or moth re- sembles neither the adult insect nor the larva, is of a more or less oval shape, with the wings and antenna tightly folded at Fi; 16.^ — Incomplete metamorphosis of a bug {Brachymena ■i-pusttilata) : a, eggs; b, adult bug; c, different stages of young bugs or nymphs. the sides, the legs drawn up snugly together under them, and the head and mouth-parts bent upon the breast, or sternum, though all of these parts are not always recognizable, the legs and mouth- parts being sometimes lacking. Gradually the adult insect develops, and at last the pupal skin is broken open and the airy l)\itterfly emerges to enjoy a short life and perpetuate the species. 26 INSECT PESTS OF FARM, GARDEN AND ORCHARD Such a series of transformations is that commonly found among butterflies and moths (Lepidoptera), beetles (Coleoptera), flies (Diptera), and bees (Hymenoptera), and is known as a complete metamorphosis. All of these insects normally pass through four stages, of egg, larva, pupa, and adult. Incomplete Metamorphosis. — In contrast to this mode of development is that of the grasshoppers (Orthoptera), bugs (Hcmiptera), and some other insects. As already stated, these are much like the adult upon emerging from the egg. With each molt they become larger and small wing-like pads gradually appear on the sides of the thorax. There is no dormant or pupal stage, the adult insect differing from the previous stages in hav- ing fully developed wings, being larger, and often by an accompany- ing change of markings. The immature stages of such insects are called nymphs, and this development an incomplete meta- morphosis, having but three stages, of egg, nymph, and adult (Fig. 16). The time occupied l)y the complete life-c}'cle of an insect varies from a week or ten days for the plant-lice to thirteen or seventeen years for some cicadas, and is entirely dependent upon the habit of the species and the climate. A correct knowl- edge of the exact time and conditions under which the trans- formations occur for each individual insect pest is therefore often most essential when seeking means for its control. How Insects Feed The material to l^e used in combating a given insect is largely dependent upon the structure of its mouth-parts. Much Paris green is wasted upon insects unable to eat it and which it will, therefore, never kilL Insects may be roughly divided into two classes, those which bite and those which suck their food. Among the fornun- are the beetles, grasshoppers, the larva) of Ijutterflies and moths, and the larvae of saw-flies ; and among the latter are butterflies, flies, bees, and bugs, while the larvae of most flies and bees do not possess mouth-parts homologous with those of the above.. STRUCTURE AND DEVELOPMENT OF INSECTS 27 Biting Mouth-parts. — insects are easih' seen in the grasshopper (Figs. 17 and IS). In brief, they consist of an upper and a lower lip, between which are two pairs of jaws which work transversely. The upper pair of jaws, or mandibles (7nd.), are stout, short, and horny, usually sharpened at the tip, slightly serrated at the margins, and j flattened at the base. The lower pair of jaws, or maxilhc (nix.), are longer, not so strong, and to each of them is at Mouth-parts typical of those of biting iG. 17. — Front -view face of grasshopper {Schizto- cerca americana): ant., antenna; oc, ocellus; eij., eye; cl., clypeus; Ibr., lahrum, or upper lip; w.r./).. maxillary palpus; Zah./)., labial pal- pus; gal., galea, lobe of maxilla; lab., labium, or under lip. tached an accessory lobe, and a jointed B hiip. Fig. 18. — .4, mouth-parts of grasshopper sep- arated to show posi- tion and relation; B, mouth-parts dissect- ed; Ihr., labrum; md., mandil)lc; hyp., hypopharynx or tongue; mx.p. Ih. p., labial palpus; lab., labium; max., maxilla}.. maxillary palpus; 28 INSECT PESTS OF FARM, GARDEN AND ORCHARD style called a palpus or feeler. At each side of the lower lip is another palpus, these palpi being sensory organs. Sucking Mouth-parts. — In the sucking insects these mouth-parts are prolonged into a tube through which the juices of the food plant — or animal — are sucked. In the plant-lice and other bugs the lower lip is elongated so that it forms a tube, and the maxillae and man- dibles consist of long hair-like bristles, or setse, enclosed within this tube (Fig. 20). The tip of this beak is rested upon the surface of a leaf into which the setse are thrust, lacerating the tissue, and by a pumping process of the mouth the juices are sucked up through the beak. The structure of the mouth- parts of the various orders of suck- ing insects varies considerably, but all agree in that they suck up the food in a liquid state. Any appli- cation of a poisonous spray to the surface of foliage will be of no avail parts of "a bug,' a sucking insect : against them, though sure death to a, seen from below, beak or ^^^^ biting insects which chew the rostrum {ro. G.) reposing be- n i • • ^ . ^ i tween forelegs; h, head removed : leaves. Suckmg msects must there- e, eye; Ihr., labrum; md., man- fore be killed by other means, dible-setse; rnx., maxillary setse; lah., labiimi. How Insects Breathe Along the side of a caterpillar or larva, on one thoracic seg- ment and on each abdominal segment except the last, is a small oval spot, in the centre of which is a slit closed by two mem- FiG. 19. — Cicada, showing mouth- STRUCTURE AND DEVELOPMENT OF INSECTS 29 Fig. 20. — Mouth-parts of a plant- louse: a, the jointed beak; h, the lancets, much enlarged ; c, antenna; d, foot. (After J. B. Smith.) Fig. 21 . — Diagram of tracheal or breathing system of an insect: sp., spiracles; tr., trachea. (After Kolbe.) Fig. 22. — Ideal section through an insect: a, aUmentary canal; h, heart; n, nerve cord; s, spiracle; t, tracheal tubes; I, legs; w, wings. (From Riverside Natural History.) 30 INSECT PESTS OF FARM, GARDj^N AND ORCHARD branous lips. These apertures arc called spiracles or stigmata (Fig. 21 sp.), and are the openings of the respiratory system. Similar openings are to be found in all insects, though not so easily seen in the adults. Connecting these spiracles is a pair of tubes on each side of the body, throughout its length, from which branch off smaller tubes to all of its organs and tissues. Fresh n. sp Fig. 23. — Internal anatomy of silk-worm, from photo of Azoux Model: A , upper or dorsal bodywall seen from within ; B, the back of the silk- worm removed, showing alimentary canal; C, alimentary canal removed, showing nervovis system and tracheal trunks; tr., trachea; d.v., dorsal vessel or heart; ph., pharynx or mouth; su., supra-oesophageal ganglion; sp.sp., spiracles or breathing pores; n., nerve cord; tr.t., tracheal trunk; oes., oesophagus or throat; cr., crop; s.g., silk gland; pro., provcntriculus ; st., stomach; h.i., hind intestine. air is thus inhaled to all parts of the body through these tubes (Fig. 21, tr). The l^lood of insects does not circulate through any system of tubes as it does in the higher animals. Along the middle of the back, above the alimentary canal, is a long tube popularly called the heart (Fig. 23, dv). This heart is composed of a number of chambers, each of which is furnished with side valves for admitting blood from the body-cavity. The blood coming into the heart from the body-cavity is propelled forward toward STRUCTURE AND DEVELOPMENT OF INSECTS 31 the head, where it again flows into the body-cavity. Thus various currents of blood are maintained throughout the body, but other than the heart there is no system of blood-vessels, the blood merely filling the body-cavity around and through the various organs and tissues. Constantly flowing around the respiratory tubes or trachea:^, the l)lood is quickly and thoroughly purified, though the exact manner in which this is done is not definitely known. The respiratory system has absolutely no connection with the mouth or pharynx (Fig. 23, ph), as have the lungs of the higher animals, and if an insect is to be suffocated, it must be done by closing the spiracles. It is in this way that tobacco-clust, lime, pyrethrum, and similar insecticides kill sucking insects, by penetrating the spiracles and choking the tracheal system. Whale-oil soap, kerosene emulsion, and the other " contact " insecticides, or " irri- tants," also stop up the spiracles and thus cause death, but they may act as " irritants," penetrating the skin and thus killing the insect. When insects are killed by means of a gas such as carbon bisulfide or h3'drocyanic acid gas, they are asphyxiated by a substitution of these gases for air, the same as are the higher animals. The ugh arsenical poisons are generally used as sprays for biting insects, soft-bodied caterpillars and similar larva? are often killed by the use of contact insecticides, which affect them the same as sucking insects. The reader will observe that, almost without exception, the remedies advised for different insect pests in the following pages are determined by some peculiarity^ either of structure or develop- ment, of the insect to be combated. CHAPTER IV FARM METHODS FOR THE CONTROL OF INSECTS The old adage " an ounce of prevention is worth a pound of cure/' is never more true than in the control of insect pests, for in almost all cases their successful control is by prevention before the injury has become acute, rather than by destruction after the injury is noticeable. Even insecticides must be applied so that they will kill the insect before it has done serious damage, for after damage is apparent it is too late to prevent the injury, so that the use of insecticides for the protection of crops must be of a pre- ventive nature. In the control of insects affecting the staple crops which are grown over immense areas with a small profit per acre, it is evidently impracticable to use insecticides and mechani- cal methods which are used in the orchard and garden. For the control of staple crop insects we are compelled to rely largely on general methods of farm management, which may be carried out in connection with the farm operations at small cost, and which will fatally interfere with the development of the insect to be con- trolled. To do this intelligently involves an understanding of the life-history of the insect, revealing the time at which it is most vulnerable and the reason for the method of control advised. The importance of such a knowledge of the life histories and habits of insects to be controlled by farm methods will become apparent in the following chapters. Though the insects affecting staple crops are more largely con- trolled by farm methods, those of the garden and orchard may be much reduced by the intelligent application of the same princi- ples, and he who adapts his methods so as to prevent insect attack will be much more successful than if he depends upon artificial means for their destruction. 32 FARM METHODS FOR THE CONTROL OF INSECTS 33 Looking Ahead. — In planning the management of their land and crops for the coming season, few farmers consider the effect which any given procedure will have upon the injurious insects with which they may have to contend. A field which has for several years been in wheat, corn, or tobacco, may be sown with some other crop for the sake of soil improvement, but how often is it considered necessary to rotate crops to avoid insect pests? In most cases they are left out of consideration vmtil a crop has been seriously injured and the necessity for a change of methods thus impressed on the owner. Particularly while crops are young they should be frequently inspected and examined for any evidence of the pests which com- monly affect them. Be prepared to attack any pests which may be found upon their first appearance, for many of the most destructive insects increase with amazing rapidity, and when they have become abundant it is too late to prevent the damage. Cwp Rotation. — One of the most important factors in insect control is the rotation of crops in such a manner that the same crop shall not be grown continuously on the same land. In many cases a yearly rotation will be advantageous, while a frequent rotation will always be found beneficial. Many insects feed on only one crop. It is evident, therefore, that if they hibernate in or near the field which it occupied and it is then planted to the same crop the next year, they will be furnished food for their increase, while if the field be planted in a crop not attacked by the insects peculiar to it, they will have to migrate from it, with probably a very considerable mortality as a consequence, for they, will radiate in all directions and many will die before finding food, while many more will have been destroyed in the preparation of the old field for the new crop. The western corn root-worm may be entirely controlled by a rotation so that corn is never grown two successive years on the same land; for the larvae feed only on the roots of corn, and when it is followed by a small grain, grass, or clover, they are starved out. Injury by the Hessian fly to wheat is also very materially 34 INSECT PESTS OF FARM, GARDEN AND ORCHARD reduced where a frequent rotation is practised, as is that of the chinch-bug on corn. Care should be exercised to arrange a rotation in which crops nearly related botanically do not follow each other, for usually the same insects attack them. Thus white grubs, cutworms, and wireworms live normally in grass land, and where it has not been plowed for several years they often become exceedingly abundant. If the sod be then turned under and the land planted to corn these insects will attack the corn, and as there are rela- tively few plants to the number of insects which were feeding upon the grass, the injury will usually be serious. To avoid this, sod land should be planted in a small grain, buckwheat, potatoes, or some crop not affected by these pests. Similarly, the insects which affect cabbage usually feed on all the cole crops, and turnips, radishes, etc., following cabbage will be liable to injury by the same pests. Clovers, cowpcas, and other leguminous crops become of importance in rotation in this connection, as they are not usually attacked by the insects affecting other crops, and of course are widely used in every good rotation for the pur- pose of storing nitrogen in the soil through their root tubercles. Time of Planting. — Planting crops so that they may avoid the greatest abundance of their worst insect enemies is often the best method for their protection. Thus late-sown wheat is usually exempt from the attack of the Hessian fly (see page 123) and late-planted corn is much less affected by the stalk-borer (see page 172) than that planted earlier. On the other hand early planting of early-maturing varieties often enables the crop to mature Ix'fore its pests become most aJjundant. Thus early planting and early varieties are of the greatest importance in preventing injury by the cotton boll weevil, the cotton boll- worm and corn ear-worm. Early cabbage plants seem to be less injured by root-maggots, and early varieties of peas escape the injury of the pea aphis. Weeds. — Many insects feed upon some common weed in one stage while in another stage they are injurious to a cultivated crop. Thus the flea-beetles feed upon the roots of solanaceous FARM METHODS FOR THE CONTROL OF INSECTS 35 weeds during the larval stage, while the adults attack all sorts of garden crops. In many cases caterpillars, such as the salt marsh caterpillar, army worms, the white-lined sphinx moth, and grasshoppers multiply upon weeds growing in neglected fields until they overflow and destroy crops. Many insects feed on weeds during the early part of the season or after the crop which they injure is harvested, so that the destruction of these weeds may often considerably shorten their breeding season or increase their mortality. Thus the corn root-aphis lives on the roots of smartweed and other weeds and grasses until corn is available and cutworms feed on whatever vegetation is found before a crop is planted. In this connection " volunteer " plants should be classed as weeds, as they frequently furnish food for insects in the same way. Thus the cotton boll weevil feeds on volunteer cotton in early spring and the Hessian fly on volunteer wheat in late summer and early fall. Such useless trees as wild cherry and seedling apple trees might also be considered as weeds, as they harbor many of the insect pests of our orchards and should be destroyed as far as possible. Fertilization and Culture. — Although there is some evidence that under some conditions, kainit, lime and nitrate of soda may have some direct effect on insects, it is probable that their chief importance is to so stimulate the plant that it will not be subject to insect attack or will grow in spite of some injury. It is well known that plants which have been weakened from any cause whatsoever are much more subject to the attacks of insects and diseases, and it is therefore obvious that plants which have had a vigorous growth and which will mature rapidly will much better withstand insect attack. Thorough preparation of the soil before planting, liberal fertilization, and thorough culture are most important in growing a crop in spite of its insect enemies. In many cases liberal fertilization and culture will mature a good crop where under poorer care it would have succumbed to insect injury. In general, land covered with barnyard manure presents more favorable conditions for the hibernation of insects than that fertilized with mineral fertilizers, but unless this is very appreciably Fig. 24. — Above, a poorly kept roadside with railfence overgrown with brambles, thus affording protection for large numbers of destructive insects during winter. Below, a well kept roadside, offering the least protection possible for destructive insects. (After Webster, U. S. Dept. Agr.), 36 FARM METHODS FOR THE CONTROL OF INSECTS 37 the case, it will usually be preferred to them as far as it is available. Clean Farming. — After a crop has been harvested there is usually some portion of the plant which is allowed to remain on the land. In this refuse the insects peculiar to the crop often feed and multiply until killing frost and then hibernate over winter, ensuring injury to similar crops on the same land the Fig. 25. — A field of cabbage stumps in midwinter, affording ideal condi- tions for the hibernation of cabbage pests. next year. Thus the wheat joint worm and the corn stalk-borer l>oth winter in the stubble of those crops, and the chinch-bug commonly hibernates in the butts of corn stalks, all of which may be largely controlled by burning the stubble. Possibly the most important means of control of the cotton bo-11 weevil is the destruction of the stalks in the fall as soon as the cotton can be picked, thus preventing the weevils feeding and starving them out l^efore they are ready to hibernate, and removing the shelter for hibernation. Thus all the remnants of a crop such as 38 INSECT PESTS OF FARM, GARDEN AND ORCHARD stubble, vines, leaves, or stumps, as may be, should be removed from the field as soon after it is harvested as possible. As many insects hibernate in such rubbish, this fact may sometimes be utilized by thoroughly cleaning a field and leaving one or two piles of rubbish in which man}' of the insects will assemble for hibernation, and which ma}* then be burned or otherwise destroyed. Many cabbage insects hibernate under the old stumps and leaves and will congregate in piles of them. The premises upon which the fence rows are kept free from weeds and grass and the fields are cleaned up antl plowed as soon as possible after a crop is removed, usually suffer much less from insect pests than thoo? of more easy-going neighbors. Burning. — Such cleaning up of stubble and of wild vegetation which furnishes food and shelter for insects may often be accom- plished bv burning. The burning over of grass land aids greatly in the control of army worms, chinch-bugs, grasshoppers and plant-lice, while the burning of the stubble will largely control the wheat jointworm. Strawberry beds are sometimes burned over in early spring to destroy the eggs of the root-louse, and aphides on small grains may sometimes be killed out on small areas by covering with straw and burning while the plants are small. Plowing. — Deep plowing and thorough harrowing are the most effective means of ridding the soil of many pests of staple crops. Late Fall Plowing. — Where the succession of crops permits, plowing in the late fall is most advantageous, as it destroys the insects Avhile hibernating, although for some insects , early fall plowing antl thorough harrowing during the fall are preferable. Where plowing is not possible, thorough disking is often used for the same purpose, as on alfalfa. As different insects pass the winter in different stages this method does not affect all alike. Some will be destroyed by having the cells in which they have gone to pass the winter broken up. and l3eing unable to construct new cells they will be subjected to undue freezing and thawing and excessive moisture, and will thus be killed by the weather. Cutworms and the corn stalk-borer pass the winter in the soil FARM METHODS FOR THE CONTROL OF INSECTS 39 as larvae; the cotton boll worm or corn ear- worm hibernates in the pupal stage; while May beetles and click beetles hibernate as newly transformed beetles; but all of them will be similarly affected by the breaking up of their winter cells, which is the most effective manner of combating them. Other insects lay their eggs in the ground in the fall which may be buried too deep for the young to emerge, or larvae or pupae which normally remain near the surface may be turned under so deeply as to destroy them. Thus grasshopper's eggs are laid in the fall just beneath the surface, and by plowing in late fall or early spring they may be turned under so that but few are able to emerge, which is the best means of combating them. The apple maggot hibernates in the pupal stage just beneath the surface of the soil, and by deep plowing in early spring the puparia may be buried too deeply for the flies to emerge. Young grasshoppers are often destroyed after they hatch by plowing deep furrows, starting at the outside of the field and plow- ing in a square, thus forcing them to the centre and catching large numbers of them in the furrows. Early plowing and thorough harrowing in the spring are of value against cutworms by keeping the ground fallow and thus starving them out before a crop is planted and the same method may be used against other pests with similar habits. Thorough cultivation in the summer has been found to be of value against many insects, affecting them differently according to their habits. Many which pupate in the soil during the summer are destroyed while making their pupal cells, or these cells are broken and they are thus subject to abnormal moisture and tem- perature conditions and are thus killed. This has been shown to be the case with the cotton bollworm or corn ear-worm, and is true of the plum curculio, against which thorough cultivation has proved to be one of the most effective means of control in apple orchards. Thorough cultivation is also of importance in breaking up the nests of ants which care for such aphides as the corn root- aphis. Summer fallowing is used to starve out some pests; for example, the clover root-borer may be eradicated by plowing up 40 INSECT PESTS OF FARM, GARDEN AND ORCHARD infested clover iinniecliately after it is cut and exjjosing the roots to the sun and wind, which will soon dry them out and thus destroy the food of the larvae, which will soon perish. Trap Crops. — Trap crops are those which are planted as a bait or lure to attract the early insects so that they may be destroyed upon them before the crop to be protected is available. Doubt- less the reason that trap crops are not more frequently used by the farmer is because their successful use requires more or less of a knowledge of the life history and habits of the pest to be fought. But that is easily acquired and will make the fight against them more interesting and successful. South of Mason and Dixon's line the harlequin cabbage- bug frequently becomes the most serious pest of cabbage and related plants. When a cabbage patch has become well infested it is an exceedingly difhcult matter to prevent injury, for the adult bugs cannot be killed by insecticides which will not injure the plant. If, however, a crop of kale be planted the previous fall, the bugs which hibernate over winter will attack it in the spring, and may then be killed by spraying them with pure kerosene, and the danger to the cabbage crop be thus largely averted. A few rows of wheat are often planted early in the fall as a trap for the Hessian fly, and as soon as the eggs are deposited they are plowed under deeply and the later planting thus at least partly protected. One of the most successful examples of averting injury ]jy a trap crop is the use of corn to lure the cotton bollworm and thus prevent its injury to cotton. Corn is the favorite food plant of this pest, which prefers to deposit its eggs on the silk and tassels. By planting a few strips of late-maturing corn through the cotton field, they will come into silk about the time the brood of moths which normally deposit their eggs on cotton are flying and they will lay them on the corn in preference, which should then be cut and fed to stock. In this way by planting strips composed of sev- eral rows planted at successive dates, the cotton may be almost entirely protected. Possibly a modification of this method may be applied for the protection of tomatoes or tobacco, though these FARM METHODS FOR THE CONTROL OF INSECTS 41 cro23s have never been thus protected from this insect to our knowledge. Radishes are sometimes used as a trap crop for the root-mag- gots which affect the roots of cabbages and onions. The same prhiciple is sometimes used in combating forest insects by gird- ling a tree upon which certain kinds of forest pests will concentrate, and it is then cut and burned. These examples will suffice to show that very many of the most important insect pests may be largely controlled by simply adapt- ing the general methods of farm management so as to avoid or prevent injury by them. They indicate the importance of a knowledge of the life history of any insect which is to be combated, knowing waiich, some of the above or similar methods will often suggest themselves as applicable. Such a control of insect life through the practical use of natural agencies epitomizes the scien- tific method in the art of agriculture; i.e., the most practical and effective and yet simple methods based upon exact knowledge.* * See F. M. Webster, Farm Practice in the Control of Field Crop Insects, Yearbook U. S. Dept. Agr., 1905, p. 465, and Some Things that the Grower of Cereal and Forage Crops Should Know about Insects, Yearbook U. S. Dept. Agr., 1908, page 367. CHAPTER V INSECTICIDES Materials used for the destruction of insects are commonly called insecticides, and are roughly divisible into four classes: 1. Poisons, which kill by being eaten and are usually composed of various forms of arsenic and are therefore often called arseni- cals. 2. Contact insecticides, which kill by either clogging up the spiracles, the openings of the respiratory system, or by entering the trachea, and thus causing suffocation, or by their corrosive action on the skin. 3. Repellants, which deter the insect from attacking the plant or animal to which they are applied. 4. Gases, which are used for fumigating buildings, stored prod- ucts and greenhouses where other means are not practicable. 1. Poisons Poisons are applied to the food of the insect and must be eaten by it to be effective. It is evident, therefore, that they are only effective against biting (mandibulate) insects, or for those which lap up their food from the surface, and that they are of no avail against the true sucking insects, such as the true bugs which suck the juices from beneath the surface of the plant. Poisons are not always, however, the most effective means of combating biting insects, which are sometimes more effectively controlled by con- tact insecticides or other means. Nearly all of the stomach poisons are derivatives of arsenic and are therefore termed arsenicals. As they are dangerous to human life they should be kept well labeled, locked up when not in use, and vessels in which they have been used should be care- fullv cleaned. 42 INSECTICIDES 43 1. Paris green is a green crystalline powder composed of the aceto-arsenite of copper. When properly made it should contain at least 50 per cent arsenic oxid (AS2O5), and there should be as little water-soluble arsenic as possible, for the water-soluble arsenic is the cause of the burning of foliage which often results from the use of Paris green. \'arious State laws require that there be not over 3J per cent soluble arsenic, but even this amount is often injurious to tender foliage. Paris green is rather a coarse powder and settles readily in water, and is readily washed off by drenching rains. It costs from 25 to 35 cents per pound. It is usually used at a rate of from 3 to 8 ounces to a 50-gallon barrel of water; 5 ounces per barrel is satisfactory for most purposes. In mixing, first stir up in a small vessel with a little water into a paste, which will mix more readily. Add an equal weight of quicklime, or slightly more will do no harm, which will take up any soluble arsenic. 2. London purple is a waste product in the manufacture of aniline dyes, and is principally arsenic and lime. It is quite variable in composition and usually contains a much higher, and quite variable, amount of soluble arsenic, so that it is apt to scald the foliage unless thoroughly mixed with fresh stone lime. For this reason it is now used only for rough work, such as poison- ing grasshoppers, making poisoned bran mash, etc., and is not to be recommended for general use on fruit trees and garden crops. It usually costs 10 or 12 cents a pound, and is used in the same proportions and in the same way as Paris green. 3. Arsenate of lead is usually sold in the form of a white paste, composed of arsenic and lead, the exact chemical composition varying with the process of manufacture. To be of standard grade it should contain at least 12^ per cent of arsenic oxid and not over f per cent water-soluble arsenic oxid (AS2O5), and not over 50 per cent water. Owing to the small amount of soluble arsenic it may be used in much larger quantities than other arsenicals and on tender foliage which others will injure. From 2 to 8 pounds per 50-gallon barrel of water are used, 2 or 3 pounds per barrel being commonly used for most of the 44 INSECT PESTS OF FARM, GARDEN AND ORCHARD pests of the orchard and garden. Arsenate of lead remains in suspension rather better than Paris green and is exceedingly adhesive, remaining on the foliage for two or three months. Arsenate of lead is made from arsenate of soda and acetate of lead or nitrate of lead, and may be made by the user if desired, but owing to the varying -composition of these chemicals when purchased on the open market and the fact that the manufactured article can now be purchased in quantity practically as cheap as it can be made, its home manufacture is not recommended, and is now but rarely practiced. The market price of arsenate of lead has varied widely, owing to strong competition, but usually sells at from 8 to 10 cents per pound in 100-pound kegs, and at 20 cents for single-pound packages. Arsenate of lead is now made in a powdered form for dusting on crops where spraying is impracticable or unsatisfactory. Most of that manufactured in powdered form is crystalline and will not mix as readily 'with water as the paste, and is therefore not recommended for use with water. One manufacturer, however, is producing an amorphous powder, which is bolted like flour, and which mixes readily with water, and may be used exactly the same as the paste, of course using approximately only half as much weight for the same effectiveness, as half of the paste is water. 4. Arsenite of lead is a compound very similar to the arsenate, which is made from sodium arsenite, but it contains less arsenic and usually much more soluble arsenic, for which reason its use has not proven satisfactory, and is rarely sold by reliable dealers. Used in Water. — The above arsenicals are generally diluted with water and applied as a spray, which is visually much the most efficient method. Where Bordeaux mixture or lime- sulfur is to be sprayed on fruit trees or garden crops for the control of fungous diseases, the arsenical may be added to them at the same rate as to water. The combination of arsenicals with other common fungicides is not usually possible without danger of serious injury to the foliage. Used as Dust. — Under some circumstances the arsenicals are more readily applied in the dust form. Dusting may l^e done INSECTICIDES 45 most effectively by the use of a powder-gun, which consists of a rotating fan which drives the poison from a reservoir through a tube by which it may be directed to the desired point. The powder-guns most commonly used are carried by a man, though larger machines carried on a wagon are in use for orchard work. Paris green is usually diluted with 10 to 20 parts of flour, ground gypsum, or preferably air-slaked lime, though some prefer to use it undiluted when machines are used which control the amount of the application. Dusting should be done while the dew is on the foliage in early morning, except on such plants as have a rough or adhesive foliage. Paris green is frequently used as a dust upon potatoes, cabbage and other garden crops, as well as for dusting weeds and grass for grasshoppers, army worms, etc. Powdered arsenate of lead has recently been shown to be an effective remedy for the cotton boll weevil (see page 272), and is used pure. Its use in dry form will doubtless be found more practicable on other crops than has that of Paris green. 5. Arsenite of lime is a home-made arsenical, very much cheaper than those previously mentioned, and giving very satisfactory results for certain purposes. It is not as adhesive as arsenate of lead, and as it sometimes burns foliage has been largely dis- carded for orchard spraying. It is, however, very satisfactory for potatoes and other low-growing crops, especially when added to Bordeaux mixture, which sticks it to the foliage, and it may be used to good advantage for fighting grasshoppers and leaf-eating caterpillars when it is desired to poison considerable areas of weeds or waste grass. The so-called Kedzie formula is the most satisfactory, as the soda hastens the complete combination of the arsenic, and the resulting solution is in a clear liquid form which can be readily measured.* Take 1 pound of white arsenic * Arsenite of lime is often made by boiling 1 pound of lime with 2 pounds of white arsenic in 1 gallon of water for thirty to forty-five minutes. This results in a paste of arsenite of lime, which settles in the solution. One quart of this mixture is used per barrel of water or Bordeaux mixture, but unless the stock solution is always stirred equally well, the amount of poison in a quart will be quite variable, with varying effectiveness; hence the clear solution of arsenite of soda as in the above formula is preferable. 46 INSECT PESTS OF FARM, GARDEN AND ORCHARD and 4 pounds of crystal salsoda (2 pounds only of anhydrous sal- soda are necessary) , and boil together in 1 gallon of water for twenty minutes. This forms a stock solution of arsenite of soda, whichmay be kept until needed. Put it in a jug and label " Poison." When ready to spray add a quart of this solution and 3 or 4 pounds of freshly slaked lime to each barrel of water (50 gallons) . When used at this rate the arsenite of lime will cost about 7 cents for a barrel, exclusive of lalDor in its preparation, as compared with 10 cents for an equal amount of Paris green (J lb.), or 20 cents for arsenite of lead (2 lbs.). Unless large quantities are to be used for the purposes indicated, it will hardly pay the small user to bother with its manufacture, and the danger of poisoning in the mixing or in the careless disposal of waste or uncleaned utensils must also be considered, though it may sometimes be useful in an emergency when manufactured arsenicals are not available. 6. Resifi-soap Sticker. — Upon the smooth foliage of such plants as cabbage and asparagus it is exceedingly difficult to stick Paris green or even arsenate of lead when used as a spray. To obviate this the addition of resin-soap acts as a sticker. Place 5 pounds of pulverized resin and 1 pint of fish-oil or any cheap animal oil, except tallow, in an iron kettle with 1 gallon of water, and heat until the resin is softened; add the lye solution as made for hard soap; stir thoroughly; add enough water to make 5 gallons and boil about two hours, or until the mixture will unite with cold water, making a clear, amber-colored liquid. If the mixture has boiled away too much, add sufficient water to make 5 gallons. This makes a stock solution of liquid resin soap. For use add three gallons to 50 gallons of water, and add 3 gal- lons of milk-of-lime or whitewash (3 lbs. stone lime in 3 gallons), and ^ pound of Paris green. The addition of lime turns the small soap particles into hard soap to which the Paris green adheres and is thus distributed throughout the mixture in uniform quantity and rendered exceedingly adhesive. The stock solution may be added directly to Bordeaux mixture with- out the addition of extra lime, to which Paris green or arsenate of lead may be added in the usual quantity. Similar resin soap, INSECTICIDES 47 called sticker, is sold by James Good of Philadelphia, Pa., and may be used in the same way at the rate of 3 pounds to 50 gallons. 7. Poisoned Bran Mash. — For combating grasshoppers and cut- worms arsenic is often applied in the form of a bran mash. Mix 1 pound of Paris green or London purple (or white arsenic col- ored with a dye) with 25 pounds of bran or middlings. Stir a quart or two of cheap molasses into a gallon of water and moisten the bran, stirring thoroughly, until it makes a stiff mash. Do not add so much water that the mash will be thin and will cake when exposed. Apply a heaping tablespoonful near each plant or every 2 or 3 feet in the row. Keep poultry out of fields thus treated. For cutworms apply a day or two before setting plants and as near evening as possible. 8. Hellebore. — The powdered roots of the white hellebore are often used as an insecticide in place of arsenicals, especially for currant worms, rose slugs, and similar saw-fly larvae and for insects affecting crops soon to be eaten, as the hellebore is much less poison to man and animals than arsenicals. It may be applied dry, diluted with from 5 to 10 parts of flour, or as a spray, 1 ounce to a gallon of water. It is too expensive to use except for a few plants in the yard or garden, and like pyrethrum, deteriorates with age and if exposed to the air. Harmlessness of Arsenicals when Properly Applied. — The ques- tion is frequently asked whether it is safe to apply arsenicals to vegetables and fruits to be used as food. Where sprayed or dusted as directed the amount of arsenic wdiich would be deposited on the plant would not be sufficient to cause any injury, and Professor C. P. Gillette has shown that twenty-eight cabbages dusted in the ordinary way would have to be eaten at one meal in order to pro- duce poisonous effects. Occasionally growers dust cabbage with an unreasonable amount of poison, and very rarely instances of poison- ing are recorded, but there is no value in applying any more poison than is necessary to make a thin film over the surface, and more than that is wasted. Because a certain amount of poison will kill an insect does not indicate that a larger amount can kill it any " deader." Experiments have also shown that tobacco sprayed as 48 INSECT PESTS OF FARM, GARDEN AND ORCHARD recommended cannot possibly bear enough arsenic to be injurious, and that cattle or horses may be pastured under trees sprayed with arsenicals with impunity.* 2. Contact Insecticides Contact insecticides are used against insects with sucking mouth-parts and soft-bodied biting insects, which may be more readily destroyed by this means than by arsenicals. These sub- stances arc fatal to the insect either by clogging the spiracles or trachea, and thus causing suffocation, or by corroding the skin. It should be remembered that the chitinous skin of most insects is not easily corroded, and that in most cases a material strong enough to penetrate the skin will also injure foliage, so that only soft-bodied insects can be combated with corrosive sub- stances upon foliage. In the application of contact insecticides it is absolutely essen- tial that the spray come into contact with the insect, as a mere spray- ing of the foliage is of no value whatever. 1. Kerosene emulsion is one of the oldest remedies for plant- lice, and other sucking and soft-bodied insects, and is often resorted to because it is readily made and the materials are always at hand. Dissolve h pound of hard or whale-oil soap (or 1 quart soft soap) in 1 gallon of ])oiling watei'. Add 2 gallons of kerosene and churn with a force pump In' pumping back and forth for five to ten minutes until the oil is thoroughly emulsified, forming a creamy mass with no drops of free oil visible. This stock solution is now diluted so that the resulting mixture will contain the de- sired per cent of kerosene. Thus for aphides one part of the stock solution should be diluted with from 10 to 15 parts of water, giving from 4 to 6 per cent of kerosene in the spray, while for a winter wash for San Jose scale, it should be diluted only three or four * This is not true of grass beneath trees which have Ijecn sprayed with a straight-jet fire-hose, as is commonly done in Massachusetts in the extensive operations against the gypsy moth, but refers to spraying which has been done with an ordinary spray nozzle, which ajoplies the material as a fine spray. INSECTICIDES 49 times, giving from IG to 22 per cent kerosene. The emulsion must l)e thoroughly churned and should be applied with a nozzle throw- ing a fine spray. Apply only enough to wet the insects. Equally effective emulsions may be made from crude petroleum, the pro- portion of the soap and crude oil in the stock emulsion varying with the quality of the oil. Emulsions made with some of the crude oils seem to be much less injurious to foliage of some plants than when made with kerosene. Such an emulsion is made in California from distillate oils and is known as distillate emulsion. AVe have used crude Texas oils with equal success. 2. Kerosene. — Pure kerosene should never be used on foliage, for though occasionally someone will report using it successfully without injur}', in practically all cases serious burning of the foliage results. It was formerly recommended against the San Jose scale on fruit trees, but such serious injury resulted that it has been almost entirely discarded, though it may be used on apple and pear trees if applied with a nozzle which throws a fine spra}', on a bright sunny day, and only a very thin film applied to the tree while it is dormant, but even these trees are often injured if the application is not made with the greatest care. 3. Crude Petroleum. — Crude petroleum is used in the same man- ner as kerosene against scale insects, but seems to be less injurious to the tree, and has been extensively used in New Jersey against the scale on peaches, where but little injury has resulted where it has been carefully applied. It contains more heavy oils and con- sequently does not penetrate the bark so readily, and the light oils evaporating leave the heavy oils on the bark for some months, which aid in preventing young scales from getting a foothold. Crude oil for use as an insecticide should have a specific gravity of from 43° to 45° Beaume scale, and is sold by certain Eastern com- panies as " insecticide oil." 4. Oil and Water Treatment. — Spray pumps have been sold for several years which make a mechanical mixture of oil and water in desired proportions. These have been thoroughly tested both by entomologists and by extensive use by practical fruit-growers and the general verdict is that they are unreliable and unsatisfac- 50 INSECT PESTS OF FARM, GARDEN AND ORCHARD tory. None of them now on the market give a uniform percentage of oil, and injury to foliage is therefore liable to result. With the advent of miscible oils the oil-and-water pump is not to be recom- mended. 5. Miscible Oils. During the last few years several manufac- turers have placed on the market under various trade names what are now called miscible oils. These are petroleum rendered solu- ble by the addition of vegetable oils, cut or saponified with an alkali, and are really a sort of liquid petroleum soap which will combine readily with water. They have been used principally as winter washes against the San Jose scale, for which they are most effective when diluted 10 or 12 times. For a summer wash they have been used effectively against plant-lice and other insects for which kerosene emulsion would be used, diluted 25 to 30 times. In barrel lots the miscible oils sell at 40 to 50 cents per gallon, thus making the cost of a gallon of mixture for a winter application at 10 per cent, 4 or 5 cents per gallon. 6. Whale-oil and Other Soaps. — Any good soap is an effective insecticide for destroying aphides and young or soft-bodied larva?. Any good laundry soap made into a thick solution one-half pound per gallon is an excellent remedy for such insects on house- plants. Whale-oil or fish-oil soap has been extensively used against scale insects and plant-lice. The best brands are made from caustic potash rather than caustic soda, and should contain not over 30 per cent of water, there being wide variation in the water content. For the pea aphis and other aphides 1 pound to 6 gallons of water has been found very effective. For a win- ter wash for the San Jose scale 2 pounds per gallon of water are applied while hot, the soap being dissolved in hot water. The soap can be bought for 3J to 4 cents a pound in large quantities, thus making the treatment for scale cost from 7 to 8 cents a gallon. 7. Lime-sulfur Wash. — The lime-siilfur wash has always been the standard remedy for the San Jose scale on the Pacific Coast, and during the last few years has come into wide use in the East for the same pest. It has also been found to be an efficient INSECTICIDES 51 remedy for the pear leaf blister-mite, and the oyster-shell bark-louse. In addition to its insecticidal properties it is an excellent fungicide, and the spring applications just before the buds start are very effective in killing out the wintering spores of various fungous diseases, while the diluted wash is being used as a summer spray for fungous diseases in place of Bordeaux mixture. The usual formula is, unslaked stone lime, 20 pounds; flowers (or flour) of sulfur, 15 pounds, water to make 50 gallons. Stir up enough water with the sulfur to make a thick paste. Slake the lime in the vessel in which it is to be cooked with a small quantity of hot water. Then add the sulfur paste to the slaking lime. Add 10 or 15 gallons of water and boil for forty-five min- utes. The mixture may then be diluted to make a barrel of 45 or 50 gallons, straining it carefully into the spray barrel or tank. A large iron kettle or hog-scalder may be used for boiling the wash, or where steam can be made available a steam pipe may be run into several barrels and the wash boiled in them. Such barrels may well be placed upon a platform so that the wash may be drawn from them directly into the spray-tank. The materials for making the wash will cost H to 1^ cents per gallon and the labor practically as much more. The leading manufac- turers and dealers in insecticides are now selling concentrated lime-sulfur solution which is all ready for use by merely diluting to the desired strength, at a rate which will make the solution to be used cost from 2^ to 3 cents per gallon, nearly as cheap as it can be made at home and with the saving of time and a dis- agreeable job. In many communities a central plant makes the wash and can sell it with a fair profit at a low rate. 8. Home-made Concentrated Lime-sulfur. — During the last few seasons many large growers have been making their own con- centrated lime-sulfur solution, and where the quantity to be used warrants, a considerable saving may be effected. The New York Agricultural Experiment Station has made very careful studies* of the best methods of making and diluting the mixture from which the following is quoted: *Bulletins 329 and 330, N. Y. (Geneva) Agricultural Experiment Station. 52 INSECT PESTS OF FARM, GARDEN AND ORCHARD Geneva Statiun Formula for Concexthated Lime-sulfuk Solution. r Pure CaO 36 lbs. Lime ] If 95 per cent pure. . ., 38 lbs. I If 90 per cent pure 40 lbs. Sulfur, high grade, finely divided 80 lbs. Water 50 gals. Dilutions for Dormant and Summer Spraying with Lime-sulfur Mixtures Reading on hydrometer. Amount of Dilution. Number of Gallons of Water to One Gallon of Lime-sulfur Solution. P"or San Jos^ Scale. For Blister -mite. For Summer Spray- ing of Apples. Degrees Beaumd. 36 9 81 8i ■8 7^ 7i 6! 6i 6 51 5i 5 4^ 4i 3! 3i 3 2^ 2i 2 12^ 12 lU 11 lOi 10 9^ 9' 8* 8 7i 7 6.V 6 5* 5 4! 41 4 3| 3\ 3 45 35 43 i 34 41+ 33 40 32 37 1 31 36i 30. 34i ?9 32 1 98 31 •^ 29+ '?6 27 1 25. 26 24 24i 23. 22f ?? 211 21. 19^ 20 18| 19 17 18 16 17. 15 18 14 15 12| " In making, slake the lime in about 10 gallons of hot water, adding the lumps of lime gradually to avoid too violent boiling and spilling over. . . . The sulfur must be thoroughly moistened and made into an even, fluid paste without lumps (before adding to the lime). . . . Pour in the sulfur paste gradually during the slaking, stirring constantly to prevent the formation of lumps, and when the slaking has finished add the full amount of water INSECTICIDES 53 and boil gently for one hour. If kettles and fire are used, more than the required amount of water may be used at first, to com- pensate for evaporation, or the volume ma}' be kept constant by adding successive small quantities to hold the mixture at the original level, as shown by a notch on a stick resting on the bot- tom of the kettle, and marked when the mixture first begins to boil. When boiling with live steam the mixture will be more likely to increase in volume than to decrease, so that no water need be adtled. " This concentrate will keep with little change, unless the weather is below 5° F., if stored in filled, stoppered barrels. Even in open receptacles there will be no loss if the surface be covered by a layer of oil to prevent access of air. Each boiling should be tested with a Beaume hydrometer * and its density marked on the barrels or other containers." The dilution is based upon the specific gravity as shown by the hydrometer and may be safely made according to the out- line in the above table. In making this mixture it is important that only high-grade, pure lime should be used, and lime with less than 90 per cent calcium oxid (CaO) should be discarded. 9. Self-boiled Lime-sulfur. — Self-boiled lime-sulfur has proven to be the only safe fungicide for the foliage diseases of the peach and stone fruits, and is used extensively as a summer spray on j)ome fruits. As a winter wash for San Jose scale it has not proven as effective as the boiled mixture, but when used as a summer spray for fungous diseases it also has considerable insecticidal value. Its general usefulness as a summer insecticide is in the process of experimental determination, l)ut sufficient results have already been secured to warrant the statement that it will prove of considerable value as a summer insecticide for certain pests, where it is to be used for the fungous diseases of the host plant at the same time. This mixture has been developed * These hydrometers, made specially for testing lime-suKur mixture, may be obtained from the Bausch & Lomb Optical Co., Rochester, N. Y., and other dealers in laboratory glassware. 54 INSECT PESTS OF FARM, GARDEN AND ORCHARD chiefly by the work of Mr. W. M. Scott of the United States. Department of Agriculture, from whose latest bulletin * the following is quoted : " In order to secure the best action from the lime, the mix- ture should be prepared in rather large quantities, at least enough for 200 gallons of spray, using 32 pounds of lime and 32 pounds of sulfur. The lime should Ijc placed in a Ixarrcl and enough water (about 6 gallons) poured on to almost cover it. As soon as the lime begins to slake the sulfur should be added, after first running it through a sieve to break up the lumps, if any are present. The mixture should be constantly stirred and more water (3 or 4 gallons) added as needed to form at first a thick paste and then gradually a thin paste. The lime will supply enough heat to boil the mixture several minutes. As soon as it is well slaked water should be added to cool the mixture and prevent further cooking. It is then ready to be strained into the spray tank, diluted, and applied. " The stage at which cold water should be poured on to stop the cooking varies with different limes. Some limes are so sluggish in slaking that it is difficult to obtain enough heat from them to cook the mixture at all, while other limes become intensely hot on slaking, and care must be taken not to allow the boiling to proceed too far. If the mixture is allowed to remain hot for fifteen or twenty minutes after the slaking is completed, the sulfur gradually goes into solution, combining with the lime to form sulfids, which are injurious to peach foliage. It is therefore very important, especially with hot lime, to cool the mixture quickly by adding a few buckets of water as soon as the lumps of lime have slaked down. The intense heat, violent boiling, and constant stirring result in a uniform mixture of finely divided sulfur and lime, with only a very small percentage of the sulfur in solution. It should be strained to take oub the coarse particles of lime, but the sulfur should be carefulh' worked through the strainer." 10. Sulfur. — Pure sulfur is one of the best remedies for red * Farmers' Bulletin, 440, U. S. Dept. of Agr., p. 34. INSECTICIDES 55 spider, on whatever plants it may occur, and for other mites which infest citrus fruits. It may be dusted on the infested plants or trees or applied with any other insecticide, using 1 or 2 pounds to 50 gallons. For citrus-mites the lye-sulfur wash and sulfide of lime are extensively used. Sulfur is frequently dusted in poultry houses to rid them of lice, and may be mixed with lard and rubbed on the skin of domestic animals affected with lice. 11. Pyrethrum, buhach, or Persian insect powder, is made by pulverizing the petals of the pyrethrum blossom, and kills insects by clogging their breathing pores. It is not poisonous to man or domestic animals and may therefore be used where other insecti- cides would be objectionable. It is chiefly used for household pests, and in greenhouses and small gardens. It deteriorates rapidly with age and should be kept in tight cans. An objection to much commonly bought is that it has been kept in stock too long b}' the retailer, thus losing its strength. Large users buy direct from the only American manufacturers, the Buhach Pro- ducing Co., Stockton, Cal. It may be used as a dry powder, pure or diluted with flour, or in water at the rate of 1 ounce to 2 gallons, which should stand a day before using. For immediate use it should be boiled in water for five or ten minutes. It is fre- quently Ijurnt in rooms to destroy mosquitoes and flies, for which it is effective, without leaving any odor after the room is aired.* 12. Tobacco. — A tobacco decoction may be made by boiling or steeping tobacco leaves, stems, and refuse in water at the rate of 1 pound to 1 or 2 gallons. This may be diluted slightly according to the strength of the tobacco and the insect to be combated. Such a decoction is an excellent remedy for dipping plants affected with aphides, and may be used as a spray for plant-lice and similar soft-bodied insects. Various extracts and solutions of tobacco are now sold by manufacturers which are extensively used in spraying against plant-lice, and which are proving more satisfactory on account of their uniform strength. Tobacco dust has been used successfully against root-infesting aphides by removing the sur- * See Farmers' Bulletin, 444, U. S. Dept. Agr., p. 7. 56 INSECT PESTS OF FARM, GARDEN AND ORCHARD face soil and applying a liberal dressing of the tlust and then covering. The rains leaching through the tobacco carry the tobacco water to the affected roots and destroy or repel the aphides. 3. Repellants Repellants include any substance which may be applied to a plant or animal to prevent insect attack. A popular notion that any vile-smelling substance will repel insect attack seems to have very little evidence in its support. Tobacco dust, air-slaked lime, or even fine road dust, thoroughly covering a plant will prevent the attack of various flea-beetles and leaf-eating beetles, but to be successful the plants must be frequently dusted and kept w^ell cov- ered. Bordeaux mixture, our most widely used fungicide, when liberally sprayed on potatoes and tomatoes, acts as a repellant to the little black flea-beetles which often seriously damage the young plants. The various fly-sprays which are used for spraying cattle to prevent the annoyance of flies act merely as repellants. Fruit-trees are often painted with a thick soap solution con- taining 1 pint of crude carbolic acid to 10 gallons as a repellant for the adult borers which lay their eggs on the bark. A substance which has come into prominence in the fight against the gypsy moth in New England is tree tanglefoot, a sticky substance the same as is used to coat fly-papers. This comes in the form of a very sticky paste, a band of which is placed around the trunk of the tree and which prevents the ascent of caterpillars, as it will remain sticky for some weeks. It may be used in the same way to prevent the wingless female canker worms and other wingless insects from ascending trees, or to prevent the ascent of caterpillars on unaffected trees. Various proprietary insecticides are frequently offered for sale with wonderful claims for their effect as repellants, but only in rare cases are they of any value except for use as a dust as already sug- gested. One of the most common fakes of this sort is that of the itinerant tree-doctor who offers to bore a hole in a tree and plug it with sulfur or other offensive compounds, which will effectively INSECTICIDES 57 prevent any insect or fungous depredations. A generous price per tree is charged, which is the only " effect " of the treatment. 4. Gases. Carbon Bisuljid (or disulfid) is extensively used against insects affecting stored goods and grains, and for root-feeding insects. It is a clear, volatile liquid giving off fumes heavier than air. It is sold in 25- to 100-pound cans at 10 to 12 cents per pound. It may be thrown directly onto grain without injury to it or placed in shallow dishes. For grain in store in fairl}- tight rooms apply 5 to S pounds to every 100 bushels, distril)uting the bisulfid over the surface or in pans containing not over one-half to 1 pound each. Make the enclosure as tight as possible; covering the grain with l)lankets or other tight cover, if necessary, and leave for twenty- four hours. Recent experiments have shown that the vapor is much less effective at low temperatures and that the dosage must be greatly increased at temperatures below 60° F. For fumi- gating buildings " there should be about 1 square foot of evap- orating surface to every 25 square feet of floor area, and each square foot of evaporating surface should receive from one-half to 1 pound of liquid." For fumigating clothing or household goods, place them in a tight trunk and place an ounce of liquid in a saucer just under the cover. The gas is exceedingly explosive; allow no fire or light of any kind around the building or enclosure until it has been well aired. The fumes should not be inhaled, for though not seriously poisonous, they have a suffocating effect and will soon produce dizziness and a consequent headache. The treatment for root-maggots and root-feeding aphides is discussed in connection with those insects (pages 355 and 496).* Hydrocyanic Acid Gas is extensively used for the fumigation of nursery trees and plants, certain greenhouse insects, pests of dwelling houses, storehouses, mills, etc., and in California for scale insects on fruit trees. It is made by combining cyanide of * For a complete discussion of the use of this gas, see Farmers' Bulletin, 145, U. S. Dept. Agr., and see page 197 below. Carbon tetrachloride is now used for some purposes in much the same manner as carbon bisulphide, and is not so explosive. 58 INSECT PESTS OF FARM, GARDEN AND ORCHARD potassium, sulfuric acid and water. The gas is slightly lighter than air and is a most deadly poison. Its use is to be recom- mended only by thoroughly competent and careful persons who are fully advised as to the method of use for the particular purpose desired. Concerning its use advice should be sought from the State Agricultural Experiment Station, or from the State Entomologist, or from the Bureau of Entomology of the U.S. Department of Agri- culture. The general methods used arc fully described by the late Professor W. G. Johnson in his l)ook '' Fumigation Methods \ (Orange Judd Co.), with which should be considered the results of more recent experiments and experience. Sulfur Dioxid. — The fumes of burning sulfur, mostly sulfur dioxid, have long been recognized as a standard remedy for the fumigation of dwellings and barracks for insect pests. Successful fumigation for the l^edl^ug has been reported when stick sulfur has been burned at the rate of 2 pounds per 1000 cubic feet of space. The chief objection is the strong bleaching effect of the fumes in presence of moisture and their destructive action on vegetation. Recently this gas has been extensively used under the name of '' Clayton gas," for the fumigation of ships and ships' cargoes, par- ticularly grain. It is forced into the tight hold of a ship by specia-l apparatus and is exceedingly penetrating and effective. The germinating power of seeds is quickly destroyed, but they are not injured for food. 1 to 5 per cent of the gas, with an exposure of twenty-four hours, is effective for most seed and grain pests. It cannot be used on vegetation or for moist fruits. Tobacco Fumes. — Tobacco is extensively used as a fumigant for aphides in greenhouses and for certain plants, such as melons, by using it under covers. Several forms are now commonly used. Tobacco or nicotine extracts are sold under various trade names, which are volatilized by heating either with a small lamp or by dropping hot irons into the dishes containing the fluid. The same material nisij be purchased in the form of paper w^hich has been saturated with the extract and which is burned accord- ing to directions, a certain amount being sufficient for so many cubic feet of space, which forms a more convenient method of INSECTICIDES 59 application. Certain finuly ground tobacco jjowders, called " fum'gating-kind " tobacco powder, are used in the same way and are much the cheapest form of tobacco for fumigation, though requiring slightly more work in preparing for fumigation. These tobacco preparations are excellent for the fumigation of household plants, which may be placed in a closet and then fumigated according to the directions of the particular brand employed. Melon vines, young apple trees, bush fruits, and similar outdoor crops may be effectively rid of plant-lice by fumigating with tobacco-paper under a frame covered with canvas or muslin sized with glue or linseed oil. For further discussion of Insecticides see Farmers' Bulletin 127, U. S. Qepartment of Agriculture- CHAPTER VI SPRAYING AND DUSTING APPARATUS Atomizers. — Hand atomizers of the general style shown in Fig. 26 may be purchased at any hardware store, and are useful for applying soap or oil solutions to a few house or garden plants. They are not adapted for more extensive use and to try to spray many plants, or a tree, with them, is a waste of time. Bucket Pumps. — The simplest type of spray pump is that made to use in a bucket. The better types usually cost $5 to $8, the cheaper styles, selling for $2 or $3, being inferior and unsatisfactory. Fig. 26. — An atomizer handy for spraying a few plants. There is as much difference in the structure of bucket pumps as in those of the barrel type, and many of the statements made below concerning the latter v.dll apply also to bucket pumps. The Ijuckct pump should have an air chamber, so that a steady pressure may l)e maintained. Some firms are making bucket pumps of the same general type of the barrel pump shown in Fig. 34, which are very satisfactory in this regard. A footrest attached to the pump and a clamp to attach the pump to the bucket are useful accessories, 60 SPRAYING AND DUSTING APPARATUS 61 Many firms arc now selling these pumps mounted in largo galvanizcd-iron covered buckets, and furnished with a mechanical agitator. This is a tlesirable arrangement, for the buckets are much larger than those ordinarily used, thus saving frequent filling, while the cover prevents slopping, and the pump is always ready for use without the necessity of hunting up a bucket and then cleaning it, which is necessary after using a bucket which is used for other purposes. Bucket pumps are useful for small gardens or for a few small trees, or bushes. Fig. 27. — a, a cheap type of bucket pump with no uir-chamber, which will not maintain satisfactory pressure; b, a better type of bucket pump with small air-chamber. (Courtesy Deming Co.) Knapsack Pumps. — The kiiapsack pump consists of a copper or galvanized-iron tank carried on the back like a knapsack, in which is mounted a bucket pump with a lever handle for pumping. In the better makes this handle is detachable, and a plain handle may be attached so that the tank may be used as a simple bucket pump, for which a footrest is attached to the tank. The pump should have a good mechanical agitator. The copper tanks are preferable, for Bordeaux mixture will soon eat through gal- vanized iron. Knapsack pumps are useful for spraying such 62 INSECT PESTS OF FARM, GARDEN AND ORCHARD crops as tomatoes, melons, etc., which cover the ground, so that it is difficult to drive through them without injuring the vines, crops growing on steep hillsides, or for a small acreage of any garden crops, small fruits, or small trees. The main objections to 1^*-^ "^^ them are that they are heavy to carry, thus limiting their use to a small area; they frequently slop over, and wet the carrier's back; and the pumps do not develop sufficient pressure for some kinds of work. Consequently they are not as much used as formerly, but are useful for the purposes indi- FiG. 28. — Bucket pump mounted in bucket, and mounted in tank v.ith agitator. (Covu-tesy Deming C'o.) Fig. 29. — Bucket pump with large air-chamber, which will maintain a good pressure. (Courtesy F. E. Myers & Bro.) cated, and inasmuch as they may also be used as a simple bucket pump, they are to be preferred to them. The cost varies from $8 to $12 or $15. Compressed-air Sprayers. — In recent j'ears the compressed- air sprayer has come into favor for use in small gardens. It consists of a brass tank which is filled with the liquid; the air SPRAYING AND DUSTING APPARATUS 63 is compressed by an air-pump, and spraying continues until the pressure runs down, when a stopcock is turned and the pressure is again raised by pump- ing. The tank holds from 3 to 5 gallons, and is carried beneath one arm, slung Ijy a strap over the other shouldei'. The chief ol)jections to this type are that it is not ver}' con- venient to fill, though the newer models are much improved, is not readily repaired, has no agitator, and recjuires frequent pumping. On the other hand, they are easily carried, do not leak, and leave both hands free, ^'f " ^O.-One of the best types of knapsack sprayers. Note foot- so that one might be used for rest, agitator, handle, and wide spraying a small tree from a step- "^"'^P'- (Deming Co.) ladder. These compressed-air sprayers cost from $5 to $8. Barrel Pumps. — The most serviceable spray pump for the average farm is the barrel pump. With a good barrel pump 100 to 150 full-grown apple trees may be sprayed in a day, so that it will be found sufficient for an or- chard of 500 trees or less. By using a row- spraying attachment, a few acres of pota- FiG. 31.— The knapsack sprayer in use. (Spramotor Co.) 64 INSECT PESTS OF FARM, GARDEN AND ORCHARD toes or other row crops may be sprayed with a Inirrel pump much more quickly than by hand. In buying a row attachment, be sure that it is adjustable for rows of different widths. A good barrel pump costs from $15 to $25. Most of the pumps sold 'at $10 or less are too light to do effective work or are not well constructed. Numerous pump companies advertise in the agricultural papers, and after considering the following points one may select a suitalile pump from their catalogs: Fig. 32.-t'ojn])iesyed- New type of compressed-air sprayer with air sprayer with separate pump. (E. C. Brown Co.) section of tank removed to show air pump within. 1. The pump should ])c guaranteed to furnish four nozzles at SO to 100 pounds' pi'cssure wnth ordinary pumping. 2. It should have a large air chamber within the barrel, and not projecting above it. 3. As few of the working parts of the pump as possible should be above the head of the barrel, as exposed parts are. easily broken. 4. The cylinder, plunger, valves and working parts should be of brass. The handles and other parts commonly made of cast iron are much more durable when made of malleable or galvanized iron. SPRAYING AND DUSTING APPARATUS 65 5. Tlierc should bo a good incchanical agitator of the paddle type, preferably arranged so that it can be worked with the pump handle without operating the pump. An agitator is essential to keeping the mixture in suspension. Agitators of the so-called " jet-type," in which a stream from the bottom of the Fig. 33. — An undesirable type of barrel sprayer — now off the market; the air-chamber and other parts above the barrel render it top-heavy, and may be easily broken. Fig. 34. — A desirable type of barrel pump embodying most of the features described. (Morrill & Morley.) cylinder is supposed to agitate the liquid, are unsatisfactory and allow a loss of pressure without sufficiently agitating the liquid. 6. The pump should be so attached to the barrel that it can be quickly removed for repairs. Those pumps which have lugs for attaching the pump plate to the barrel are much better than .those with screws. G6 INSECT PESTS OF FARM, GARDEN AND ORCHARD Fig. 35. — Two types of double-acting lever punipa, to be mounted on truck and connected with tank. Fig. 36 — Double-acting horizontal pump mounted on 250-gallon tank. A good type of outfit for medium sized commercial orchards. (Va. Agr. Exp. Sta.) SPRAYING AND DUSTING APPARATUS G7 8. The valves, with their seats or cages, should be readily removable for cleaning, and should be so constructed that they remain evenly ground. All of these points may not be embodied in any one pump, but most of the better pump manufacturers are embodying these features in their newer models, a good exampl*^ of which is shown in Fig. 34. Barrel, knapsack, and bucket pumps are manufac- tured which have separate tanks for oil and water which are mixed in a de- sired proportion and sprayed as a mechanical mixture. They have been found un- reliable in controlling the amount of oil, and are not now in general use. Horizontal Pumps. — For larger orchards and shade trees, the double-acting horizontal pumps which are operated with a lever, as shown in Fig. 35, furnish more power and conse- cjuently make more rapid work possible. They are mounted on 100- or 150- gallon tanks and may be arranged for filling the tank where running water is not available. These pumps cost from $30 to $50 and will maintain 100 to 125 pounds pressure with four to eight nozzles. They are usually used with two men spraying and another driving and pumping, or a fourth man pumps and changes places now and then with the driver, as the operation of this type is rather too heavy for one man constantly. Fig. 37. -Gasoline power sprayer, complete. Note wide tread steel wheels, steel tower on tank, and intake hose for filling tank where running water is not available ; 3 J h.p., 4-cycle gasoline engine, will main- tain 10 nozzles at 200 lbs. pressure. 68 INSECT PESTS OF FARM, GARDEN AND ORCHARD Fig. 38. — One of the latest three-cylinder power pumps, designed for spraying shade-trees and woodlands. FiGo 39. — Row-spraying attachment for use with barrel pump, adjustable for various width of rows. (Darning Co.) 1 SPRAYING AND DUSTING APPARATUS 69 Power Outfits. — For orchards of much over 500 trees or for extensive shade-tree work a gasoline power outfit is more econom- ical and enables a large area to be covered more quickly, which is often a most important consideration. Most of the pump manu- facturers and many gas engine companies are selling such outfits mounted upon a truck, with spray tank, and tower complete for from $250 to $400. Traction Sprayers. — For a small acreage of potatoes or other Fig. 40. — A good type of geared sprayer for row crops. row crops, a barrel pump with row attachment is very satisfac- tor}', but for any considerable acreage, a two-wheeled traction sprayer is much more economical of labor and time which are the two chief items in the cost of spraying. Such traction spraj^ers are made of widely different types, the power in all cases being furnished by a gear or chain which operates the pump from the wheels. The mechanical construction of the traction sprayers should be carefully studied, and if possible tested, before 70 INSECT PESTS OF FARM, GARDEN AND ORCHARD purchasing, as they differ greatly in efficiency. The better types cost from $60 to $100, and usually have attachments adapting them fcr all sorts of row crops, such as potatoes, strawberries, bush fruits, grapes, etc., which require different styles of piping to properly direct the nozzles. Several traction sprayers are sold for orchard work but, though they arc fairly satisfactory for small trees, they do not develop enough power for spraying large trees, and have a heav}^ draft. Gas ', after Forbes; fi, after Slingerland.)- - of crops in which land is not allowed to remain in grass for any length of time will prevent their increase. Many remedies have been suggested for these pests, but few of them have proved to have much merit in careful tests. Coating the seed with gas tar, as is done to protect it from crows, has been very widely practiced, and though previous experiments indicated that it could not be relied upon, Dr. H. T. Fernald conducted tests in Massa- chusetts in 1908 and 1909 in which seed coated wath • gas-tar and then dusted in a bucket of fine dust and Paris green suffi- cient to give the corn a greenish color, was effectively protected, the treatment seeming to act as a repellant, and not affecting the germination of the seed. 84 INSECT PESTS OF FARM, GARDEN AND ORCHARD Cutworms* Under the general term cutworms we commonly designate any of the larva of several species of moths, which are more or less similar in general appearance and hal^its, and which have the habit of feeding on low-growing vegetation, and cutting off the stem just at the surface of the ground. They should be carefully distinguished from white grubs, which are sometimes Fig. 52. — Earth removed from base of seedling to show cutworm in hiding — natural size. wrongly called cutworms on account of their similar habits. Some of the species attack certain crops more commonly than others, Init most of them arc quite omnivoi'ous in their feeding. When they become overabundant th('>' w\\\ cat an}'thing green and succulent — foliage, flowers, butls, fruit, stalks, or roots, and sometimes migrate to other fields in armies like the army worms. Some species commonly climl) young fruit trees which have been * "\'arious species of the family Noctuidce. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 85 planted on grassy land or which are allowed to grow in grass Fig. 53. — Greasy cutworm (Agrotis Fig. 54. — The dark-sided cut- ypsilon); o, larva; 6, head of same; worm (Agrotis messoria). c. adult — natural size. (After (After Riley.) Howard, U. S. Dept. Agr.) Fig. 55. — Pen'dromia saucia: a. adult, b. c, d, full-grown larva\- e, f, eggs all natural size except e, which is greatly enlarged. (After Howard, U. S. Dept. Agr.) or weeds, and are known as climbing cutworms. Our common species are most injurious to garden crops and to corn, cotton, 86 INSECT PESTS OF FARM, GARDEN AND ORCHARD tobacco and similar crops grown in hills or rows, small grains and forage crops being injured but rarely. Though over a score of species are common, it is not practica- ble to distinguish them in this discussion, and though their life histories are somewhat different, they may be considered as a class. The adults are moths with dark fore wings, variously marked with darker or lighter spots and narrow bands as shown in Figs. 52-59, and with lighter hind-wings, which are folded over the back when at rest. Like the cutworms, they feed at night, sipping the nectar from flowers, and are known as owlet moths. The females deposit their eggs in grass land or where a crop has been allowed to grow up in grass and weeds in late Fig. 56. — The bronzed cutworm (Nephelodes minians Guen.) : back and side views of larva — enlarged, and moth — natural size. (After Forbes.) summer, laying them in patches on the stems or leaves of grasses or weeds, or on stones or twigs in such places. The little caterpillars which hatch from these eggs in August and September feed on the roots of whatever vegetation is available until frost, going deeper as it approaches, and finally hollow out small cells, in which they curl up and hibernate until the next spring. The next spring they are exceedingly hungry after their long fast, and attack any vegetaton at hand with surprising vorac- ity. If the land is in grass or weeds they have plenty of food, and if it is then plowed and planted in some crop, it will certainly be injured. The cutworms usually become full grown during late spring or early summer, and are then about 1^ to 2 inches long, of a dull l)rown, gray or blackish color, often tinged with green- INSECTS AFFECTING GRAINS, GRASSES, FORAGE 87 ish, and more or less marked with longitudinal stripes, oblique dots antl dashes, the markings usually being of a subdued tone, so that the cutworm harmonizes in color with the soil. They are cylindrical, with the head and prothoracic plate horny and reddish brown, and bear three pairs of jointed leo-s Fig. 57. — Cutworm moths: b, the well-marked cutworm-moth {Noctva clandestina Harris); the dingy cutworm {Feltia subgothica Haworth); male (w) and female (/) moths. (After Slingerland.) on the thorax and five pairs of prolegs on the abdomen. The mature caterpillars pupate in cells a few inches below the sur- face and in three or four weeks the adult moths emerge, usually in July and early August in the Central and Northern States and earlier farther south. Thus there is usually but one generation a year in the Xorth while in the South there are commonly two generations and in some cases three. Though other stages than the larvte of various species are known to sometimes hibernate, nevertheless 88 INSECT PESTS OF FARM, GARDEN AND ORCHARD the worst injury is usually done in the ; pring, when young plants have just been set or are just appearing. Control. — It is evident from their life history that like the white grubs and wireworms, cutworms may be most effectually combated by plowing in late fall and again plowing and har- rowing thoroughly in early spring, so as to keep the land fallow and thus starve them out. Land which is to be planted in corn or crops subject to cutworm injury should be plowed as early as possible in late summer of the preceding year and kept fallow so that the moths will not deposit their eggs upon it, as they will if it is left in grass or weeds. Fig. 58. — Moth of the glassy cut- Fig. 5!). — Granulated cut-worm {Agrotis an- worm {Hadena devastatrix nexa). a, larva; /, pupa; h. adult — natural Brace). (After Forbes.) size. (After Howard, U. S. Dept. Agr.) Poisoned bran mash (see p. 47) is proljaljly the best thing for destroying cutworms, and if well applied a few days before plants are set or a few days after seed is planted, will often protect crops on infested land. On corn land it may be applied with a seed drill, and in gardens an onion drill is sometimes used in the same way, placing the mash on the sui'face near the plants; or it may be applied by hand, placing a tablespoonful near each plant or every 2 or 3 feet in the row. Distribute the mash late in the afternoon, so that it will still be moist when the worms feed at dusk. Keep poultry away from fields so treated. Clover which has been thoroughly sprayed or clipped in water containing one-third pound Paris green per barrel may be used in the same way, particularly along the outside of fields to be protected from invasion or along borders of fields next to grass. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 89 Market gardeners frequent!}' protect cabbage, tomato and similar plants by knocking the bottoms out of tin cans or making cylinders of building paper and placing these around the stems, sinking them into the soil. Where cutworms assume the climbing habit and attack fruit trees, distribute the bran mash or poisoned clover liberally around the bases of the trees and put a band of tanglefoot around the trunk of each tree, which will prevent their ascent. Thorough cultivation of the orchard and neighbor- ing land will also reduce their numbers. When they assume the migratory habits of army worms, they may be controlled by the same methods as described for them. Garden plants may some- times he protected from cutworms, as well as flea beetles, by dip- ping them in arsenate of lead, 3 pounds per barrel, when planting. The Chinch-bug * The adult Chinch-bug is al)out one-fifth inch long, with a black body. Its white wings lie folded over each other on the abdomen, and arc marked l)y a small black triangle on their outer margins, while the bases of the antennae and the legs are red. The young bugs are yellowish or bright red marked with l)rownish-l3lack, l^ecoming darker as they grow older. Along the Atlantic coast and along the southern shores of the Great Lakes north of a line from Pittsburg, Pa., to Toledo, Ohio, the majority of the adults have short wings reaching but half over the abdomen and are incapable of flight; but between the Alleghany and Rocky Mountains the long- winged form greatly predominates. It occurs also in restricted localities in Central America and along the Pacific coast. The worst injury is to small grains and corn in the Central and North Central States, but frequently injury is done in the Eastern States, especially to timothy meadows which have stood for several years. Though individually insig- nificant, when assembled in countless myriads chinch-bugs have doubtless been of greater injury to tlie farmers of the Mississippi Valle}' than any other insect attacking grain crops, the total damage from 1850 to 1909 being estimated at $350,000,000.t * Blissus leucopierus Say. Family Lygoeidoe. t See Circular 113, Bureau Entomology, U. S. Dept. Agr., F. M. Webster. 90 INSECT PESTS OF FARM, GARDEN AND ORCHARD Life History. — During the winter the bugs hibernate in clumps of grass, in the butts, and in old shocks of corn, or under what- ever rubbish is available. In early spring they assemble in fields of grass and small grains. Soon they pair and the females commence to lay their small yellowish-white eggs upon the roots or bases of the stalks, each laying some 150 to 200 eggs. The eggs are laid from the middle of April until the first of June, depending upon the latitude and weather, and hatch in two or three weeks. As the nymphs grow they often do serious injury to small grains and grass, upon which they become full grown about the time of harvest. When wheat is harvested they spread to oats and soon to corn, but, curiously enough, though P'lG. 60. — The chinch-bug {Blissus leucopterus Say): adult at left; a, b, eggs magnified and natural size; c, young nymph; e, second stage of nymph; /, third stage ; <;, full-grown nymph or pupa ; d, h, i,\egs; i, beak through which the bug sucks its food. (After Riley.) the adults have wings they travel from field to field on foot, were it not for which fact we should be at a loss to cope with their migra- tion. Eggs are now laid upon the unfolding leaves of the corn, from which the nymphs commence to emerge in about ten days. This second brood matures on corn in August and September and is the one which later hibernates over winter, though where corn is not available the whole season may be passed on grass. Control. — The burning over of grass land, and the grass along fences, hedges, and roads, as soon as it becomes dry enough in late fall and early winter, is of prime importance to destroy the bugs after they have gone into hibernation. The removal INSECTS AFFECTING GRAINS, GRASSES, FORAGE 91 of all corn stalks from the fields and plowing the butts under deeply, or where th€ bugs are very abundant, raking out the butts and burning them, will rid the fields of the pest. It is practically impossible to combat the pest in the summer Fig. 61. — Corn-plant two feet tall infested with chinch-bugs. (After Webster, U. S. Dept. Agr.) on grass or small grains, but its migration to corn or from field to field may be effectually checked. In dry weather a dust furrow may be used as a barrier to good advantage. Just before harvest plow a deep furrow around the field to be protected, or on the threatened sides, and thoroughly pulverize the soil by dragging a heavy log back and forth in the furrow, making 92 INSECT PESTS OF FARM, GARDEN AND ORCHARD the side next the corn as steep as possible.* In attempting to climb this barrier, the dust will slide from under the bugs and large numbers will accumulate in the bottom of the furrow, where they will be killed by the heat of the soil if it has a temperature from 110° to 120° (air temperature of over 90°). Keep the furrow clean by dragging a log through it now and then. By sinking post-holes a foot deep every few feet in the bottom of the furrow the bugs will collect in them and may be crushed or killed with kerosene. Such a dust furrow will be of no value in showery weather, and is most effective in hot dry weather on light soil; it may often be used to advantage in combination with the following methods. In place of the dust furrow or in com])ination with it, a strip of coaltar is often run around the field. The strip should be about the size of one's fingei-, which can be made l)y pouring from a watering can with the mouth stopped down, and shoukl be run inside the dust furrow and with post-holes sunk along its outer edge. Sometimes it is run in a zig-zag Hne with the holes at the inner angles so that the bugs will be concentrated at the holeg. These tar strips must be freshened whenever dust or rubbish covers them. The soil may be prepared for the tar strip ]3y plowing a back furrow and packing the top with a roller or beating it hard with spades; or a strip of sod may be prepared by scraping away the grass with a farm scraper and then smoothing carefully with .shovels or hoes; or a dead furrow may be run and the tar strip run on the smooth bottom. To maintain such a tar strip for four weeks costs about $2 a mile and has proven itself entirely practical and effective. If the bugs have already become numerous in the outer rows of corn, most of them may be destroyed by spraying with kerosene emulsion (see p. 4S) made to contain four per cent kerosene, apply- ing it in the early morning or towards night. It costs 34 cents a * Such a furrow may possibly be made more readily by plowing several furrows and harrowing the ground thoroughly until reduced to a fine mulch and then plowing a dead furrow through the middle, and then dragging this with a log, making the sides as steep as possible. With such construction the furrow will cost about three cents per linear rod. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 93 barrel dilutctl, and a man will spra}- five acres per day, using a barrel per acre. Whale-oil soap, one-half pound to the gallon of water, has proven equally effective and cost $1.12 per barrel. A blast torch, for which an attachment is furnished with many of the compressed-air spraj'ers, may be used to advantage for destroying the Ijugs in a dust furrow or along the tar line, or a spray of pure kerosene or crude petroleum may be used for the same purpose. Extensive experiments have been made in Illinois and Kansas with the use of the muscardine fungus against the chinch-l)ug. Though occasionally the residts seem to ho profitable, and though it is undoul)tedly effective in wet seasons and it may be well to distribute the fungus to places where it does not occur so that it may reduce the numbers of the bugs in wet seasons, it seems to be of very little value in dry seasons, when the injury is worst, and cannot l)e relied upon to check the increase of the pest when used according to the methods so far devised. When chinch-bugs Ijccome abundant and their migration to corn seems imminent, the farmer should prepare to devote himself and as numy hands as necessary to fighting them until their advance is checked, for delay will mean ruin, while the prompt use of the above methods will save the corn crop. Grasshoppers or Locusts * Plagues of destructive locusts — or what we Americans call grasshoppers — have been recorded since the dawn of history. In America the worst devastation was done by the flights of the Rocky Mountain or Migratory Locust {Melanoplus sprefus Thos.), w^hich swooped down upon the States of the western part of the Mississippi Valley in the years 1873 to 1S76 in destruc- tive clouds. Concerning their recent distribution, numbers, and dcstruc- tiveness, Mr. W. D. Hunter reported after the season of 1897: " There was, this season, a general activity of this species through- out the permanent breeding region greater than at any time in * Various species of the family Acrididoe. 94 INSECT PESTS OF FARM, GARDEN AND ORCHARD many years. This was brought about by a series of dry years, which have resulted in the abandonment of farms in many places. It is, of course, well understood that the absence of serious damage since 1S76 has been partially due to the settUng up of valleys in the permanent region. 1 wish to make it clear, however, that the dryness is the primary and the abandoning a secondary cause." " Serious injury has occasionally been done in restricted locahties in Minnesota, the Dakotas, Montana, and Manitoba, but in recent years it has been difficult to find the species except in the mountains, and it will probably never again be a plague in the Central States." The Rocky Mountain Locust Let us first consider the species which has been the most injurious, as the other locusts differ from it in but few essential points other than in being non-migratory. To correctly understand its habits the reader should first divide the area which this species affected into three parts. Of these the (1) Permanent Region, which included the highlands of Montana, Wyoming, and Colorado, formed the native breeding- grounds, where the species was always found in greater or less abundance ;* (2) the Subpermanent Region, which included Man- itoba, the Dakotas, and western Kansas, was frequently invaded; here the species might perpetuate itself for several years, but disappeared from it in time; (3) the Temporary Region, which included the States bordering the Mississippi River on the west, was that only periodically visited and from which the species generally disappeared within a year. Spread. — When for various reasons the locusts became excess- ively abundant in the Permanent Region they spread to the Subpermanent Region, and from there migrated to the Tem- porary feeding-grounds. It was the latter area which suffered most severely from their attacks, but, fortunately, they did not do serious injury the next A'ear after a general migration. In the Subpermanent Region their injuries were more frequent than in the Temporary, but were hardly as severe or sudden as * Bull. 25, U. S. Dept. Agr., Div. Entomology. C. V. Riley. INSECTS AFFECTING GRAINS. GRASSES, FORAGE 95 farther east. Migrating from their native haunts, flights of the grasshoppers usually reached southern Dakota in early sum- mer, Colorado, Nebraska, Minnesota, Iowa, and western Kansas during midsummer, and southeastern Kansas and Missouri during late summer, appearing at Dallas, Texas, in 1874, and about the middle of October, and even later in 1S76. As thus indi- cated, the flights were in a general south to southeasterly direction, while west of the Rockies they descended to the more fertile valleys and plains, but without any such regularity as eastw^ard. While the rate of these flights was variable and entirely dependent upon local weather conditions, twenty miles' per day was con- sidered a fair average. The flights were more rapid and more distance was covered in the early part of the season, when, while Fig. 62. — Rocky Mountain locust; adult and different stages of growth of young. (After Riley.) crossing the dry prairies, a good wind often enabled them to cover 200 to 300 miles in a day. As they first commenced to alight in their new feeding-grounds their stay was limited to but two or three da3's, but later in the season it was considerably lengthened, and, after a section was once infested, swarms were seen to be constantly rising and dropping during the middle of the day. Life History. — Over all the infested area, and while still sweep- ing it bare of crops and vegetation, the females commence to lay their eggs, and continue to deposit them from the middle of August until frost. For this purpose " bare sandy places, especially on high, diy ground, which is tolerably compact and not loose," are preferred. "Meadows and pastures where the grass is closely grazed are much used, while moist or wet ground is generally avoided." In such places the female deposits her eggs in masses of about thirty. These are placed about an inch below the surface in ft pod-like cavity, which is lined and the eggs are covered by a 96 INSECT PESTS OF FARM, GARDEN AND ORCHARD mucous fluid excreted during oviposition. From two to five hours are required for this operation, and an average of three of these masses is deposited during a period of from six to eight weeks. As the time of ovipositing varies with the latitude, so the hatching of the eggs occurs from the middle or last of March in Texas till the middle of May or first of June in Minnesota and Manitoba. Until after the molt of the first skin, and often till after the second or third molt, the young nymphs are con- tent to feed in the immediate vicinity of their birth. When the food becomes scarce they congregate together and in Fig. 63. — Rocky Mountain locusts: a, a, a, females in different positions, ovipositing; h, egg-pod extracted from ground, with end broken open; c, a few eggs lying loose on ground ; d, e, show the earth partially removed, to illustrate an egg-mass already in place and one being placed; /shows where such an egg-mass has been covered up. (After Riley.) solid bodies, sometimes as much as a mile wide, march across the country, devouring every green crop and weed as they go. During cold or damp weather and at night they collect under rubbish, in stools of grass, etc., and at such times almost seem to have disappeared; but a few hours of sunshine brings theni forth, as voracious as ever. When, on account of the immense numbers assembled together, it becomes impossible for all to obtain green food, the unfortunate ones first clean out the underbrush and then feed upon the dead leaves and bark of timber lands, and have often been known to gnaw fences and INSECTS AFFECTING GRAINS, GRASSES, FORAGE 97 frame buildings. Stories of their incredible appetites are legion; a friend informs me that he still possesses a rawhide whip which they had quite noticeably gnawed in a single night! l^y mathematical computation it has been shown that such a swarm could not reach a point over thirty miles from its birthplace, and as a matter of fact they have never been known to proceed over ten miles. Fig. 64. — A swarm of grasshoppers attacking a wheat-field. (After Riley.) As the nymphs become full grown they are increasingly subject to the attacks of prcdaccous birds and insects, insect parasites, fungous and l^acterial diseases, and are also largely reduced ])y the canniljalistic appetites of their own numl^ers. When the mature nymphs transform to adult grasshoppers and thus become winged, large swarms are seen rising from the fields and flying toward their native home in the Northwest. 98 INSECT PESTS OF FARM, GARDEN AND ORCHARD This usually takes place during June and early July in the North, and as early as April in Texas, so that it is frequently impossible to distinguish the broods of the temporary region from the incoming brood which has migrated from the permanent region. Although the eggs for a second brood are sometimes laid, these seldom come to maturity, and the species is essen- tially single-brooded. The Lesser Migratory Locust Besides the Rocky Mountain locust there is only one other species that truly possesses the habit of migrating, though to a far lesser extent, and which is therefore known as the Lesser Migratory Locust (Melanoplus atlaniis Riley). It is considerably smaller than its western relative and somewhat resembles the red-legged locust both in size and appearance. The species is very widely distributed, occurring from Florida to the Arctic Circle east of the Mississippi, and on the Pacific slope north of the fortieth parallel to the Yukon. The habits and life history of the species are in all essentials practically the same as the former species, except that they have no particular breeding- grounds. Injuries by this grasshopper were first noticed in 1743, almost seventy-five years before the first record of the Rocky Mountain locust, and since then it has done more or less serious damage in some part of the territory inhabited every few years. Non-migratory Locusts There are several species of locusts which, though lacking the migratory habit, and thus being more easily controlled, often become so numerous as to do serious damage over limited areas. Both as regards the regions inhabited, its habits, and life history, the common Red-legged Locust {Melanoplus femur- ruhrum Har.) hardly differs from the last species, and is often found in company with it. It is non-migratory, however, and though the damage it does is thus entirely local, it is often of considerable importance. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 99 Fig. 65. — Red-legged locu.'^t (Melanoplus femur - rubritm Harr.). (After Riley.) Records of locust plagues in California date back as far as 1722. Many of them were doubtless due to the California Devastating Locust {Melanoplus devastator Scud.), and in the last invasion of 1885 this species outnumbered all others seven to one. Resembling the last two species in size and markings, the habits and life history of this species are also supposed to be similar to them, though they have not as yet been thoroughly studied. Together with the last species the Pellucid Locust (Caninida pellueida Scud.) has been largely responsible for the losses occa- sioned by locusts in California, and has also l)een found in New England, but is not noted there as specially destructive. Our largest winged Amer- ican locust, the American Acridium (Schistocerca ameri- cana Scud.), is practically confined to the Southern States from the District of Columbia to Texas, and thence south through Mexico and Central America, being rarely found in the North. This species is essentially a tropical r.^ ao ^u 11 •] 1 "^^ /^^ 1 one, and has often been ex- riG. 6G. — Ihe pellucid locu.st {Camnula \ . pellueida 'S>Q,\id.). (After Emerton.) ceedingly destructive, being especially so in 1876 in ]\Iissouri, Tennessee, North Carolina, Georgia, and southern Ohio. Considerably larger than the preceding species are the Dif- ferential Locust (Melanoplus differentialis Thos.) and the Two- striped Locust (Melanoplus hivittaius Scud.), of which the former is peculiar to the central States of the Mississippi Valley, Texas, New Mexico, and California, while the latter has a more extended range from Maine to Utah and as far south as Carolina and 100 INSECT PESTS OF FARM, GARDEN AND ORCHARD Texas. These two differ from the smaller species in laying only one or two masses of eggs, and the eggs of differentialis Fig. 67. — The American acridium {Schistocerca americana Scud.), (.\fter Riley.) have often been found placed under the bai'k of logs, but other- wise their habits are very similar. The two-striped locust is characterized by two yel- lowish stripes extending from the eyes along, the sides of the head and thorax to the extremities of the wing-covers, and Fig. 68.-The Two-striped locust (Mela- '' P'°^^^^>^ ^^'^ ^P^"'' nophis bivittatus Scud.). (After Riley.) ^OSt commonly observed by the farmer. The Differential Locust. — Throughout the Mississippi Valley from Illinois southward, the Differential Locust * is one of the Fig. 69. — The Differential locust (Melanoplus differentialis Thos.). (After Riley.) most common and destructive grasshoppers, and is an excellent example of several of our more abundant and injurious species which have very similar habits. * Melanoplus differentialis Thos. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 101 " The little grasshoppers hatch about the middle of May, from eggs which were laid in the fall, though we have observed them in March in Central Texas, and are of a dusky brown Fig. 70. — The southern lubber grasshopper {Dictyophorus reticulatus) : nymph^ and adult, slightly enlarged. Lolor, marked with yellow. The head and legs are the most prominent feature of the young nymphs. During their subse- ([uent growth they molt five times at intervals of ten days to two weeks, the relative size and appearance of the different stages being shown in Fig. 72. Professor H. A, Morgan, who made a careful study of an outbreak Fig. 71.— Egg-mass of the . . differential locust — enlarged. of this species m Mississippi m 1900, has given an interesting account of their growth and habits. " The young on first emerging from the eggs are sordid white and after an airing of an hour or two, are darker, assuming 102 INSECT PESTS OF FARM, GARDEN AND ORCHARD Fig. 72. — Nymphs of the differential locust in different stages (1 to 5) of growth — all enlarged. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 103 a color not unlike the dark-gra}' alluvial soil over which they feetl. There are changes of color as the earlier stages are assumed, but until the close of the third stage these changes are not readily perceptible in the field to the naked eye. At tlie close of stage four the greenish yellow color becomes prominent on many forms, and in stage five the greenish yellow and yellow brown colors predominate. The vigorous feeding and rapid growth of the young in stages four and five, and the promi- nence of the wing-pads in stage five, cause the grasshoppers in these conditions to appear almost as conspicuous as adults. '' The habits of the young are interesting, and a knowledge of some of them may be helpful in developing remedies. After hatching they remain for several hours in close proximity to the egg-pod from which they emerged. With this period of faint-heartedness over, they may venture out for a few yards each day into the grass, weeds, or crop neighboring the egg-area. Upon being disturbed they invariably make the effort to hop in the cHrection of the so-called nest. Nymphs emerging from eggs on a ditch bank, if forced into the water, will seldom make the effort to reach the other side, but will turn back to the bank from which they were driven. As development takes place the extent of their peregrinations into the crop is easily traced by the shot-hole appearance of the leaves upon which they feed. The tender leaves of cocklebur are always preferred by the grasshoppers in the early stages. Young Bermuda grass is also a favorite food, and succulent grasses of all kinds are freely eaten. In the third, fourth, and fifth stages, as grass, weeds, and even shrubs disappear along the ditch banks and bayous, the crops of corn and cotton adjacent begin to show signs of vigorous attack, and the march of destruction commences. ... A few hours before molting the grasshoppers tend to congregate and become sluggish. Molting varies as to time, and slightly as to manner, with different stages. In the early stages less time is required and the operation occurs on the ground or upon low bunches of grass and weeds. Every effort of the grass- hoppers at this time seems to be to avoid ccnspicuity, and in 104 INSECT PESTS OF FARM, GARDEN AND ORCHARD doing so spare themselves, in a manner, enmity of parasites. After the molting of the first, second, and third stages it is not long before the young grasshoppers are sufficiently hardened to begin feeding again, but after the molt of the fourth and fifth stages, particularly the last molt, some time is required to extend the wings and dry and harden the body before feeding is resumed. The last molt usually occurs on the upper and well-exposed leaves of corn and other plants upon w^hich they may be feeding, though it is not uncommon for the grasshoppers to drop to the ground during the maneuvers of the process. The reason for the selection of the more exposed leaves for the last molt is obvious. The bodies are large, and rapid drying protects them from fungous diseases which lurk in the more shaded and moist sections during the months of June and July. The last prominent habit to which we call at- tention is that of the fully grown grasshopper-6 to seek the shade offered by the growing plants during the hottest part of the day." The hoppers become full grown about the first of July. The adult is about IJ inches long, its wings expand 2^ inches, and it is of a bright yellowish-green color. The head and thorax are olive-brown, and the front wings are of much the same color, without other markings, but with a brownish shade at the base; Fig. 73. — Differential locust: last stage of nympli with its cast skin on tip of com plant. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 105 the hind-wings are tinged with green; the hind-thighs are bright yellow, especially below, with four black marks; the hind-shanks are yellow with black spines and a ring of the same color near the base. The adults at once attack whatever crops are avail- able, often finishing the destruction of those injured by them as nymphs, but in a few days their appetites seem to become some- what appeased and they commence to mate and wander in search of suitable places for laying the eggs. Relatively few eggs are laid in cultivated ground, the favorite places being neglected fields grown up in grass and weeds, the edges of cultivated fields, private roadways, banks of ditches and small streams, and pasture lands. Alfalfa land is a favorite place for oviposition, and alfalfa is frequently seriously injured by this species. It is doubtless clue these egg-laying habits and the abundance of food on uncultivated land that this species always increases enormously on land which has been flooded and then lies idle for a }-ear or two. Most of the eggs are laid in August and early September. Each female deposits a single egg mass of about 100 eggs just beneath the surface of the soil. During this season the females may frequently be found with the abdomens thrust deep in the soil, as the process of egg-laying requires some time. The eggs are yellow and arranged irregularly in a mass which is coated with a gluey sul)stance to which the earth adheres, which protects them from variable conditions of moisture and tem- perature. Enemies. — As before mentioned, large numbers of the nymphs are destroyed before reaching maturity by their natural enemies. Among these a minute fungus undoubtedly kills many of those already somewhat exhausted, especially during damp weather. Almost all of our common birds, as well as many of the smaller mammals, are known to feed quite largely upon them. A small red mite (Ti-ombidium locustarum Rile}^, somewhat resembling the common red spider infesting greenhouses, is often of great value not only in killing the nymphs by great numbers of them sucking out the life-juices of the young hopper, but also in greedily feeding upon the eggs. 106 INSECT PESTS OF FARM, GARDEN AND ORCHARD The maggots of several species of Tachina-flies are of con- siderable value in parasitizing both nymphs and adult locusts. Their eggs are laid on the nock of a locust, and, upon hatching, ^ ^ c V - d Fig. 74. — A Locust-mite {Trombidium locustaruni): a, the larva as seen on locust's wing; c, male mite; d. female, the two latter appearing as when egg-destroyers — all greatly enlarged. (After Riley.) the maggots pierce the skin and live inside by absorbing its juices and tissues. When full grown the maggots leave the locust, descend into the earth, and there transform to pupae Fig. 75. — Anthomyia egg-parasite, a, fly; b, puparium; c, larva; d, head of larva. (After Riley.) inside of their cast skins, and from the pupae the adult flies emerge in due time. The maggots of one of the Bee-flies (Systoechus oreas) feed upon grasshopper eggs, but their life history is not fully known. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 107 The coninion Flesh-fly (Sarcophaga carnaria Linn.), Fig. 77, is also very destructive, though hirgely a scavenger. Fig. 76. — Two tachina-flies. {Exoristn leiicnnioe Kirk, and E. flavicauda Riley). (After Riley.) But of all the insects attacking locusts, the l^hster-beetles, which, unfortunately, are often known to us as very injurious to various garden crops, are probably of the most value. The female beetle deposits from four to five hundred of her yellowish eggs in irregular masses in loose ground, and in about ten days there hatch from these eggs some '' very active, long - legged larvae, with huge heads and strong jaws, which run about everywhere seeking the eggs of locusts." Each of these larva? will consume one of the masses or about Fig. 77. — Common flesh-fly (Sarco- phaga carnaria lAnn.): a, larva; b, pupa; c, fly. Hair-lines show natural size. (After Riley.) (^^_tt^«. W^^ t^lj- ,iy^^ -.-^^ Fig. 78. — Various stages of a blister-beetle (Epicauta vittata). (After Riley.) thirty eggs. The subsequent life history of these insects is very complicated on account of their peculiar habits, but the various stages are shown in Fig. 78. 108 INSECT PESTS OF FARM, GARDEN AND ORCHARD Control. — As the eggs are usually laid in the ground in the fall, deep plowing in late fall or early spring effectually buries them too deep for the young nymphs to emerge. On alfalfa land thorough disking is often used for the same purpose. Thorough harrowing in the fall so as to pulverize the soil for the depth of an inch will break up many of the egg masses, though it is not as sure a control as plowing them under. When the young emerge, they may sometimes be destroyed by burning over stubble, grass and rubbish where it is present in sufficient quantites, or by augmenting it with straw, which may be done to advantage on cold days when the nymphs are congregated in such shelter. If the surface of the ground is smooth and hard many may be killed by the use of a heavy roller, jDarticularly in the morning and evening, when they are sluggish in their movements. Plowing a badly infested field in a square, working toward the centre so as to drive the young nymphs inward, will result in l)urying many of them in the furrows, and the last may be burned or trapped in holes as described below. Simple ditches 2 feet wide and 2 feet deep form effectual barriers for the young hoppers. The sides next to the crop to be protected should be kept finely pulverized by hauling a log or a brush of dead branches through the ditch. The ditch may be made as described for chinch-bugs and is handled in the same manner, the little hoppers drifting to the bottom of the ditch, where they are killed by the heat on a hot day or where they are caught in post-holes sunk every few feet in the bottom of the ditch. This method may be used to advantage in plots of corn, cotton, or garden truck which has already become infested, by running furrows around the field and occa- sionally through it, and then driving the young hoppers toward them, which may be readily done by a number of children armed with branches. Where ditches containing water are available the young hoppers may be very effectively destroyed by oiling the surface of the water with kerosene emulsion (p. 48) and then driving them into the ditches, for even if they succeed in crawling out they will succumb to the oil. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 109 Where the young hoppers have congregated in large numbers on the edge of fields, in patches of weeds, etc., they ma}' be destroyed by spraying them with kerosene or crude petroleum either pure or, preferably, in an cnuUsion, and the weeds and Fig. 79. — Simple coal-oil pan or hopperdozer. (After Riley.) Fig. so. — The Price oil-pan or hopperdozer, with partitions to prevent slopping. (After Riley.) grass along fences and in neglected fields should be thoroughly treated with a strong arsenical spray or dust. In pastures, small grains or any crops permitting their use, immense numbers of the nymphs may be caught by the use no INSECT PESTS OF FARM, GARDEN AND ORCHARD INSECTS AFFECTING GRAINS, GRASSES, FORAGE 111 of hopperdozers, which may be utilized where the use of poisoned bran would not be possible. The hoppcrdozer consists of a shallow pan containing water with a surface of kerosene, crude petroleum, or coal tar, which is sometimes used without water. The pan is mounted on runners or wheels and if larger than about 3 feet square is usually provided with partitions to prevent slopping. The back and sides are high and sometimes are made of canvas. " A good cheap pan is made of ordinary sheet iron, 8 feet long, 11 inches wide at the bottom, and turned Fig. 82. — Carolina locust killed by fimgous disease. (Photo by Weed.) up a foot high at the back and an inch high in front. A runner at each end, extending some distance behind, and a cord attached to each front corner, complete the pan at a cost of about $1.50 (Fig. 80). We have known of from seven to ten bushels of young locusts caught with one such pan in an afternoon. It is easily pidled by two- boys, and by running several together in a row, one l^oy to each rope, and one to each contiguous pair, the best work is performed with the 112 INSECT PESTS OF FARM, GARDEN AND ORCHARD least labor." Larger pans are drawn or pushed by horses. The oil is best used on the surface of water, from which the insects are removed with a strainer, and any which hop out will die after having come in contact with the oil. Destroying the Adults. — The destruction of the winged insects is an entirely hopeless task, for, though even large numbers are caught, so many will remain that the damage done the crops would be but very slightly diminished. One of the most promising means for averting the swarms of winged migratory locusts from alighting in the fields is by a dense smudge, in which some foul-smelling substances are placed. Where strictly attended, and with favorable winds, this has often proved highly successful. To accomplish the best results farmers over an extensive area should combine in its use. The South African Fungus. — In 1900 Professor Morgan made a test of a fungous disease which had been found to destroy large numbers of grasshoppers in South Africa, to determine whether, after starting it ])y artificial propagation, it would spread suffi- ciently to destroy any considerable number of locusts. The weather was favorable, rains being frequent. Early in August it was found that " over the areas where the liquid infection was spread diseased hoppers were abundant." " As many as a dozen dead grasshoppers could be found upon a single plant, and some upon nearly every weed on ditch-banks where grass- hoppers were numerous. From the centres of infection great areas had become inoculated, spreading even beyond the planta- tions first infected." The property upon which it was placed became thoroughly infected with the fungus. Strangely, though many other species of grasshoppers were abundant, only the differential locust was killed by it. Dr. Howard states that this disease has also spread and done effective work in Colorado. However, more recent experiments made by the writer in Texas gave only negative results, and it is doubtful if any reliance can be placed upon the artificial use of such fungous diseases for locust control. Poisoning. — A mash composed of bran, molasses, water, and INSECTS AFFECTING GRAINS, GRASSES, FORAGE 113 arsenic or Paris green^ which has been extensively used for cut- worms, was found to be quite successful in the experiments of Mr. D. W. Coquillct in the San Joaquin Valley, California, during 1885, for protecting orchards, vineyards, gardens, etc., and might even be of some value for grain crops. Two pounds of Paris green, 25 pounds of bran, Imrely moistened with water and cheap molasses, will be aljout the correct propor- tion. It should be placed in the fields, a tablespoonful to each plant or vine. At this rate the cost per acre of vineyard, including labor, will not exceed fifty cents. The poison acts slowly, but if judiciously used will l^e found very effective, especially for the non-migratory forms. In Texas the mash has been found satisfactory in destroying the grasshoppers attacking cotton. One planter writes: '' We are successfully using arsenic (for grasshoppers) at the following rates : 10 pounds of wheat hran, H gallons sorghum molasses, 1 pound arsenic. Make a thick mash, sow broadcast on infected ground, and it will surely kill them. I used 40 pounds last year and made 49 bales of cotton. My neighbors did not do anything and entirely lost their crop." The writer has also seen excellent results from the use of the mash in Texas with only one pound of poison to 25 pounds of bran. However, Professor Morgan con- cluded that " the mash cannot be relied upon in severe outbreaks, such as occurred in the delta, but may be used in limited attacks where the area affected would not warrant the more aggressive methods." " When grasshoppers are young or half-grown, a poisonous bait, known as the C riddle Mixture, has proved effective in many parts of the countr}' (particularly for the Rocky Mountain locust). This consists of one part of Paris green and about one hundred parts of fresh horse manure, by measure. Enough water is added to make the mass soft without being sloppy. It can be taken to the field b}' a wagon or stone boat and scattered about by means of a paddle." — Washburn. 114 INSECT PESTS OF FARM, GARDEN AND ORCHARD The Army Worm* Almost every year some locality repoi'ts serious injury to crops by armies of caterpillars, which have not been previously known for many j-ears. This being the case the farmers are at a loss to combat them, and by the time information has been secured the pests have completed the damage. The Army Worm occurs throughout the United States east of the Rocky Mountains and lives in low, rank growths of grass, which form the normal breeding-grounds. When from an abundance of such food, or through failure of the parasites to prevent their increase, the caterpillars be- come overabundant, they as- sume the army habit and march en masse, consuming all in their path. The next 3'ear their natural enemies will usually have them under control again and there will be but little damage, and then they will not be observed as injurious for a series of years, though the moths are always fairly common. Life Historij. — In the North the moths appear early in June and the females lay the small yellowish eggs in rows of from ten to fifty in the unfolded bases of the grass leaves, covering them with a thin layer of glue. Over seven hundred may be deposited by one female, so that when the young caterpillars hatch in about ten days, the progeny of a few moths might form a quite destructive army. The worms usually feed entirely at night, and thus whole fields will sometimes be ruined before they are discovered, though a few generally feed by day, as they all do in cloudy weather. The leaves and stalks of grains * Lcucania uiiipuncta Haworth. Family Nocluida:, Fig. 83. — Army-worm moth {Leucania unipuncta), pupa, and eggs in natural position in a grass-leaf. Natural size. (After Comstock.) INSECTS AFFECTING GRAINS, GRASSES, FORAGE 115 Fig. 84. — Army worms at work on corn-plant. (After Slingerland.) IIG INSECT PESTS OF FARM, GARDEN AND ORCHARD and grasses form their favorite food, the heads usually being cut off, but various garden crops are often seriously injured if they happen in their path. Though usually untouched, even clover is not exempt. In from three to four weeks the worms have become full grown and are then about 1^ to 2 inches long, of a dark gray or dingy black color, with three narrow, 3'ellowish stripes above, and a slightly broader and darker one on each side, quite resembling cutworms, to which they are nearly related. They now enter the earth and transform to pupa?, from which the adult moths emerge in about two weeks. These lay eggs for another brood of worms which appear in September, but are very rarely injuri- ous. The moths which de- velop from this last brood either hibernate overwinter, or deposit eggs, the larvae from which become partially grown before cold weather and then hibernate. In either case the young larvse feed in the spring, not usu- ally doing much damage, pupate in May, and the moths of the first genera- tion appear in June as Thus in the North there are three broods a year, the young larvse usually hibernating, while in the. South there may be as many as six generations, and the moths usually hibernate over winter and lay their eggs in the spring. The moths very often fly into lights and are among the com- monest of our pla'n " millers." The front wings are a clay or fawn color, specked with black scales, marked with a darker shade or stripe at the tips, and with a distinct spot at the centre, Fig. 85. — An army w o r m — a bout one -third en- larged. (After Chittenden, U. S. Dept. Agr.) already described Fig. 86. — a, head of fall army worm; b, head of army worm — enlarged. (After Chittenden, U. S. Dept. Agr.) INSECTS AFFECTING GRAINS, GRASSES, FORAGE 117 which gives the specific name wiipuncta. The hind-wings are somewhat Hghter with blackish veins and darker margins. Enemies. — Were it not for other insects which pre}' upon the army worm, the army hal^it woiikl doubtless be more often assumed and we should have to deal with them more frequently. Ordinarily, however, the parasitic and predaceous insects hold them in check very efficiently and when an outbreak does occur, the later broods of the same season are often entirely destroj'cd by their insect enemies. Large numbers are always destroyed by the Fig. 87. — ^The farmer's friend, the red-tailed tachina-fly (Winthernia i-pustv^ lata): a, natural size; b, much enlarged; c, army worm on which fly has laid eggs, natural size; d, same, much enlarged, (.\fter Slingerland.) predaceous ground-beetles and their larva3 (p. 14), but their most deadly enemies are the tachina-flies (p, 106). These lay from a dozen to fifty eggs on a caterpillar, and the maggots from them enter the body and absorb the juices and tissues of the host, thus soon killing it. When feeding at night the worms are ordinarih" free from these parasites, but when the marching habit is assumed the flies swarm around them on cloudy days and before the next year they again have the remnants of the voracious army under subjection. Therefore, worms with the 118 INSECT PESTS OF FARM, GARDEN AND ORCHARD tachina-fly eggs on tliera (Fig. 87) should never be destroyed where avoidable. Control. — When detected, all efforts should be centred on keeping the worms out of crops not yet attacked and confining their injury to as small an area as possible. As a barrier to their progress, there is nothing better than a dust furrow made as already described for chinch-bugs (p. 91), two or three of which may be found necessary in cool weather or where a fine dust cannot be maintained. Deep fall plowing and thorough harrowing will be effective against the hibernating larva?, as will the burning of all grass along ditches, fences, and spots where the larvae normally live. By thorough spraying, or perhaps better by dusting, a strip of the crop with Paris green or some arsenical, and liberally distributing poisoned bran mash (see p. 47), large numbers may be destroyed. Where they are massed in furrows they may be destroyed by spraying them with pure kerosene or crude petroleum. As in fighting chinch-bugs the army worm must be given immediate and conclusive combat if the loss of crops is to be prevented, for they move rapidly and destroy all in their path. The Fall Army Worm * Though somewhat the same in its habits as the true army worm, the Fall Army Worm is so called because it appears later in the season, the former species being rarely injurious after August 1st. It is also more omnivorous, for while the army worm prefers .grasses, and grains, the fall army worm feeds upon a large variety of crops, including sugar-beets, cow-peas, millet, sweet potatoes, and many other forage and truck crops. In Nebraska and the Central West it is a serious pest of alfalfa and is called the Alfalfa Worm. It is also sometimes very de- structive to lawns, as was the case in Chicago in 1S99. The fall army Avorm is more of a native of the Southern States, but occurs from Canada to the Gulf and west to the Rockies. * Laph]jgma Jnujipcrda S. and A. Family Noctuidoc. INSECTS AFFECTING GRAINS, GRASSES, FORAGE 119 At first glance the catcrpilhirs have niucli tlie same general appearance as the army worm, but closer examination reveals marked differences. Along each side of the body is a longitudinal pitch-colored stripe, and along the middle is a yellowish-gray stripe about twice as wide, which includes four black dots on each segment. The caterpillars assume the habit of working in armies, but usually do not feed in such large numbers as the tme army worms and thus are more difficult to combat. Life History. — The winter is passed in the pupal state, the pupffi being about one-half inch long and being found in cells one-quarter to one- half an inch below the sur- face. The moths emerge in the spring and the females lay their eggs on grass in clusters of fifty or more, each mass being covered with the mouse- colored hairs from the body of the female. The eggs hatch in about ten days and the caterpillars are found during May and June. The complete life history of the insect has not been carefully followed, but it seems probable that there are but two complete generations in the North, three gen- erations in the latitude of central and southern Illinois and the District of Columbia, and four in the extreme South. In any event, the destructive brood of caterpillars appears in xVugust and early September. The parent moth is of a " general yellowish, ash-gray color, with the second pair of wings almost transparent, but with a purplish reflection. In extent of wings it measures about l\ Fig. 88. — The fall army-worm: a, moth, plain gray form; h, fore wing of Pro- denia-like form; c, larva extended; d, abdominal segment of larva, side view; e, pupa; d, twice natural size, others enlarged one-fourth. (After Chittenden, U. S. Dept. Agr.) 120 INSECT PESTS OF FARM, GARDEN AND ORCHARD inches, and when closed the length of the insect is about three- quarters of an inch. The front wings are mottled or marbled, especially near the central area, and usually there is visible a fine white line a short distance from the edge and parallel to it. The hind-wings have a fringe of darker hair as well as veins that contrast somewhat with the lighter portion " (Fig. 88). Control. — Deep fall plowing and thorough harrowung will break up the pupal cells and thus largely prevent the develop- ment of the spring brood of moths. In perennial crops like alfalfa thorough disking may be used and on lawns deep raking with a long-toothed steel rake will kill many of the pupa?. In fields of young grain and on lawns many of the caterpillars may be killed by a heavy roller. When not present in too large numbers, the worms may be destroyed by spraying the food plants with Paris green, arsenate of lead or other arsenicals, or by the use of poisoned bran mash. When present in large numbers and the army hal^it is assumed they should be cofh- bated the same as the army worm. CHAPTER VIII INSECTS INJURIOUS TO SMALL GRAINS * Meadow-maggots or Leather- jackets f Several instances have been recorded in which serious injury has been done to wheat, clover, timothy, and blue grass by the larvffi of Crane-flies. These insects are never so injurious in this country as in Europe, where they are known as " daddy- long-legs," the common name of our harvest-spiders, though doubtless injury done by them is often attributed to other insects. The farmer usually declares the work to be that of wireworms or cutworms, the adults often being known as " cutworm-flies," unless the maggots are so abundant as to attract his attention. When the maggots are abundant enough to do much injury, they usually occur in very large numbers, but ordinarily, though common everywhere, they are not numerous enough to attract attention. Several species (Tipula bicornis Loew, T. costalis Say, and Pachyrrhinis sp.?) have at various times done considerable damage in localities in Ohio, Indiana, Illinois, and elsewhere. Life History — So far as studied, the life histories of these species seem to be much the same. The larvse remain dormant over winter, but evidently commence feeding again very early in the spring, a wheat-field having shown the effects of their injuries from February 1st to April Lst. The larvse become full grown from the latter part of April until the middle of May, depending upon the species and season. The full-grown maggots are about an inch long, of a dirty-grayish color, and of a tough, * See " The Principal Insect Enemies of Growing Wheat," C. L. Marlatt, Farmers' Bulletin No. 132, U. S. Department of Agriculture. t Family Tipulidce. 121 122 INSECT PESTS OF FARM, GARDEN AND ORCHARD leathery texture. They are nearly cylindrical, somewhat taper- ing in front and terminating bluntly behind. Legs are entircl}^ wanting, but at the blunt end are a few fleshy processes and a pair of small, horny hooks. The larva seem to prefer low, moist ground, and will live for some time on land entirely flooded or in a ditch. They feed very largely on dead vegetable matter, but when exces- sively abundant they attack the roots of wheat, grass, and clover, so weaken- ing them near the surface that the plants, deprived of p rope r nourish- ment, are killed and loosened from the ground. Pupse may be found during the 4atter part of May, occupying small cells in a vertical position near the surface of the soil. Prior to emerging the adult pushes from one-half to two-thirds of the Ijody above the sur- face and reniains in this pose for several hours. The males usually emerge first, as their assistance is required by the females, which are loaded down with eggs, to extricate them- selves from the pupal skins. The sexes pair immediately, there being many more males than females — one observer states one hundred to one — and the females deposit their eggs upon grass Fig. 89. \ Crane-fly (Tipula hebes Loew): male adult. (After Weed.) INSECTS INJURIOUS TO SMALL GRAINS 123 and clover lands, to the number of three hundied each. Eggs are laid for another l)rood in September, the maggots from which live over winter. Remedies. — Injury to wheat-land may be large!}- prevented by plowing earh" in September. No satisfactory remedy for the maggots is known when injuring clover, timothy, or grass, although large numbers have been destroyed b}- driving a flock of sheep over infested land. Dr. S. A. Forbes states that " close trampling of the earth b}' the slow passage of a drove of pigs would doubtless answer the -same purpose, which is that of destroying the larva? lying free upon the surface or barely embetlded among the roots of the grass." Several of our common birds as well as a number of ground- beetles feed upon the maggots and flies. The maggots are also sometimes attacked by a fungous disease which in the damp soil in which they live doul)tless grows and spreads rapidly. Altogether these different enemies keep them so well in check that they rarely become of importance. The Hessian Fly * The Hessian fl}' is much the most destructive of any of the insects attacking wheat, to which its injury is practically con- fined; for though it occasionalh' injures barley and rye, it has never been reared on other grains or grasses. Its name was re- ceived from the fact that it was first noticed on Long Island in 1779, near where the Hessian troops had landed three years before. It now occurs over the main wheat-growing area of the eastern United States between parallels 35° and 45° westward to the 100th meridian, on the Pacific coast, in Canada, and in many other parts of the world where wheat is grown. Xot infrequently it destroys 25 to 50 per cent of the whole crop in some localities, and it has been estimated that 10 per cent of the crop of the whole couiitry is lost from its ravages. Life History. — The adult flies are little dark-colored gnats about * Mayetiola destructor Say. Family Cecidomyidoe. 124 INSECT PESTS OF FARM, GARDEN AND ORCHARD one-tenth inch long, so small as to commonly escape observation. Each female lays 100 to 150 minute reddish eggs, one-fifteenth inch long, placing them in irregular rows of from three to five or more, usually upon the upper surface of the leaves. In a few days these hatch into small, ^-eddish maggots, which soon turn white, are cylindrical, about twice as long as broad and have no true head or legs. The fall brood of maggots burrow beneath the sheaf of the leaf and its base, causing a slight enlargment at the point of Fig. 90. — ^The Hessian fly {Mayetiola destructor): a. female fly; b, flaxseed stage or pupa; c, larva; d, head and breast-bone of same; e, pupa; /, puparium; g-, infested wheat-stem showing emergence of pupce and adults. (After Marlatt,, U. S. Dept. Agr.) attack; but in the spring they usually stop at one of the lower joints, in both instances becoming fixed in the plant, absorbing its sap and destroying the tissues. The first indications of the work of the maggots on winter wheat in the fall are the tendency of the plants to stool out, the dark color of the leaves, and the absence of the central stems. Later many of the plants yellow and die. The spring maggots attack the laterals, or tillers, which have escaped the previous brood, so weakening them that the INSECTS INJURIOUS TO SMALL GRAINS 125 stems break and fall before ripening anil cannot l)e readily hai'- vested. Al)out four weeks after hatching the maggots are full grown, and arc greenish-white and aliout three-sixteenths inch long. The skin then turns brown, shrivels slighth', and inside it is formed the pupa. This outside case, composed of the cast larval skin, is known as the " puparium," and this stage is commonl}^ called the "flax- seed " from the resemblance to that seed. In this stage most of the fall brood passes the winter, the fli<'s emerging in A\)Yi\ or May, while the summer brood remains in the "flaxseed" stage in the stubble dur- ing the late sum- mer and emerges when the first wheat is planted in the fall, emerging later further south. Several species of small chalcis flies (page 19) parasitize thelarvieand pupae, and were it not for their assistance it would doubtless be difficult to raise wheat. As yet no practical method of increasing their al^undance has been devised, though colonies have been carried to regions where they were scarce. Control. — The principal means of avoiding injury by the Hes- sian fly in the winter wheat regions is late planting in the fall. Inasmuch as the flies appear within aljout a week and then dis- appear, if planting be delayed until after that time, but little of the wheat will be injured. Dry weather in late summer and early Fig. 9L — The Hessian fly, adult male — greatly enlarged-. (After Marlatt, U. S. D. Agr.) 126 INSECT PESTS OF FARM, GARDEN AND ORCHARD fall will delay the appoarance of the flies, even with normal tem- perature conditions, and the further south, the later they appear. From experiments being conducted by the U. S. Bureau of Ento- mology, Professor F. M.Webster states that the following dates will probably be found safe for sowing wheat in average seasons: in Fig. 92. — "Flax-seeds" or puparia of the Hessian fly on young wheat — enlarged. (After Pettit.) northern Michigan soon after the 1st of September; in southern Michigan and northern Ohio, about September 20th; in southern Ohio after the first week in October; in Kentucky and Tennessee, October 10th to 20th; in Georgia and South Carolina, October INSECTS INJURIOUS TO SMALL GRAINS 127 25th to November 15th. The exact time will also depend upon altitude as well as latitude. A rotation of the wheat crop compels the flies when they emerge from the stubble to travel in search of the young wheat plants. Should storms or heavy winds occur, the frail little flies will be de- stroyed in large numbers, whereas if they found wheat immedi- ately available the mortality would be small. Inasmuch as most of the spring Ijrood remain in the stubble in the flaxseed, stage after harvest, if the fields be then burned over, large numbers will be destroj'ed. This may be done by cut- A A P'iG. 93. — Hessian fly: o, egg, greatly enlarged; 6, section of wheat-leaf showing eggs as usually deposited — less enlarged; c, larva; d, pupa taken from puparium or "flaxseed" — e; c, d, e, much enlarged. (After Webster and Marlatt, U. S. Dept. Agr.) ting the grain rather high at harvest, and then mowing the weeds and grass and allowing them to dry a few days Ijefore burning. Unfortunately this practice is often impossible, owing to the prac- tice of seeding wheat land to grass and clover. As early volunteer plants always become badly infested and the pupae wintering on them give rise to a spring brood which attacks the main crop, all volunteer plants should l)e destroyed by plowing or disking before the larva have matured. This principle has some- times been utilized in the form of a trap crop, strips of wheat being sown early so as to attract the flies and then being plowed under 128 INSECT PESTS OF FARM, GARDEN AND ORCHARD after the bulk of the eggs had been laid upon them, thus protecting the main crop, planted later. The enrichment of the soil, the' preparation of a good seed bed, and the use of good seed, so as to secure a vigorous growing crop, are all of the greatest importance in overcoming injury by the Hessian fly. After the crop is once attacked, no truly remedial measures arc known except to appl}' liberally some quick-acting fertilizer which will cause the plants to tiller freely and give them sufficient vigor to withstand the winter and thus increase the healthy stems the next spring. Though none are exempt from attack, those varieties of wheat " with large, coarse, strong straw are less liable to injury than weak-strawed and slow-growing varieties." * In New York in man}' localities in 1901 a wheat called Dawson's Golden Chaff was found to be but little injured, where others were nearly destroyed. However, in Canada, where this variety originated, it is as seriously injured as other kinds, and may become so in New York. Bearded Red Wheat No. S was also found to be a very resistant variety, as were Prosperity, Democrat, Red Russian, and White Chaff Medi- terranean. It should be remembered, however, that none of these are invariably " fly-proof," and that though under certain conditions they may be but little injured, in other localities and under less favorable circumstances the}^ may be injured as much as any other sorts. Among other conclusions Professor Roberts* and his colleagues state that the fly " injures wheat more on dryish and poor land than on moist but well-drained, rich soils." Also, " that the soil must be so well fitted and so fertile that a strong, healthy growth will be secured in the fall, though the sowing of the seed be delayed ten to fifteen days beyond the usual time. Such preparation of the soil will also help the wheat to recover from any winter injury. Thick seeding and vigorous growth also tend to ward off the fly." " Much stress should be laid on the proper fitting of the land for wheat. Plowing should he done early — at least six weeks before * Cornell University Agr. Exp. Sta., Bulletin 194: The Hessian Fly, I. P. Roberts, M. V. Slingcrland, and J. L. Stone. INSECTS INJURIOUS TO SMALL GRAINS 129 sowing — to give abuiicUmt time for the repeated working of tlic soil in order to recompact the subsurface soil and secure a fine but shallow seed-bed in which there has been developed, by tillage and the action of the atmosphere, an abundance of readily available plant food. Manures and fertilizers should be kept near the sur- face and the young roots encouraged to spread out on the surface soil, thus avoiding much of the damage by heaving in winter and leaving the deeper soil for fresh pasturage for the plants during the following spring and summer." In summarizing his knowledge of means of controlling this pest, Professor F. M. Webster, who is probably our best authority upon it ,says: " After thirteen years of study of the Hessian fly, I am satisfied that four-fifths of its injuries may he prevented by a better system of agriculture. For years I have seen wheat grown on one side of a division-fence without the loss of a bushel by attack of this pest, while on the other side the crop was invariably always more or less injured. No effect of climate, meteorological conditions, or natural enemies could have brought about such a contrast of results. The whole secret was in the management of the soil and the seeding." The Wheat Saw-fly Borer * The "Corn Saw-fly" has for many years been a well-known wheat pest throughout England, France, and the Continent, but was not noted as injurious in this country till 1889, w^hen Professor J. H. Comstock published a very complete account of its injuries upon the University Farm at Ithaca, N. Y., where it had done more or less damage for two 3'ears, though Mr. F. H. Chittenden states that he collected a single adult at Ithaca in the early '80's. Specimens were also collected at Ottawa, Canada, and Buffalo, N. Y., in 1887 and 1888, and injury has been reported by Dr. James Fletcher from Manitoba and the Northwest Territories. The injury under Dr. Fletcher's observation, how- ever, was probabl}^ due to a nearly related species, the Western * Cephus pygmceiis Linn. Family Cephidce. Bulletin 11, Cornell Univ Agr. Exp. Station. 130 INSECT PESTS OF FARM, GARDEN AND ORCHARD Injury. Grass-stem Saw-fly (Cephas occidenlalis lliley and Marlatt). This is a native species which normally lives in wild grasses and which has been quite injurious in certain sections of the North- west during recent years. It hal)its and the means of control are practically identical with the species here discussed.! The following is gleaned from Professor Comstock's interesting account. No external indications of injury to the plant can be seen until the larva within has almost completely tunneled the stalk, at which time there is a discoloration just below the injured joints. Thus damage by this insect is not readily noticed, it merely dwarfing and stunting the growth of the plant by bor- ing in the stem. " If infested straws be ex- amined a week or ten days before the ripening of the wheat, the cause of this injury can be found at work within them. It is at that time a yellowish, milky- white worm, varying in size from one-fifth to one-half an inch in length. The smaller ones may not have bored through a single joint; while the larger ones will have tunneled all of them, except, perhaps, the one next to the ground. Life History. — " As the grain becomes ripe the larva works its way toward the ground ; and at the time of harvest the greater number of them have penetrated the root. Here, in the lowest part of the cavity of the straw, they make preparations for pass- ing the winter, and even for their escape from the straw the t See F. M. Webster, Circular 117, Bureau of Entomology, U. S. Dept. Agr. Fig. 94. — The wheat saw-fly liorer (Cephus pygmceus Linn.): a, ou'- hne of larva, natural size; b, larva, enlarged ; c, larva in wheat-stalky natural size; d, frass; e, adult female;/, Pachyonerus calcitrator , female, a parasite — enlarged. (After Curtis, from "Insect Life.") INSECTS INJURIOUS TO SMALL GRAINS 131 following year. Tliis is done by cutting the straw circularly on the inside, nearl}- severing it a short distance, varying from one-half to one-inch, from the ground. If the wheat Were grow- ing wild, the wint(n- winds would cause the stalk to l)reak at this point; and thus the insect after it had reached the adult state couhl easily escape; while but for this cut it would be very, liable to be imprisoned in the straw." OrcUnarily, the straw is cut by the reaper before it becomes broken; but a strong wind Fig. 95. — The western grass-stem saw-flj^ (Ccphun occidental i s) : a, larva; b, female saw-fly; c, grass-stem showing work, c, enlarged, a, b, more enlarged. (After Marlatt, U. S. Dept. Agr.) just before harvest Avill cause a large number of stalks to become broken, much as if affected by the Hessian fly. " After the circidar cut has been made, the larva fills the cavity of the straw just below it for a short distance with a plug of borings. Between this plug and the lower end of the cavity of the straw there is a place about one-half an inch in length. It is here that the insect passes the winter." This cell is lined with silk so as to form a warm cocoon. Here the larva passes the winter and changes to a pupa in March or April. The adult insect emerges early in May. The adults are four-winged insects, 132 INSECT PESTS OF FARM, GARDEN AND ORCHARD and are popularly known as saw-flies on account of the saw-like ovipositor of the female, by means of which she inserts her eggs in the tissue of the plant. This species is quite different in some respects from the saw-flies feeding upon the leaves of wheat, and belongs to the family Cephidce. The female commences to lay eggs by the middle of May. By means of her sharp ovipositor she makes a very small slit any place in the stalk of the plant and in this thrusts a small white egg — about Vioo of an inch long — which is pushed clear through the walls of the straw and left adhering to the inside. Though several eggs are deposited in a straw, but one larva usually develops. " The eggs hatch soon after they are laid, and the larvae may develop quite rapidly. A larva which hatched from an egg laid May 13th was found t-o have tunneled the entire length of the stalk in v/hich it was " on May 28th. Remedies.—" The most obvious method of combating the insect is to attack it while it is in the stubble; that is, sometime between harvest and the following May. If the stubble can be burned in the autumn, the larva3 in it can be destroyed. The same thing could be accomplished by plowing the stubble under, which would prevent the escape of the adult flies. But as it is (often) customary ... to sow grass-seed with wheat, it is feared that the plowing under of infested stubble would rarely be prac- ticable; and it is also questionable if the burning of the stubble could be thoroughly done without destroying the young grass. It would seem probable, therefore, that if this insect becomes a very serious pest, it will be necessary. . . either to sow grass- seed with oats and burn or plow under all the wheat stubble, or to suspend growing wheat for one year, in order to destroy the insects by starvation." Some Wheat-maggots Very similar to the Hessian fly in its mode of injuring the wheat-stalk is the Wheat-stem Maggot {Meromyza americana Fitch). The adult flies were first described by Dr. Fitch in 1858, INSECTS INJURIOUS TO SMALL GRAINS 133 though the work of the maggots had probably been noticed as early as 1821 by James Worth of Bucks County, Pa., and by the Michigan Farmer in Michigan about 1845. Extending from Dakota and Manitol)a to Texas, the range of this insect practically covers all the eastern United States and southern Canada. Unlike the Hessian fly it feeds and brectls upon wild grasses and is thus much more difficult to control. Prof. A. J. Cook found the larvffi in both barley and oats in Michigan, Prof. F. M. Webster reared an adult from blue grass {Poa praten- sis), and Dr. Jas. Fletcher records it as breeding in Agropi/noii, Des- champsis, Ehjmus, Poa, and Setaria viridis in Canada. Life Histori/. — Like the Hessian fly the adult flies lay their eggs on fall wheat in Sep- tember and Octo- ber, and the young maggots when hatched work their way down into the stem, either cutting it off or causing it to discolor or die. The eggs are about one-fortieth of an inch long and of a glistening white color. The larvae are a light greenish color, about one-fourth of an inch long, tapering toward the terminal end while subcylindrical posteriorly, being quite elon- gate. The pupie are the same color as the larva?, but more rounded, being only one-sixth of an inch long, and reveal the legs and wing-cases of the imago forming within them. The Fig. 96. — Wheat bulb-worm {Meromyza americana): a. mature fly; 6, larva; c, puparium; d, infested wheat-stem — all enlarged except d. (After Marlatt, U. S. Dept. Agr.) 134 INSECT PESTS OF FARM, GARDEN AND ORCHARD external case of the pupa, called the puparium, is merely the shrunken and hardened cast skin of the last larval stage, within which the insect transforms to the pupa. The fly is about one-fifth of an inch long. It is of a yellowish-white color with a black spot on the top of the head, three broad black stripes on the thorax, and three on the abdomen, which are often interrupted at the sutures, so that they form distinct spots. The eyes are a bright green. The winter is passed by the larvai in the young plants and in spring they transform to pupae and adult flies. These in turn deposit eggs in such a position that the mag- gots issuing from them may readily feed upon the succulent portions of the growing stalk. Numerous larvse thus sapping the life of the plant soon kill it out- right or cause the top and head to wither and die. The adults of this brood emerge in July and lay eggs on volunteer wheat and grasses, the maggots working in the same manner as in the fall and coming to maturity so that another brood of flies lays eggs for the fall brood on the newly planted wheat. Owing to the fact that this insect breeds also in grasses dur- ing late summer it is much more difficult to combat than were it confined to wheat as its food-plant, as is the Hessian fly. Remedies. — '' If the grain is stacked or threshed and the straw stacked or burned," says Professor Webster, " it is clear that Fig. 97. — The American frit-fly (Oscinin variabilis Loew): a, larva or maggot; b, puparium; c, adult fly. (After Garman.) INSECTS INJURIOUS TO SMALL GRAINS 135 the number escaping would be greatly reduced," for, as the adults emerge soon after harvest, they would escape to deposit their eggs were the straw left in the fields, but "it is not likely that those in the centre of the stacks would be able to make their wa}' out, and the threshing-machine would destroy many more. How much could be accomplished l)y late sowing of grain is uncertain, as the females are known to occur abundantly up to October. If plots of grain were sowed immediately after harvest in the vicinty of the stacks, many of the females could, no doubt, be induced to deposit their eggs therein, and these could be destroyed by plowing under." Burning of the stubljle will also aid in keeping this pest under control. There are several undetermined species of flies belonging to the genus Oscinis, which have practically the same life history as the wheat stem-maggot and injure the wheat in the same manner. They very closely resemble the common house-fly in miniature, being about one-fourth as large. They will not need consideration by the practical farmer other than in applying methods of control as already given. One species of this genus, determined by Professor H. Garman as Oscinis variabilis Loew and christened the American Frit-fly, has been found common in Kentucky antl Canada, but in the larval stage is so nearly identical in appearance and habit with the stem-maggot that it can with diTiculty be distinguished from it. That these pests do not do more injury is probably due, to a considerable extent, to the fact that large numbers of them are destro3'ed by a small hymenopterous parasite, known as Coelinus meromyza: Forbes, w^hich very commonly infests the larvae, and by other parasites and preclaceous insects. Rarely will these pests do serious damage, but very often it is sufficient to merit consideration, and only a knowledge of their life history can give a key to their successful control. 130 INSECT PESTS OF FARM, GARDEN AND ORCHARD The Wheat Joint-worm * For the last sixty years the joint-worm has been known as a serious pest of wheat throughout the wheat-growing region east of the Mississippi River, the damage varying from a slight injury which is hardly noticeable, and which may escape observation for several years, to an almost total destruction of the crop. The adults appear in April, May, or early June, according to the latitude, and are small black, four-winged flies about one-eighth inch long, with the joints of the legs and feet yellow. They look s o m e t h i n g like small, winged black ants (Fig. 99) and curiously enough belong to a family whose members are almost all parasitic on other insects, so that before they had been thoroughly studied they v/ere thought to be para- sites of the Hessian fly. The females lay their eggs in the stems, generally selecting the uppermost joints that have appeared at that time. " The young worms develop rapidly, each in a little cavity within the straw. Often knots, swellings, and twistings occur in the straw at the point of infestation; again there is little sign of the insect's presence except a slight discoloration or a little deviation of the fibres and grooves of the straw from their natural course. When the infested section is split with a knife it is found to be jjrittle and * Isosoma tritici Fitch. Family Chalcididce. See J. S. Houser, Bulletin 226, Ohio Agr. Exp. Sta.; and F. M. Webster, Circular 66, Bureau of Ento- mology, U. S. Dept. Agr. Fig. 98. — a, wheat-straw affected by joint-worm; b, adult as seen from above. (After Riley.) INSECTS INJURIOUS TO SMALL GRAINS 137 woody in character, and contains from 3 or 4 to 20 or more yel- lowish hirvie, aljout one-eighth inch long when full-grown. These larva; remain in the straw until the following spring, when they issue as adults and commence again the life cycle in the new crop. The damage is done by the worms cutting off the sap supply from the head, causing it to become shortened, containing comparatively few kernels, and such kernels as develop are apt to be small and shriveled from lack of nourishment. Also because of the brittleness of the straw high winds are apt to break much of it down." — Gossard. The presence of the pest is always indicated at threshing by Fig. 99. — Wheat straw-worm (Isosoma gj-andcJiiley): o, ventral view; 6, side view of larva; c, antenna?; d, mandible; e, anal segment, ventral view; /, adult female; g, fore-wing; h, hind-wing; i, aborted wing. (After Riley.) short, hard bits of straw, containing the larva?, which are carried out with the grain instead of going over in the straw. It has usually been considered necessary to separate and burn these, Init Professor F. M. Webster finds that the larvae in them are probably killed in threshing, as he has been unable to rear adults of cither the joint-worm or'its parasites from such bits of straw. Control. — A rotation of the wheat crop is of primary impor- tance in the control of this pest, and where wheat is not planted on the same land and is sown as far from that of the previous 138 INSECT PESTS OP^ FARM, GARDEN AND ORCHARD year as possible there will be but little damage. It is obvious that the stubble should be plowed under where possible, or burned during the late fall or winter. Cut infested grain as low as pos- sible so as to remove the larvaj in the straw. Where the stubble cannot be burned, break it down by harrowing in the spring and then collect with a hayrake and burn. Prepare the seed bed thoroughly and fertilize well, when injury is expected, so as to Fig. 100. — Swellings made by wheat joint-worms in straw — enlarged. (After Pettit.) ensure a strong growth and early ripening. Green manure containing infested straw should not be scattered on land to be used for wheat, and all infested straw which has not been used up by April should hv Ijurned. The Wheat Straw-worm * '' The Wheat Straw-worm," says Professor F. M.Webster,'' sus- tains the same relation to winter-wheat culture west of the Miss- issippi River that the joint-worm does to the cultivation of this cereal east of this river. Both, when excessively abundant, occasion losses from slight to total. A wheat stem attacked by the joint-worm may produce grain of a more or less inferior quality and less of it; but the spring attack of the wheat straw- * Isosoma grandc Riley. Family Clialcididw. INSECTS INJURIOUS TO SMALL GRAINS 139 worm is fatal to the plant affected, as no grain at all is produced, and while the second generation of the same has a less disastrous effect in the field, it nevertheless reduces the grade and weight of the grain." Though the straw-woi"m occurs over much of the same territory in the East as the joint- worm, it is rarely so injurious. Life History and Description.'^ " There are two generations of the insect annually, the adults of the first generation differing considerably in appearance from those of the second. To the farmer they will all look like minute or large, shining black ants, I'iG. lOL — Wheat straw-worm: adult of fall generation, much enlarged. (After Howard, U. S. Dept. Agr.) with or without wings, their legs more or less banded with yellow, and having red eyes. Individuals of the first generation emerge in April from the outstanding straws and stubble. They are very small, most of them are females, and many are wingless. The females deposit their eggs in the young wheat plants, the stems of which at this time extend but little above the sur- face of the ground. The egg is placed in or just below the embryonic wheat head and the larva or worm works within * From Circular 106, Bureau of Entomology, U. S. Dept. Agr., by F. M. Webster and Geo. I. Reeves. 140 INSECT PESTS OF FARM, GARDEN AND ORCHARD the stem, usually causing a slight enlargement. When the worm is full grown it will be found in the crown of the" plant, having eaten out and totally destroyed the embryonic head, its body occupying the cavity thus formed. "The females which deposit these eggs, being small and fre- quently wingless, are in no way fitted for traveling long dis- tances. The larva or worm is of a very light straw color, indeed almost whit(\, with Ijrown jaws. These worms develop very rapidly and; as they feed on the most nutritious part of the plant, they become robust and larger than those found in the mature straw in late summer. In May the larvae become full grown and pass at once through a short pupal stage. The pupae are at first the same color as the larvae, but later change to a shining jet black. In a few days the fully devel- oped insects gnaw circular holes through the walls of the stem and make their way out. These adults are much larger and more robust than the individuals of the first generation and are provided with fully developed, serviceable wings. That they make good use of their wings, and scatter themselves about over fields adjacent to their place of development, is shown by their occurrence in fields of grasses (in the stems of which they do not breed) situated considerable distances from wheat fields. In ovipositing, the females of this generation select the largest and most vigorous-growing stems in which to place their eggs. " The adults of the second generation deposit their eggs a Fig. 102. — The wheat straw-worm: method of oviposition of female of summer form: a, female inserting her eggs, h, section of wheat stem, showing egg; c, and ovipositor, d; c, egg, greatly magnified. (After Riley and Webster, U. S. Dept. Agr.) INSECTS INJURIOUS TO SMALL GRAINS 141 from early Ma}', in Texas, up to the mitldlc of June, in northern Indiana, or about the time the wheat is heading. Their aim at this time is to phice the eggs singly in the growing stem, just above the youngest and most succulent joints, which are not so covered by the enfolding leaf sheaths as to be inaccessi- ble to them. Thus it is that the stage of advance- ment in the growth of the wheat stem at the time of oviposit ion of the summer generation of females determines whether the larvie will be well upward in the straw, and there- fore removed after har- vest, or lower down and consequently left in the field in the stubble. " The methotl of ovi- position and the point where the egg is usually formed is shown in Fig. 103. The larva forms no gall, nor does it harden the stem witiiin which it develops. There is nor- mally but one larva in each joint; but if several eggs have been placed between joints and produce larvse there will be one in the centre of the stem just above the joint and others in the walls just under the internal wall-covering or inner epidermis. These larvse in the walls of the straws do not, as a rule, kill the stem, but their effect is to ciutail the yield by reducing the weight. The larva? develop rapidly and reach their full growth before the Fig. 103. — Wheat straw-worm, sho^ving point where female of the spring form deposits the egg in young wheat in early spring. Enlarged showing position of egg at right. (After Wester, U. S. Dept. Agr.) 142 INSECT PESTS OF FARM, GARDEN AND ORCHARD straw has hardened. By October^, in the Middle West, though earlier in the South, they pass into the pupal stage, in which, as a rule, they remain until early spring, whereupon they develop to adults and gnaw their way out." In the Northwest, w^here both winter and spring wheat are grown, the injury is particularly severe to spring wheat, as the adults of the second generation from winter wheat oviposit upon it while it is still young and ruin it in much the same way as the first generation does on the winter wheat in spring. Volunteer plants which carry the pest over winter have the same effect in increasing the injury to spring wheat. Control. — A rotation of crops which will eliminate the growing of wheat two years in succession on the same land is by all means the most successful and practicable means of control. The adults of the first generation are very small and largely wingless; they are unable to migrate far, so that rotation is exceedingly efficacious, though it should be planned so that wheat is not planted next to stubble land, for the edge will become infested by the first genera- tion, and the second generation will then become distributed throughout the field. The burning of stuljble and outstanding straw will be advantageous wherever practicable. Clean fallow- ing in early summer and the abandonment of spring-wheat culture will reduce injury in the Northwest. Wheat Saw-flies * Several species of saw-fly larvsc sometimes feed on the leaves and rarely on the heads of wheat, but seldom do serious injury. Dolerus arvensis Say and Dolerus coUaris Say have both been reared upon wheat from Ohio and New Jersey, though both species occur throughout the United States and southern Canada east of the Rockies. The adult flies " are comparatively large, robust in- sects, of a dull black or bluish color, varied with yellow or reddish." " The larvse are quite uniform in color and general characteristics. They have twenty-two legs, are cj'lindrical, and generally of a INSECTS INJURIOUS TO SMALL GRAINS 143 uniform grayish or slaty color, dorsally and laterally, but nearly white ventrally." * The adults deposit their eggs in the spring, and larvaj are to be found early in June. The only record found of the life history is that of D. collaris by Professor F. M. Webster, who found that a larva collected on June 15, 1897, entered the ground in about ten days, and the first adult emerged January- 11, 1S9S, though the adults usually appear later. The most common saw-fly feeding upon wheat foliage is Fig. 104. — .V wheat saw-fly (Dolerns arvensis Say) : female — much enlarged. (After Riley and Marlatt, U. S. Dept. Agr.) Pachynematus extensicornis Norton. " The adult insects appear during the latter part of April and first of May, the males antedat- ing the females several days. The eggs, when first laid, are of a light green color. They are inserted to the number of two to five, or more, together along the edges of the wheat-blades and just beneath the epidermis. Some fifteen or sixteen days elapse before hatching. The newly hatched larva is rather slender and elongate, tapering gradually from the head to the last segment; head yel- lowish, eyes black. Full growth is attained in about five weeks, ♦Family Tenthredinidoe. AVheat and Grass Saw-flies. C. V. Riley and C. L. Marlatt, " Insect Life," Vol. IV, p. 169. 144 INSECT PESTS OF FARM, GARDEN AND ORCHARD the mature larva having a length of about four-fifths of an inch. The head is of a pale clay-yellow color, the c}'es are black, and the color of the body is green or yellowish green. The larva is at once separated from the Dolerus larvse by the possession of but seven pairs of abdominal feet." (R. and M., I.e.) When full-grown the larvae enter the earth and construct silken cocoons, in which they Fig. 105. — The grass saw-fly {Pacliynematus extensicornin Norton) : a, a, eggs on wheat-blade; young larva"; c, full-grown larva; d, cocoon from which adult has emerged; e, /, adult insects — c, male; /, female, a and h, naturalsize; c-/, enlarged, (.\fter Riley and Marlatt, U. 8. D. Agr.) doubtless remain unchanged over winter, transforming to pupae shortly l^efore the adults emerge the next spring. The form of the adults is well shown in the illustration. '' The female is stout and in general light yellowish or ochi-aceous in color. The abdomen is for the most part daik bi'own oi' black, doi'sally, except the pos- terior lateral nuirgin and the extreme tip. The male is much more slender and elongate than the female, and is almost black in color, IXSECTS INJURIOUS TO SMALL GRAINS 145 the tip of the abdomen being reddish and part of the legs whitish." This species has been taken on wheat in Illinois, Nebraska, Dela- ,vare, Maryland, Ohio, Indiana, and Pennsylvania. During 1886 and 1SS7 it did considerable damage by cutting off the heads, — sometimes, as stated by a Maryland man, cutting fully one-half of them. No more recent damage has been recorded, and owing to the slight injury usually clone no remedies have received a prac- tical test. Deep fall plowing might be of advantage by burying the larva^ so deeply that the adults would be unable to escape. The Wheat-midge * Hisfonj. — While the Hessian fly attacks the stalk of the wheat-plant, another species of the same genus, known as the Wheat-midge, or " Red Weevil," often does very serious damage to the maturing head. It, too, is a foreigner, having first been noticed as injurious in Suffolk, England, in 1795, though probable references to its depredations date back as early as 1741. "In ' Ellis's Modern Husbandman ' for 1745 the attacks of the vast numbers of black flies (the ichneumon parasites) are noticed in the following quaint terms : ' After this we have a melancholy sight, foi', as soon as the wheat had done blooming, vast numbers of lilack flies attacked the wheat-ears and blowed a little yellow maggot which ate up some of the kernels in other parts of them, and which caused multitudes of ears to miss of their fulness, acting in some measure like a sort of locust, till rain fell and washed them off; and though this evil has happened in other summers to the wheat in some degree, yet if the good providence of God had not hindered it they might have ruined all the crops of wheat in the nation.' (Hind's 'Essay on Insects and Diseases Injurious to Wheat Crops,' page 76)". It seems probable that it was first introduced into America near Quebec, where it " appears to have occurred " iji 1819, and was first observed in the United States * Diplosis tritici. Family Cecidomyidie. See Bulletin No. 5, VoL I, 2d Sex., Oliio Ag. Exp. Sta., F. M. Webster. 146 INSECT PESTS OF FARM, GARDEN AND ORCHARD in northwestern Vermont in 1S20. It did not become very destructive, however, until 1828, from which time until 1835 is kept increasing in such numbers as to cause the abandonment of the wheat crops in some localities throughout northern New England. Serious damage was reported as due to this pest every few years until about 1860, being most severe in 1854, in which year Dr. Fitch estimated the loss in New York alone at $15,000,000, and in 1857, and 1858. Since then no widespread injury has occurred, though local outbreaks are frequent, and Fig. 106. — Wheat-midge {Diplosh tritici): a, female fly; fe, male fly; c, larva from below. (After Marlatt, U. S. Dept. Agr.) it has spread south to the Gulf States and westward to Iowa, Minnesota, and Arkansas. Life History. — The adult flies are small, two-winged insects, about an eighth of an inch long, of a yellow or orange color. They appear about the middle of June and lay the eggs " in a small cavity at the summit of, and formed by a groove in, the outmost chaff covering the incipient kernel." They hatch in about a week, according to Dr. Fitch, and the maggots burrow into the forming kernels. The maggots are of a reddish color, and when an ear is badly infested give it a reddish tinge, on account of which the insect is often called the " red weevil." INSECTS INJURIOUS TO SMALL GRAINS 147 When full grown the larvie enter the ground and usually form cocoons, in which they pass the winter in the pupal stage? though they often hibernate without such protection. Though doubtless there is usually but one brood in a season, observations b}' Professor F. M. Webster and others seem to point to the fact that there sometimes are two broods, as adults have been ol)servcd from August into November. Besides wheat, the wheat-midge also sometimes injures rye, barley, and oats. Remedies. — Plowing infested fields in the fall so deeply that the midges will be unable to reach the surface upon developing in the spring is by far the best means of controlling this pest, while Inirning the stubble previous to plowing, and a rotation of the crop, will also be of considerable aid. The English Grain-louse * The most common plant-louse affecting wheat and other small grains is a large green species which is always to be found on wheat plants, but which occasionally increases very rapidly, and clustering on the ripening heads sucks the juices so as to seriously injure the quality and weight of the wheat. In the North the first individuals are found on 3'oung wheat in April, though dui'ing open winters they may be found on the plants, and in the South they continue to reproduce' during most of the winter in open seasons. The aphides feed upon the leaves until the grain commences to head, when they assemble on the heads among the ripening kernels. The females give birth to live young, bearing from 40 to 50 each, which become full grown in ten days to two weeks, and then reproduce, as is the usual method of reproduction with plant-lice (see page 442), so that they * Macrosiphum granaria Buckton. Family Aphididte. A nearly related species, Macrosiphum cerealis Ksdtenhiich, has very similar habits, is commonly associated with the species, and has not been distinguished from it by most WTiters. It may be recognized by lackins; the blackish markings on the abdominal segments. See Pergande, Bulletin 44, Bureau of Entomology, U. S. Dept. Agr. 148 INSECT PESTS OF JFARM, GARDEN AND ORCHARD multiply with great rapidit}', and where so few were present as to be hardly noticeable, in a few weeks they will be swarming over the heads in myriads. As the small grains ripen they migrate to various grasses and are not much in evidence during midsummer, but later migrate to volunteer oats and wheat, upon which they subsist until fall wheat is available. Owing to the cool weather of fall and the fact that ]:)ut few individuals survive the attacks of their parasites during the summer, they rarely become aljundant enough to do any damage to grains in the fall. So far as known, they hibernate over winter among the leaves of the growing plants, enough surviving l)oth snow and cold to infest the crop the next spring. Whether true males and females produce eggs on the grain is unknown, for though they have been reared under artificial conditions, they have never l^een observed in the field. Professor F. L. Washburn observed at least fourteen generations up to November 8, 1907, in southern Minnesota. As with other aphides, both winged and wingless individuals occur throughout the season. The wingless individuals are about one-tenth inch long, with l)lack antennae as long or longer than the hody, are of a yellowish-green color, often slightly pruinose, and long black nectaries extend from either side of the abdomen. The winged individuals are about the same length, with a wing expanse of about three-eighths inch, with antenna? a third longer than the body, and are of the same general colora- tion except that lobes of the thorax are brown or l^lackish, and Fig. 107. — The German grain aphis {Macro- siphum cerealis Kah): a, winged migrant; b, nymph of same; c, wingless partheno- genetic female; d, same showing exit hole of parasite — enlarged, (.\fter Riley, U. S. Dept. Agr.) INSECTS INJURIOUS TO SMALL GRAINS 149 the abdomen is marked with four or five transverse blackish spots in front of the nectaries. Like the other apliides affecting small grains, this species is held in check by parasitic insects, aided by predaceous insects and fungous diseases. Injury by the aphides is usually due to the parasites having been killed off, thus giving the. aphides opportunity to multiply unchecked. Among the most abundant parasites are species of the genus Aphidius (family Braconidce), Fig. 108. — Grain aphides clustered on wheat head, greatly enlarged. (After Weed.) Fig. 109. — Wheat-louse parasite (Aphidius avenaphis Fitch), and parasitized louse from which it has issued. (Copied from J. B. Smith.) one of which is shown in Fig. 109, greatly enlarged. Cold, wet weather in spring greatly retards the development of these para- sites, so that the aphides are always more numerous in such seasons. It has also been ol^served that an outbreak is often preceded by several dry seasons, which may be due to the fact that such dry seasons check the development of fungous diseases which kill off large numbers of the aphides and which do not propagate in hot dry weather. Thus weather conditions are very intimately 150 INSECT PESTS OF FARM, GARDEN AND ORCHARD associated with the abundance of the pest. When the parasites become abundant they will often completely rid a field of the aphides within a few days. All of the common ladybird-beetles (Coccinellidce), Syrphus-fiy larvae, and lace- winged fly larvae (Chrysopidce) are commonly found f(H^ding upon the aphides. Control. — No practical remedy for this species is known nor are means of control easily suggested. The suppression of volunteer wheat and oats in early fall will prevent the multiplica- tion of the pest before fall-sown wheat is available, and the late sowing of wheat in the fall will reduce the numbers entering hibernation. A wise rotation and the thorough preparation of the seed-bed and liberal fertilization will be of value in avoid- ing injury in the same way as has been described for other pests of small grains. Fortunately this spscies rarely does very wide- spread injury and its parasites usually soon bring it under control. The Spring Grain-aphis or Green Bug * Though long known as a serious pest of small grains in Europe, this aphis has done widespread injury in this country only during the past ten years. Though it occurs throughout the territory north of latitude 41°, with the exception of the North Atlantic States, as far west as longitude 105°, the worst injury has been done in northern Texas, Oklahoma, and Kansas, though it has also been injurious in the Carolinas and Tennessee. The habits of the insect during the winter have not been suffi- ciently studied to speak authoritatively, but it seems probable that it normally passes the winter in the egg stage, the small shin- ing black eggs, one-fortieth inch long, being laid on the leaves in the late fall. In the South, however, it often continues " to reproduce throughout the winter, and with a mild winter the numbers so multiply that unless checked by parasites serious injury is done by late winter or early spring. Both wingless and winged forms occur throughout the year. The wingless female is from one-twenty-fifth to one-fourteenth inch long, yellowish- green, with a median line slightly darker, eyes and most of the * Toxoptcra graminum Rond. Family Aphididoe. INSECTS INJURIOUS TO SMALL GRAINS 151 antenriiP black, of the shape shown in Fig. 112. The winged female is slightly larger, with a wing expanse of about one- quarter inch, and of the same general coloration, except that the head is brownish-yellow and the lobes of the thorax are blackish. The aphides hatching from the eggs are all females, which give birth to live young, no male forms occurring during the summer. During her life of slightly over a month a female will give birth to 50 or 60 young, which commence to reproduce in the same manner Fig. 110. — The spring grain-aphi.s or "green bug" (Toxoptera gramimum) : a, winged migrant; b, antenna of same, a, much enlarged; b, highly magnified. (From Pergande, U. S. Dept. Agr.) when about seven days old, so the numbers of the pest obviovish' increase with enormous rapidity, and with thousands of tiny beaks pumping out the sap the young grain plants soon succuml). The rate of reproduction and growth is, of course, much slower in colder weather, the above being the average for the growing season. Thus in an open winter the aphides will continue to multiply, and by February, in northern Texas, small spots of wheat and oats will show the effect of their work, by March the injury may become widespread and serious, and by the middle of "April the crops may be ruined. As the aphides become excessively abundant and the 152 INSECT PESTS OF FARM, GARDEN AND ORCHARD food supply disappears, almost all develop wings, and immense clouds of the winged females are carried northward by the winds, so that an outbreak in early spring in the South leads to an infestation farther north, and excessive multiplication will again carry the pest still northward, progressing in that direction as it increases during the season, rather than being spread at one time. Thus in 1907 it became abundant in Oklahoma in April, in Kansas 1 *■■ (r *1 i 1 Fig. hi. — Green bugs on oat-scedling — enlarged. in May, and by July it was found in Minnesota, where it rarely occurs and does no damage. With the maturing of wheat and oats the aphides migrate to various grasses, being particularly fond of Kentucky blue-grass, and may subsist on corn, on which they may feed until oats and wheat are available in the fall. Oats are the favorite food, and outbreaks of the pest have always been worst where volunteer oats are generally grown, the aphides increasing on them in the early fall and winter and later spreading to wheat. By October 15th in Minnesota and by early November in Kansas the true winged males and wingless egg-laying females have been INSECTS INJURIOUS TO SMALL GRAINS 153 observed, but strangely enough they have only been secured in small numbers by being reared in the laboratory, and have not been observed in the field, so that although these females laid eggs freely on the leaves of grain, we do not know whether they are essential or not to the life history of the insect in the field, for while the eggs are being produced other females continue to give birth to live young until the cold of winter, and they have been Fig. 112. — Toxoptcra gramiaum: o, newly born, and b, adult wingless green bug, greatly enlarged. (After S. J. Hunter.) observed to reproduce with a daily mean temperature barely above freezing. Natural Control. — The natural control of this most destructive pest involves a most interesting relationship between temperature and the development of the parasites which check its development. " The ' green bug ' in normal years — that is, when its breeding begins in spring — is effectively held in check by its natural ene- mies, and notably by a minute, black wasp-like insect, Lysiphlebus testaceipes Cress. (Fig. 113), that deposits eggs singly in the 'green 154 INSECT PESTS OF FARM, GARDEN AND ORCHARD bugs,' the grubs hatching from the eggs feeding internally on the bug and destroying it (Figs. 115, 116). Other natural enemies are the larvae of certain predaceous flies, and the larvae and adults of lady-beetles. The little wasp-like parasite first mentioned, how- ever, is the one that keeps the ' green bug ' in control in normal years, and in years when the latter is most abundant finally over- comes it, as was the case in 1907 in Kansas, North CaroHna, and other States in the more northern part of the range of the pest." Fig. 113. — Lysiphlebus testaceipes Cress., adult female and antenna of male — greatly enlarged. (After Webster, U. S. Dept. Agr.) "Unfortunately this parasitic wasp — as with the other bene- ficial insects — is active only while the temperature is above 56° F., or at least 10° above that at which the ' green bug ' breeds freely; and herein is the whole secret of the irregular disastrous outbreaks of the ' green bug ' in grain fields. As accounting for the out- break in the year 1907, the ' green bug ' had had a whole winter and the following late spring in which to breed and multiply un- molested, and it accomplished its principal damage, as in Texas and southern Oklahoma, before the weather was warm enough for the parasite to increase sufficiently to overcome it." INSECTS INJURIOUS TO SMALL GRAINS 155 " As further illustrative of th(^ important bearing of weather conditions, it is found that in the case of the three important out- breaks of this insect, namel}-, for the years 1890, 1901, and 1907, the temperature for the first five months of each of these years, including the latter part of the winter and spring, was above the normal for the winter months and below the normal for the spring months; in other words, warm winters and cold, late springs." '' The little parasitic wasp which is so useful in the control of this pest is native to this country, widely distril)uted, and every year does its work with the ' green bug ' and with other aphides. It is always present in grain fields, as shown by its appearance every year, to war on these pests whenever the weather conditions Fig. 115. — Dead "green bugs," showing hole from whicli the matu- red parasite of Lysiph- lebus emerges. The top figure shows the hd still attached, but pushed back; the bot- tom figure shows the parasite emerging. Enlarged. (After Webster, U. S. Dept. Agr.) Fig. 114. — Lifsiphlebiis parasite in act of depositing eggs in the body of a grain-aphis — much enlarged. (.\fter Webster, U. S. Dept. Agr.) make its breeding and multiplication possible, and its rate of breed- ing is so rapid (there being a generation al^out every ten days) that with a week or two of favorable weather it gains control over its host insects and destroys them." * Extensive experiments were conducted in Kansas in 1907 in importing these parasites from * From F. M. Webster, Circular 93, Bureau of Entomology, U. S. Dept. Agi-. See also Bulletin of the University of Kansas, Vol. IX, No. 2, by S. J. Hunter, The Green Bug and Its Natural Enemies. 156 INSECT PESTS OF FARM, GARDEN AND ORCHARD farther south before they had iDccome abundant in Kansas fields so as to hasten their control of the aphides, but further experi- ments will be necessary before it can ])e determined whether such a method of colonizing the parasites is practically effective or not. Control. — Most important of all methods of control is the aban- donment of the growing of volunteer oats and the destruction of all volunteer oats and wheat in the early fall. Universal experi- FiG. 116. — Parasitized :;reen l)Hiis — onlargoi S. J. Hunter.) (^From ptiotograph, alter ence throughout the injured area shows that relatively little injury occurs where volunteer oats are not grown. Where small spots of grain have been injured by the pest in late winter, which is the way an outbreak usually begins in southern localities, the aphides on these small spots may be killed by spray- ing with 10 per cent kerosene emulsion, or whale-oil soap, 5 pounds to a barrel of water, by covering the spots with straw and burning, or by plowing under the infested spots. Were this generally done before the aphides commence to multiply rapidly, it is entirely possible that widespread injury might be averted. CHAPTER IX. INSECTS INJURIOUS TO CORN The Western Corn Root-worm * Throughout the corn States of the northern Mississippi Val- ley, wherever corn is grown upon the same land it is subject to serious injury by the Western Corn Root-worm, so called because it first became injuri- ous in Missouri and Kansas and gradually spread eastward to Ohio, though not in- jurious south of the Ohio River. Though the life history of the insect has not been entirely determined, the fol- lowing sum m arizes it as observed by Professors S. A, Forbes and F. M. Webster in Illinois and Indiana. The eggs are laid in the earl}' fall, within a few inches of the base of the stalk, and just beneath the surface of the soil. The egg is a dirty white color, oval in shape, and about one-fiftieth inch long. The winter is passed in the egg stage, differing from most nearly related beetles in this, and the eggs hatch in the spring or early summer. At first the larvae eat the small roots entire, but later burrow under the outer layers of the larger roots, causing the stalks on rich loam to * Diabrotica longicornis Say. Family Chrysomelidoe. 157 Fig. 117. — The western corn root -worm: a, beetle; b, larva; c, enlarged leg of same; d, pupa — all enlarged. (After Chittenden, U. S. D. Agr.) 158 INSECT PESTS OF FARM, GARDEN AND ORCHARD be easily blown over, or dwarfing the plant on poorer land so that it produces but small ears. The full-grown larva is nearly white with a brown head, a little less than one-tenth inch long by about one-tenth inch in diameter. Three pairs of short legs are found on the thorax, but otherwise the body appears perfectly smooth to the eye, though finely wrinkled. Before pupation the color becomes slightly darker and the body shortens. Leaving the roots, the larvae then form small oval cells in the soil and in them transform to pupae, from which the adult beetles emerge in a short time. The beetles appear from the middle of July on through August, about two mor ths being required for development after hatching from the egg. The beetles are of a greenish or greenish-yellow color, about one-quarter inch long, and resemble the common striped cucumber-beetle (page 379) in form. They are to be found in the corn-fields feeding upon pollen and silk until the latter becomes dry, and lay their eggs during August and September. The beetles are often found feeding upon various weeds, clover, beans, cucumber and squash vines, and the blossoms of thistle, sunflower and golden rod. Control. — As the larva* feed only on corn, if the corn-field be planted to some other crop, starvation results, and a simple rota- tion in which corn is not allowed on the same land for over two years in succession usually prevents injury, though a field in which injury has occurred should be planted to some other crop at once. It is imprudent to plant corn on fields in which the beetle has been observed feeding in large numbers on clover and weeds during the late fall of the previous year. The liljeral use of manure and fer- tilizers, and thorough cultivation will, of course, be of service in enabling the plants to withstand attack. The Southern Corn Root-worm * Closely related to the last species, but with somewhat different habits, the Southern Corn Root- worm is frequently injurious to corn from Maryland and southern Ohio southward. * Dinhrotica Vl-puncUita Oliv. Family Chrymmelidoe. INSECTS INJURIOUS TO CORN 159 The adult beetle is of a bright green marked with twelve black spots, which have given it the name of 12-Spotted Cucumber- beetle to distinguish it from the Striped Cucumljer-beetle (page 379) , with which it is often associated feeding on cucurbs. It is some- what larger and more robust, than D. longicornis, and is almost omnivorous in its food habits, feeding upon the foliage and flowers of a long list of forage and garden crops, to which it often does Fig. lis. — The southern corn root-worm: a, egg; h, larva; c, work of larva at base of cornstalk; d, pupa; e, beetle — all much enlarged except c. (After Riley.) considerable damage. Beans are frequently injuretl in much the same way as corn and the roots of melons and other cuciirbs are often so riddled Ijy the larvte as to kill the plants. Injury to corn is done by the larvae in the spring, when they feed upon the roots while the corn is but a few inches high, bore into the crown, and boring into the base of the stalk through the young leaves eat out the " bud." The latter injuiy often seems to be more serious to corn than the injury to the roots, and has given the insect the common local name of " bud worm," which is unfortunatel}' applied to several other insects which do similar 160 INSECT PESTS OF FARM, GARDEN AND ORCHARD injury. Larvae have been found attacking wheat, rye, millet and Johnson grass in a similar way, the beetles seeming to be attracted to fields containing Johnson grass before the corn appears, thus injuring such grassy fields more severely. Injury to corn seems to be worse on low, damp spots. Life History. — The beetles hil)ernate over winter and are among the first insects to appear in early spring, appearing by the middle of March in the Southern States. Eggs are laid during April in the Gulf States and from late April to early June in Kentucky and the District of Columbia. The egg is dull yellow^, oval, and about one-fortieth inch long. The eggs are laid singly just beneath the surface of the soil and hatch in from seven to ten days, those laid early in the season recjuiring considera])ly longer. The larva) become full grown and pupate about a month later, the adult beetles of the first generation appearing during May and early June in the Gulf States and in late June and early July in the District of Columliia and Kenturky. Thus the complete life cycle requires from six to nine weeks in the spring. Eggs are laid l)y the first generation of Ijeetles, the larva' l)eing found on the roots of corn from midsummer until fall, when the second generation of beetles is found in October and November in Kentucky. In the Gulf States there are undoubtedly three complete generations, though they have not l^een carefully followed.* The beetles assemble on clover and alfalfa in the late fall, upon which they feed until winter sets in, and often come out and feed during warm spells in January and Febi'uarv in the Soutliern States. Control. — Although rotation of crops will not be as effective in the control of this species as in the case of D. Jongicornis, it will undoubtedh' l^e found of value to avoid planting corn in succession where injury is probaljle. By planting late after the beetles have laid their eggs, injury has been avoided in Georgia. Liberal seed- ing, using ten grains of seed per hill, will give a sufficient stand free from attack, so that by thinning a good stand may be secured. * In the Northorn States, where this species is not a pest of com, but is common on cvicurl)s antl garden plants, there is probably but a single genera- tion with a life history very similar to that of the striped cucumber-beetle, see page 379. INSECTS INJURIOUS TO CORN ' 161 Fields which are well infested with Johnson grass, or other thick- stemmed grasses, should l)e avoided, for as already indicated the beetles will be attracted to them ])(>fore the corn is up. Both on account of the feeding hal^its of the larvae and the migratory habits of the beetles no insecticide treatment commends itself as practicable. The Corn-root Webworm * Injury. — When young corn-plants are seen" to stop growing, become deformed, and to die off in such numbers as to frequently necessitate replanting, upon examination of the roots the injur}' w'll sometimes be found to be due to the work of a small caterpillar. Two or three, very often five or six, and sometimes as many as eight or nine will bo found at the base of a plant al^out an inch below the surface of the soil, and not over -1 to 6 inches from the stalk, usually being in close proximity to it. If each larva is covered with a fine, loose wel), to which cling particles of earth forming a sort of case, it is probal)ly a corn-root webworm. Where the webworms are present in any number tho}^ will often necessitate a second, third, or sometimes a fourth planting, making the corn very late and involving considerable expense. The worms bore into the young stalks just above the ground, frequently cutting them off entirely. Later on the larger stalks are gouged out at or slightly above the surface of the ground, and the larva) burrow into the folded leaves, which when they unfold have several transverse rows of three to five holes. On account of this habit these insects are sometimes known as " budworms." Strong plants will often make a new start and survive the injury, Init remain much behind those not attacked, while most of the weaker plants will decay and rot off. The Moth. — As one walks through pasture or grass land, many little white and yellowish moths are seen flying about on all sides, but quickly disappear as they alight on the grass. "If a single individual be watched more closely, it will be noticed that in alighting upon a blade of grass it quickly rolls its wings * Crambus caliginosellus Clem. Family Crambidce. 162 JXSECT PESTS OF FARM, GARDEN AND ORCHARD very tightly around its body, and hugs up close to the grass so that it is hardly distinguishable from it. Projecting from the head in front is what appears to be a long beak or snout, on account of which these moths are often known as "snout-moths/' but which really con- sists of the palpi or feelers. The " grass-moths," as they are sometimes called, belong to the genus Crambus and include several c o m m o n species, which are marked with silver stripes and bands, as well as golden lines and markings, so that they often present a very handsome appearance. Life History. — These are the pa- rents of the web- worms which do so much injury to the young corn-roots, the principal depre- dators upon corn belonging to the their eggs in grass Fig. 119.— The caliginonellus segment of larva; e, parasite. weD-wonn {Cramhufi b, pupa; c, moth; full grown about harvest time when they gt) into winter quarters in the root as above described. Control. — It has been observed that late planted corn is much less injured than that planted early, but as it is more seriously injured by some other pests, < late planting may not be advisable. Where corn has been seriously injured, the- old stalks or butts should be dragged off the field and Fig. 128. — The larger corn stalk-borer. a, female; 6, wings of male; r, pupa — all somewhat enlarged. (.\fter Howard, U. 8. Dept. Agr.) burned late in the fall, thus destroying the over-wintering borers. INSECTS INJURIOUS TO CORN 175 When corn is stripped for fodder, the stalks left standing and the land sown in small grain, the most favorable conditions arc allowed the borers for safely passing the winter and developing into moths which will fly to new fields in the spring. A simple rotation of crops will also lessen injury considerably, as Dr. L. 0. Howard has observ^ed that where fields which had been in corn the previous year were damaged 25 per cent, those planted on sod land were damaged but 10 per cent, though reason- ably close to land which had been in corn. Bill-bugs * Throughout the South and often in the more Northern States, .Canada, and the West the bill-bugs sometimes become serious enemies of young corn-plants. They are called " bill-bugs " on account of the prolongation of the head, termed a bill or snout, peculiar to all the weevils or " snout-beetles," by means of which they are enabled to drill holes in the corn-stalks. Several species belonging to the genus Sphenophorus are commonly injurious to corn. One of these, S. parvidus Gyll., also attacks small grains and timothy, and is therefore known as the Grain Sphenophorus. Another species, S. obscurus Boisd., does considerable injur}- to sugar-cane in Hawaii. The adult beetles are from one-fourth to three-fourths of an inch long, of the form shown in the illustration^ and are of a brown or black color, marked with darker longitudinal ridges on the wing-covers. The larva is a thick fleshy white grub, from one-fourth to five-eighths of an inch long, with a brown head and cervical shield on the first segment, and footless. Life History. — The life histories of the different species are but partially known. S. parvulus hibernates over winter as a beetle, appearing in March and April. The female punctures the stalk of wheat or timothy — oats and barley are also sometimes attacked — a little above the roots, and deposits her egg in the cavity. This is done in May or June or even up to July 1st. The larva? are to be found * Species of Sphenophorus. Family Calandridce. See S. A. Forbes, 23d Report of the State Entomologist of Illinois. 176 INSECT PESTS OF FARM, GARDEN AND ORCHARD during July, becoming full grown and pupating during the latter part of that month. The larvae will eat out quite a cavity in the interior of the stalk or bulb, and then attack the roots, thus often killing a whole clump or stool of small grain or timothy. The pupal stage is passed in a small cell in the earth and lasts from two P'iG. 129. — Sphenophorus ochreus, larva, aduh, and work in roots of Scirpiis. (After F. M. Webster, "Insect Life.") to three weeks, adult beetles emerging from the middle of August to the first of October. One of the most injurious species to corn is S. ochreus Lee. The life history is much the same as that of S. parvulus, though eggs have been found as late as July 30th. The natural food-plant of this species, however, is the common club-rush (Scirpus fluvia- tilis), the roots of which consist of bulbs connected by smaller slender roots. The eggs are deposited in or about the roots of this rush, never having been found on corn. The bulbs of the rush are very hard and oftentimes as large as hens' eggs. In them the INSECTS INJURIOUS TO CORN 177 larvae burrow, becoming full grown and transforming to pupae, from which the adult beetles appear in August and September. When the rush l^ecomes too hard for the beetles they often attack a common reed (Phragmites comtnunis), piercing and splitting Fig. 130. — Sections of sugar-cane showing work of Sphenophorus obscurus: a, larva; b, pupa; c, probable points of oviposition. (.\fter Riley and Howard, " Insect Life.") lengthwise the unfolded terminal leaves, and eating out the suc- culent portions within. The injury to corn is done by the beetles while the corn is still young, feeding upon it in the same manner as do the other species. " Standing with the head downward and the feet embracing the lower part of the stalk," says Dr. Forbes, " they slowly sink the beak into the plant, using the jaws to make 178 INSECT PESTS OF FARM, GARDEN AND ORCHARD the necessary perforation. By moving forward and backward and twisting to the right and left, the beetle will often hollow out a cavity beneath the surface much larger than the superficial injury will indicate." As the lower part of the stalk becomes hardened, they leave it for the terminal portion, and when the ears commence to form the}' often penetrate the husk and gorge out the soft cob. Sometimes the injury thus inflicted is but slight, merely resulting in a puncturing of the leaves when they unfold, these holes being in a series across the leaf resulting from a single puncture when the leaf was folded, and looking much like the work of the corn-root webworm; but when several beetles attack a young plant, they will either kill it outright or so deform the foliage and stalk that no ear will mature. Several other species have also been known to do more or less injury to corn, viz., S. scoparius, placidus, cariosus, sculptilis, and pertinax, but so far as known their habits and injuries are much the same as of those already described. Means of Control. — The control of these pests is rather a diffi- cult task. S. ockreus, as in fact are all of the species, is most injurious on recently cleared swamp-lands, and usually disappears as fast as these lands are drained and cultivated. Planting flax, potatoes, or some crop not attacked by these insects for the first crop will largely prevent so serious injury to a subsequent corn crop. The burning over of grass- and swamp-lands infested with the beetles will also be of considerable value. The Maize Bill-bug * Throughout the Southern States and northward to Kansas there has been more or less serious injury by a bill-bug which has been recognized for many years as Sphenophorus robustus Horn, Recently Dr. F. H. Chittenden has recognized this insect as a new species and Mr. E. O. G. Kelly has published a complete account of its life history, from which the following is taken. As will be seen below this species is known to pass its entire life * Sphenophorus maidis Chittn., see E. O. G. Kelly, Bulletin 95, Part II, Bureau of Entomology, U. S. Dept. Agr. INSECTS INJURIOUS TO CORN 179 history upon the coni-pUint, so that the common name given it appropriately distinguishes it from the other bill-bugs previously mentioned. It has, however, been found feeding and probably breeding in swamp-grass (Tripsacuni dactyloides), which may be its native food plant. Life History. — The eggs were found in southern Kansas during June, laid in punctures made by the female in }'oung corn- plants. These egg punctures are mere slits and do not seem to materially injure the plant. The eggs hatch in from seven to twelve days, and from them emerge small footless, dingy white grubs, with chestnut-l^rown heads, of the appearance shown in Fig. 132. " They at once begin feeding on the tissues of the voung corn at the l)ottom of the egg Fig. 131. — The maize bill-bug {Sphenophorus maidis Chittn.) — four tinges natural size. (After Kehy, U. S. Dept. Agr.) puncture, directing their burrow inward and downward into the tap- root. When they finish eating the tender parts of the taproot they direct their feeding upwartl, con- tinuing until full grown, allowing thelower portion of the burrow to catch the frass and excrement. This burrowing of the taproot of the young growing corn-plant is disastrous to the root system; . . . allowing it to die or become more or less dwarfed." Often the young larvae burrow into the heart of the plant and cut off the growing bud, thus killing the top. The larvae become full grown early in August, when they are about four-fifths of an inch long. '' The lar\'ip, on finishing their growth, descend to the lower part of the burrow, to the crown of the taproot, cutting the pith of the cornstalk into fine shreds, with which they construct a cell where they inclose themselves for pupation." The pupae are to be fountl in these cells in late August and early September, the 180 INSECT PESTS OF FARM, GARDEN AND ORCHARD pupal stage lasting ten to twelve clays. The adults commence to emerge by the middle of August and continue to do so until the middle of September. " Some of them leave the pupal cells, but most of them remain there for hibernation." Those which emerged disappeared and probably hibernated in some dense, coarse grass near by. Those which hibernated in the pupal cells emerged the next spring about the time that young corn was sprouting. The beetles are from two-fifths to three-fifths of an inch long, of a dull shining black color, and sculptured as shown in Fig. 131. " The beetles are rarely observed on account of their Fig. 132. — Larva of the maize bill- bug — twice natural size. (After Kelly, U. S. Dept. Agr.) Fig. 133. — C'om plant sho\\ang the result of attack of the maize bill- bug: a, larval burrow containing pupa in natural position — reduced two-thirds; b, egg-puncture con- taining egg — enlarged. (After Kelly, U. S. Dept. Agr.) quiet habits and because they are covered with mud — a condition which is more or less common among several species of this genus and which is caused by a waxy exudation of the elytra to which the soil adheres. The presence of the adults of this species in a corn- field is made evident by the withering of the top leaves of very INSECTS INJURIOUS TO CORN 181 young corn-plants, the plants having been severely gouged. After the plants grow 10 to 15 inches tall they do not kill them, but gouge out such large cavities in the stalks that they become twisted into all sorts of shapes. The attacked plants sucker pro- fusely, affording the 3'oung, tender growth for the beetles to feed upon, even for many days after the non-infested plants have become hard." Injury seems to be most serious on low land. Injury by this species somewhat resembles that done by the larger corn stalk-borer (Diatraea zeacolella), but is easily distinguished from the work of the other bill-bugs, as the punctures of the latter, which usually form a row or rows of holes in the leaves when they unfold, are not always fatal to the plants. Control. — -Inasmuch as most of the beetles hibernate in the corn stubble, they may ))c readily destroyed by pulling out and Inirning the stuljble. Care must be taken, however, to pull out the taproot, as the stalk will be liable to break above the beetle and leave it in the ground. As the infested stalks have a poor root system, they arc easily pulled. The Corn Ear-worm * Practically the only insect injuring the ears of field-corn and the worst insect pest of sugar-corn, is the ear-worm. In the extreme South it is almost impossible to grow sugar-corn success- fully on account of its injury, while further north it largely reduces the profits of corn grown for the cannery, and destroys a consider- able percentage of the kernels of field-corn. It is a most cosmopol- itan insect, being found throughout the United States and in many parts of the world, and has a long list of food plants, being known as the tomato fruit-worm, tobacco bud-worm, and cotton boll- worm (see pages 304, 234, 254) when attacking these plants, besides which it feeds on beans, peas, and many garden crops and forage plants, such as cowpeas and alfalfa. Life History. — Along the Gulf Coast the first moths appear in April, in the latitude of 33° about the middle of May, and in the latitude of Delaware and Kansas, early in June. * Heliothis obsoleta Fab. Family Noctuidce. 182 INSECT PESTS OF FARM, GARDEN AND ORCHARD The moth is about three-quarters of an inch long with a wing expanse of about If inches and is extremely variable in color and markings. Some are dull olive green while others are yellowish or nearly white and with almost no markings. In the most typical moths the wings are l^ordcred with dark l^ands, the wing veins are black and the fore-wings are spotted with l)lack. Fig. 134. — Corn ear-worms at work. The central cob has lieen attacked l)y a nearly full-grown worm, which has bored through the husk near the middle. The eggs are semispherical in shape, al)out one-fifteenth inch in diameter, light yellowish, antl prettily corrugated with ridges as shown in Fig. 184, Those of the first brood ai'e laid on corn, peas, beans, or whatever food-plants are available, and liatcli in three to five days, depending upon the temperature. The catei'pillars of the first generation often attack corn when about knee-high, feeding in the axils of the tender leaves, so that INSECTS INJURIOUS TO CORN 183 when tlio leaves unroll tluy bear horizontal rows of holes. The caterpillars are exceedingly varial)le in color, being from a light green through rose color and l)rown to almost l)lack, and either Fig. 13.5. — Corn ear-worm. Iln.sk of ear of sugar-corn torn open, showing worms at work on tip and hole through which a full grown worni has left. striped, spotted or perfectly plain. The}- become full grown in about 2^ weeks and are then about 1^ to Ih inches long. When done feeeding the caterpillar burrows 2 to 5 inches into the soil near the base of the plant. A cell is then constructed wdiich runs back to within a half inch of the surface of the soil, so that the 184 INSECT PESTS OF FARM, GARDEN AND ORCHARD moth may readily push off this surface soil and escape. The burrow finished, the larva retires to the bottom of the cell and there molts and enters the pupal stage. The pupa is four-fifths inch long, shining reddish-brown. During the summer the moths emerge about two weeks later, but the last generation in the fall passes the winter in the pupal stage. Thus the complete life cycle from egg to adult moth requires slightly over a month in midsummer, and from six to eight weeks for the spring and fall broods. The second generation of moths appears a])out the middle of July in the latitude of Delaware and Kansas. In the far South the second generation of moths appears when corn is com- ing into silk and tassel, upon which the moths always prefer to lay their eggs. As a result, the caterpillars of the second genera- tion in the South, and the third further North, do serious injury to field-corn, gnawing out the kernels at the tips of the ears, and furnishing favorable conditions for molds to propagate, which do further injury. From 2 to 3 per cent of the corn crop of the country, with a cash value of $30,000,000 to $50,000,000, is thus destroyed by the ear worm annually. The third generation of moths appears the last of August in Delaware and Kansas and gives rise to the third brood of caterpillars, which are there the most destructive brood on field- corn and sugar-corn, frequently causing a loss of from 10 to 50 per cent of the latter crop. The caterpillars become full grown during the latter part of September and change to pupse, which hibernate over winter as already described. In the Gulf States there arc four full broods and along the Gulf Coast there may be five or six, while in the Northern States there are but two generations, with possibly but one in Ontario. Control. — As the pupa? pass the winter in the soil, by all means the most satisfactory and practical means of control is to plow infested land in late fall or during the winter, plowing deeply and harrowing. This will break up the pupal cells, crush some of the pupae, and expose others to the rigors of winter to which most of them will succumb. INSECTS INJURIOUS TO CORN 185 The early planting of field-corn prevents the moths from lay- ing their eggs upon it, as it will have passed the silking stage and other fields which are in silk will be preferred; it being possible to thus reduce the injury by at least a third by early planting. Where the caterpillars of the first generation are working in the unfolding leaves, they are sometimes poisoned with Paris green, mixed with flour or corn meal as used for this pest on tobacco, but as Paris green often burns the foliage powdered arsenate of lead will doubtless be found equally effective with- out burning. CHAPTER X INSECTS INJURIOUS TO STORED GRAINS* The farmer who stores his grain, awaiting a higher price, is sometimes sadly disappointed to find that it has been so riddled by " weevil " that it brings no more than had it l)een sold previously. The term " weevil " is rather a comprehensive one, being commonly applied to almost every ins(^ct inf(\sting stored food- products. Only a few species are commonly injurious in the farm-granary. (jrain-weevils Of these the Granary-weevil f and the Rice-weevil J (Fig. 136), are the most common and widely distributed. Both of these insects have infested grain from the most ancient times, so long, in fact, that the granary-weevil has lost the use of its wings and remains entirely indoors. They are small, brown beetles, from one-eighth to one-sixth of an inch in length, with long snouts which are of great service in boring into the kernels of grain. By means of them the females puncture the grain and then insert an egg in the cavity. The larva hatching from this is without legs, somewhat shorter than the adult, white in color, and of a very robust build, being almost as broad as long. It soon devours the soft interior of the kernel and then changes to a pupa, from which the adult beetle emerges in about six wrecks from the time the egg was laid. Only a single larva inhabits a kernel of wheat, but several * See " Some Insects Injurious to Stored Grains," F. H. Chittenden, Farmers' Bulletin, 45, U. S. Department of Agriculture. f Calandra granaria Linn. X Calandra oryzce Linn. Family Calandridce. 186 INSECTS INJURIOUS TO STORED GRAINS 187 will often be found in that of corn. Not only do the larvcc injure the grain, but the beetles feed upon it, and then hollow out a shelter for themselves within the hull. The beetles are quite long-lived, and thus do considerable damage. The egg- laying period is equally long, and as there are three or four broods in the North and six or more in the South, it has bqpn estimated that the progeny of one pair would amount to 6000 Insects in a single season. Grain-beetles Another beetle very common in the granary, l)ut of cjuite different appearance, is the Saw-tooth(>d (Jrain-l^eetle * (Fig. 137). It is a cosmopolitan pest and is also nearly omnivorous. The beetle is only about one-tenth of an inch long, ver}" much flat- tened, of a dark-l^rown color, and may be easily recognized by the six saw-like teeth on each side of the thorax. The larva is of a dirty-white color, and quite dissimilar from that of the gra- nary weevil. Having six legs to carry it about, it is not satisfied with a single seed, but runs about here and there, nibbling at several. When full grown the larva glues together several grains or fragments into a little case, and inside of this trans- forms to the pupa and then to the beetle. In early spring this life ''' Silvanus surinamensis Linn. Family Cucujidm. Fig. 136. — The grain weevil (Calandra granarin) : a, beetle; b, larva; c, pupa, d, the rice weevil (('. oryza) : jjeetle — all enlarged. (After Chit- tenden; U. S. Dept. Agr.) 188 INSECT PESTS OF FARM, GARDEN AND ORCHARD cycle requires from six to ten weeks, but in summer it is reduced to about twenty-five days. Thus there are from three to six or more generations during a season, according to the latitude. The Red or Square-necked Grain-beetle * is about the same size as the last species, but is of a reddish-brown color, and the thorax is almost square, nearly as broad as the abdomen, and not notched on the sides. It breeds in corn in the field and in the granary, first destroying the germ, so that it is especially Fig. 137. — The saw-toothed grain ])eetle (Silvanus surinamensis): a, adult beetle; b, pupa; c, larva — all enlarged; d, antenna of larva — still more enlarged; d, the red or square-necked grain beetle {Cathartus gemellatus Duv.) (After Chittenden, U. S. Dept. Agr.) injurious to seed-corn. It feeds mostly out of doors, though sometimes infesting the granary. The Foreign Grain-beetle f is of much the same general appearance, but smaller and of a more robust appearance It feeds upon a great variety of stored products as well as grain, but rarely becomes troublesome. The Cadelle % also has the bad habit of first attacking the embryo or germ of the kernel, and going from one kernel to another, thus destroys a large numljer for seed purposes. It possesses, * Cathartus gemellatus Duv. t Cathartus advena Waltl. X Tenebroides maurilanicas Linn. Family TrogosUulce. INSECTS INJURIOUS TO STORED GRAINS 189 however, the good trait of feeding on other injurious grain- insects. The beetle is ol)long, flat, nearly l)la('k, and about one-third of an inch long. The larva is of a whitish color, with a \ V Fig. 138. — TheCadelle (Tenebroides mauritanicus) : a, adult beetle with greatly enlarged antenna above; h, pupa; c, larva — all enlarged. (After Chittenden, U. S. Dept. Agr.) brown head, the thoracic segments are marked with brown, and the abdomen terminates in two dark horny processes. It is a fleshy grub, nearly three-fourths of an inch long when full grown. Flour- and Meal-moths The larv» of several small moths sometimes infest grain in store, but rarely do it serious damage, preferring the softer flour^ meal, and food-products. The most destructive of these is the Mediterranean Flour- 190 INSECT PESTS OF FARM, GARDEN AND ORCHARD moth * (Fig. 139) . This insect was practically unknown until 1877, but during recent years it has occasioned the loss of many thousands of dollars to mill-owners. It occurs throughout Fig. 139. — The Mediterranean flour-moth (Ephestia kuehnictta): a, moth; 6, same from side, resting; c, larva; d, pupa — enlarged; e, abdominal joint of larva — more enlarged; /, larva, dorsal view. (After Chittenden U. S. Dept. Agr.) Fig. 140. — The Indian meal-moth {Plodia inter punctella): a, moth; b, pupa; c, caterpillar; /, same, dorsal view — somewhat enlarged; d, head, and e, first abdominal segment o.f caterpillar — more enlarged. (After Chitten- den, U. S. Dept. Agr.) Europe, and is found in Mexico and Chili. It was first recognized in America in 1SS9, and has since done an increasing amount of damage in California, in New York and Pennsylvania, North Carolina, Alabama, New Mexico, and Colorado, and has become * Ephestia kuehniella Zell. Family Pyralidce. See W. G. Johnson, Appendix 19th Report State Entomologist of Illinois, and F. L. Wa.shburn, Special Report of the State Entomologist of Minnesota on the Mediter- ranean flour-moth. INSECTS INJURIOUS TO STORED GRAINS 191 quite generally distributed. " The caterpillars form cylindrical silken tubes in which they feed, and it is in great part their habit of web-spinning that renders them so injurious where they ol)tain a foothold. Upon attaining full growth the caterpillar leaves its original silken domicile and forms a new web, which becomes a cocoon in which to undergo its transformations to pupa and imago. It is while searching for a suitable place for transforma- tion that the insect is most troublesome. The infested flour becomes felted together and lumpy, the machinery becomes clogged, necessitating frequent and prolonged stoppage, and result^ ing in a short time in the loss of thousands of dollars in large establishments." The life cycle of this insect requires ordinarily about two months, but may be completed in thirty-eight days u n d e r the most favorable condi- tions. The adult moth measures a little less than an inch across the expanded wings. The fore-wings are of a lead- gray color, with transverse black markings, while the hind- wings are dirty whitish, with a darker Ijorder. The Indian Meal-moth * (Fig. 140) larvae resemble those of the grain-beetles in having a special liking for the embryo of wheat-grains. They spin a fine silken web as they go from seed to seed, to which they become attached, and to which is added a large amount of excrement, thus spoiling for food much more grain than is actually injured. The moth has a wing-expanse of an inch; the inner third of the fore-wings being a whitish gray, and the outer portion reddish-l)rown, with a coppery lustr(\ * Plodia inter punctella Hbn. Family PuiulidcB. Fig. 141. — The meal snout-moth (Pyralis farinali^) : a, adult moth; b. larva ;c, pupa in cocoon — twice natural size. (After Chittenden, U. S. D. Agr.) 192 INSECT PESTS OF FARM, GARDEN AND ORCHARD The Meal Snout-moth * (Fig. 141) is of a light brown color, the thorax, base, and tips of the fore-wings being darker brown. The wings expand nearly an inch and are otherwise marked with whitish lines as shown in the figu-re. It is very similar to the last-mentioned species in its habits, constructing long tubes with silk and particles of the food in which it is living. The life- history is completed in about eight weeks, and four generations may oc-cur in a year. The moisture of " heated " grain is most favorable for the development of this pest, and it need not be feared if grain is kept in a clean, dry place. The Angoumois Grain-moth f By far the worst granary pest throughout the South is the " fly-weevil," or Angoumois grain-moth. History. — This insect is an importation from Europe and receives its name from the fact that in 1760 it " was found to swarm in all the wheat-fields and granaries of Angoumois and of the neighbor- ing provinces [of France], the afflicted inhabitants being thereby deprived of their principal staple, and threatened with famine and pestilence from want of wholesome bread." The insect was first noted in this country in North Carolina in 1730, and in 1796 was so abundant as to extinguish a lighted candle when a granary was entered at night. It is essentially a southern insect, being very injurious to stored corn in the (lulf States. Of late years it seems to be moving steadily northward, being reported as injurious in central Pennsylvania and Ohio. Wheat, corn, oats, rye, barley, sorghum-seed, and even cow-peas are subject to injury. Life History. — The injury is not done by the moth, as might be reasonably supposed from the fact that it is the only form of the insect usually- seen, but is done by the small caterpillars which feed within the grain, where they may be found during the winter. The caterpillar eats to the surface of the kernel, but not through it, thus leaving a thin lid which the moth can * Pyralis farinalis Linn. Family Pyralidcc. t Sitotroga cerealella Oliv. Family Gelechiidce. INSECTS INJURIOUS TO STORED GRAINS 193 easily push aside when it comes out in the spring, and then covers itself with a fine silken \Tvh. At this time the caterpillar is usually fully grown and is about one-fifth of an inch long, of a white color, with the head yellowish and harder, and having six jointed legs in front, a series of four pairs of fleshy pro-legs along the middle, and another pair of soft legs at the end of the body. With warm spring weather the caterpillar changes to a pupa and about the time that the Avheat comes into head the adult moth emerges. As soon as it emerges, whether outdoors or in a Fig. 142. — The Angoumois grain-moth (^/to^rof/a ccrcaldln): o, eggs; b, larva at work; c, larva, side view; d, pupa; c, moth; /, same, side view. (After Cliittenden, U. S. Dept. Agr.) barn, the moth at once flies to the grain-field, where the eggs are deposited. The exact time at which the moths emerge varies, but occurs some time late in May or in June. The moths quite closely resemble the clothes-moth often foimd flying about houses. The wings are quite narrow, and when expanded measure about one-half an inch from tip to tip, being of a yellowish or buff color, marked with black. The eggs are laid in the longitudinal channel on the side of the grain. Each female lays from sixty to ninety eggs in lots of about twenty each, one lot thus being about enough to infest the kernels of a head. The eggs hatch in from four to seven days. The young caterpillars are at first very active and soon find tender places and bore into the kernels, leaving 194 INSECT PESTS OF FARM, GARDEN AND ORCHARD almost invisible openings. These caterpillars become full ^ grown in about three weeks, just al)out the time the grain is mature, '^^^ ' il About harvest-time the second brood tA of moths appears. These lay then' ^sij eggs during July, depositing them on >■ the ripe heads if the harvest be a little S delayed, Ijut on the wheat in stack if S harvest is prompt. Usually the flTo^'^^l tS caterpillars hatching from these eggs become full grown and remain in the s"^^ 2 grain over winter, but in warm sea- sons, especially if warm in September or when the pest is unusually abun- dant, a third brood of moths appears early in September. These lay another batch of eggs about the middle of September, depositing them upon the open ends of grain in stack or mow, which thus becomes more infested than that in the centre. In grain stacked outside, the caterpillars of this brood become full grown slowly and remain in the grain over winter, but if in the barn they grow faster and a fourth brood of moths appears about the middle of October, the moths being noticed in threshing. The insects con- tinue to breed within doors all winter as long as any grain remains, though they become sluggish and cease feed- ing during cold weather. The number of broods is entirely dependent upon the latitude and weather conditions; in the South, where they can breed continuously, there l)cing as many as eight in a year. bC •g 'M. H INSECTS INJURIOUS TO STORED GRAINS 195 Corn is frequently attacked, Ijut not until it is ripe and husked, and then but rarely when husked in October and November and stored outdoors in slatted cribs. Seed-corn stored in barns, and in the South in almost any situation, is often badly injured. Aside from the loss in weight, grain when badl}- infested becomes unfit for milling purposes, and will even be refused l)y cattle and horses, which should not be urged to eat it, though hogs and fowls will readily consume it. Remedies. — Dr. J. B. Smith, in an interesting bulletin upon this pest, to which we are indebted for much of the above, advises as follows: " Thresh as soon after harvest as possible, and bulk in tight bins or in good sacks. [By " tight bins " are meant those which will not permit the entrance or exit of the moths.] If the grain is dry when harvested, it may be threshed at once; if not, as soon as it is in good condition. If the sacked grain is infested, there will not be wormy kernels sufficient to heat the grain. The moths cannot make their way out and are stifled. Nothing can come in from outside and the grain remains safe. The threshing itself kills many of the insects and jars and rubs off many of the eggs. If binned, the bins should be tight and the grain should be tested occasionally for any appreciable heating. If it heats per- ceptil)ly, it indicates considerable infestation, and it should be treated with carbon bisulfide at once, used at the rate of one drachm per cubic foot, or 1 pound for 250 cubic feet bin-space." Recent investigations have shown that more l)isulfide will often be necessary. See page 198. Those having wheat unthreshed, whether in stack or mow, should thresh at once, and treat as above directed, except that if much of it is noticed to be wormy, it should be treated with carbon bisulfide at once, as soon as threshed, which if done thoroughly will prevent any further infestation that year. Barns and storehouses should he cleaned up and freed from all loose and scattered grain — chickens will help in this — before April 1st, so that no moths will be allowed to develop and infest the grain in the field. Places where grain has been in shock the pre- vious season should be cleaned up by the aid of chickens. Thus if 190 INSECT PESTS OF FARM, GARDEN AND ORCHARD there is any probability of grain being infested, it should be kept tightly covered in the spring so as not to permit the spread of the moths to the fields. Prevention of " Weevil " Undoubtedly grain-insects can usually be more successfully combated by a proper housing of the grain. No matter how often the insects are destroyed in a granary, if the remainder of the barn is full of dust, sweepings, and refuse, as it generally is, on which the beetles can feed and in which they will breed, and if the gran- ary is not absolutely tight, as soon as the gas passes olT the insects from the barn will again enter the granary, and soon it will be as badly infested as ever. Cleanliness. — " Cleanliness will accomplish much toward the prevention of injury from these pests, the cause of a great propor- tion of injuries in granaries, mills, elevators, and other structures where grain and feed are stored being directly traceal^le to a dis- regard of neatness. Dust, dirt, rubbish, and refuse material con- taining sweepings of grain, flour, and meal are too frequently per- mitted to accumulate and serve as breeding-places for a multitude of injurious insects. " The floors or corners and walls of the l^arn or storehouse should be frequently swept, and all material that has no commer- cial value burned." The Granarij. — " The ideal farmer's granary, from the stand- point of insect ravages, should be built at some distance from other buildings, and the rooms constructed of matched floorings so as to be as near vermin-proof as possible. The doors should fit tightly, closing upon a raljl^et, which may be covered with felt or packing, and the windows covered with frames of wire gauze to pre- vent the passage of insects. The floor, walls, and ceilings should be smooth, so as not to afford any lurking-places for the insects, and it would be well to have them oiled, painted, or whitewashed for further security. A coating of coal-tar has been strongly recom- mended for the latter purpose." " The value of a cool place as a respository of grain has been INSECTS INJl'RIOUS TO STORED GRAINS 197 known of old, and a building in which any artificial heat is cmplo}-cd is undesirable for grain storage. The ' heating ' and fer- mentation of grain, as is well known, is productive of ' weevil,' and this should be prevented b}' avoiding moisture and by ventilation- " The storage of grain in large bulk is to be commended, as the surface layers only are exposed to infestation. This practice is particularly valuable against the moths, which do not penetrate far beneath the surface. Frequent agitation of the grain is also destructive to the moths, as they are unable to extricate them- selves from a large mass, and perish in the attempt. The true granary-weevils (small dark-brown beetles with long curved snouts, similar to the pea-weevil), however, penetrate more deepl}', and although bidking is of value against them, it is not advisable to stir the grain, as it merely distributes them more thoroughlv through the mass." — Chittenden. Destruction of " Weevil " Carbon Bisuljide. — " The simplest, most effective, and most inexpensive remedy for all insects that affect stored grain and other stored products is the bisulfide of carbon, a colorless liquid, with a strong disagreeable odor, which, however, soon passes away." At ordinary temperatures it vaporizes rapidly, forming a heavy gas, which is highly inflammable and a powerful poison. Application. — It may be applied directly to the infested grain or seed without injury to its edibleness or viability by spraying with an ordinary watering-can having a fine rose nozzle. In moderately tight bins it is more effective, however, as it evaporates more slowly and diffuses more evenly, if placed in shallow dishes or pans, or on bits of cloth or cotton waste distributed about on the surface of the grain or infested material. The liquid volatil- izes rapidly, and, being heavier than air, descends and permeates the mass of grain, killing all insects and other vermin present. The bin should then be covered with boards, canvas, or blankets, and allowed to remain at least twenty-four hours. If to be used for seed, it should not be left for over thirty-six hours; but if not, 198 INSECT PESTS OF FARM, GARDEN AND ORCHARD leave it forty-eight hours, which will do it no injury for food. After treating, keep the grain covered to prevent reinfestation. A7yiount to Use. — It was formerly recommended that the l^isul- fide be applied at the rate of 1 to 3 pounds to 100 l^ushels of grain or 1000 cubic feet of open space. Recent experiments, however, have shown the total inadequacy of this dosage. Experiments made by Hinds and Hunter * show that the effectiveness of the gas is in direct proportion to the temperature. Below 60° F. the fumigation is ineffective and inadvisable. A dosage which will kill practically all the weevil at 67° to 70° will kill but 60 to 70 per cent at 60° to 65°. They recommend the use of 5 pounds per 1000 cubic feet where the room or bin is quite tight and the tem- perature is 70° or alDOve. For loose rooms and lower tempera- tures, the dosage must be largely increased and may not be profit- al)le. The above estimates are based upon the grain Ijeing in a cubical shape; if it is spread out shallow, more bisulfide will be necessary. Caution. — "Certain precautions should always bie oljscrved. The vapor of carlion bisulfide is deadly to all forms of animal life if inhaled in sufficient quantity, l)ut there is no danger in inhaling a small amount. The vapor is highly inflammable, but with proper care that no fire of any kind, as, for example, a lighted cigar, lantern, or light of any kind, be brought into the vicinity until the fumes have entirely passed away, no trouble will be experienced." Hydrocyanic Acid Gas. — Mills and storehouses which needed treatment were formerly fumigated with carbon bisulfide, which is still employed to a considerable extent, l^ut this has been largely replaced by fumigation with hydrocyanic acid gas, which obviates the risk from fire. Directions for the use of this gas should be obtained from the entomologist of the State experiment station or from the Bureau of Entomology of the U. S. Depart- ment of Agriculture. Sulfur Fumes. — Professor R. I. Smith (l.c) has made experi- * Hinds and Hunter, Journal of Economic Entomology, Vol. Ill, p. 47: R. I. Smith, Bulletin 203, N. C. Agr. Exp. Sta. INSECTS INJURIOUS TO STORED GRAINS 199 nients with sulfur dioxid; produced by burning sulfur slightly wet with alcohol, and finds that it will effectively kill grain insects but injures the germinating power of the grain. " It was found that the fumes produced by burning 2J pounds of sulfur either in a moist or dry atmosphere of 1000 cubic feet space, for twenty hours, would kill all exposed adult insects and practically all the young stages in the grain, but that this also destroyed its germinat- ing power. . . While this treatment cannot be recommended for general fumigation, there is no doubt of its being the easiest and cheapest method of fumigating corn cribs, granaries and similar places whenever they arc being cleaned out and freed of insects in preparation for the reception of more grain." Heat. — The heating of grain was one of the earliest means known of comlmting grain insects, but has been little used in this countr}'. Recently, however, Mr. Geo. A. Dean of the Kansas Agricultural Experiment Station,* has shown that by super- heating mills they may be rid of insect pests much more quickly and cheapl}' than ]\\- fumigation, and with no risk from fire, or from cyanide poisoning. His experiments show that if the temperature surrounding an insect be maintained above 120° F., with a normal amount of moisture, that in a very few minutes it will be killed. This promises to become one of the most prac- ticable methods of cleaning mills and may be used for small quantities of grain, wlu^re there are facilities for heating it or placing it in a superheated room, but probably carbon bisulfide fumigation will be- found more practicable for small amounts. * Geo. A. Dean, Journal of Economic Entomology, Vol. IV, p. 142. CHAPTER XI INSECTS INJURIOUS TO CLOVER * The Clover Root-borer j The clover root-borer is practically the onty insect pest which seriously injures clover roots. It has long been known as a clover pest in Europe, but was first noticed in this country in Fig. 144.— The clover root-ljorer {Hylastinufi obscurus): a, adult, natural size at right ; b, larva or grul); c, pupa — much enlarged. (After Webster, U. S. Dept. Agr.) western New York in 1876, whence it has spread southward to West Virginia and westward to Illinois and southern Michigan, and has also ])een injurious in Oregon. Life History. — During the winter the beetles may l:)e found hibernating in their ]:)urrows in infested clover roots. They are not readily distinguishal)le, for the}' are scarcely one-eighth inch long, and are of a reddish-brown color much like that of the burrow. With the warmer weather of spring they commence * See The Insect Pests of Clover and Alfalfa, J. W. Folsom, 25th Report of the State Entomologist of Illinois, p.p. 41-124. t Hylastinus ohscuni-'i Marsham. Family Scoly(id(g. 200 INSECTS INJURIOUS TO CLOVER 201 burrowing and feeding in the roots, and during late May and early June the females deposit their eggs along the sides of the tunnels. " The female gouges out a shallow cavity, more often in the crown of the plant, sometimes at the sides of the root even 2 or 3 inches below the crown, and in this places, singly, but not far separated, about a half dozen pale whitish, elliptical, very minute eggs. These hatch in about a week, and the larvie for a time feed in the excavation made by the mother, but soon burrow dow^nward into the root, and before the i^st of August, the majority of them have l^ecome full-grown, and passed into the pupal stage. By Octoljcr nearly all have become fully developed beetles, but they make no attempt to leave the plant until the following spring." The spread of the insect occurs very largely in the spring when the beetles fly from field to field, seeking uninfested plants in which to perpetuate their kind. It has been observed that alsike clover is not so badly injured as the mammoth and common red clover, on account of the fibrous roots and the tendency of its tap-root to divide. In Europe alfalfa is injured, but no injury has yet been reported to that crop in this country, though it may be anticipated. '' While an infested clover plant sooner or later succumbs to an attack b}- this insect, life may be lengthened or shortened by meteorological conditions. Thus, if the spring or early summer is very dry, the plants begin to dry in patches late in June, as soon as the hay crop is removed; but if there is much rain dur- FiG. 145. — Clover root, showing work of clover root - borer. Slightly enlarged. (After Webster, U. S. D. Agr.) 202 INSECT PESTS OF FARM, GARDEN AND ORCHARD ing this period, the weakened plants may continue to live until winter, dying out before spring. In either case the farmer is likely to be misled and attribute the loss to the weather."* Clover is practically exempt from attack the first year as the roots are not large enough to accommodate the insects, and it is not until the second year that the plants are destroyed. Control. — The only effective moans of control suggested is summer following as soon as the hay crop has been removed. The field should then be plowed up at once, before the larvae have transformed to pupa?, so that the hot sun, and dry winds, will dry out the roots of the clover and thus starve the larva^, thereby preventing their developing and migrating to other •fields. Clover fields should not be allowed to stand over two years in infested localities. No injury seems to be done in pastures. A system of rotation in which the crop is mowed for hay and seed the first year, and pastured and then broken up the second year, should keep the pest under control. The Clover Stem-borer f Early in June one frequently finds the beetles of the Clover Stem-borer here and there in the clover- field. They are slen- tler, shining beetles, about one-third of an inch long, with a red head and thorax and l)Iuish-black w i n g - covers. The beetles themselves seem to do little or no harm. Hibernating over winter, they lay eggs Fig. 146. — Clover stem-borer (Languria mozardi): the eggs natural size and magnified, the beetle, larva, and pupa — all much enlarged, and above, a clover-stem with the larva at work in it. (After C'omstock.) * Quotations from F. M. Webster, The Clover-root Borer, Circular 119, Bureau of Entomology, U. S. Dept. Agr. f Languria mozardi Fab. Family Erotylidce. INSECTS INJURIOUS TO CLOVER 203 in the pith of the stems early in June, and the larva emerging from these feed upon the pith of the stem, often very seriously weakening or killing it. The larvae become full- grown in a short time, transform to pupce, and the beetles appear by August. Clover- is only one of a dozen food-plants of this insect, which is widely distributed. It rarely does any considerable injury where clover is regularly cut in early summer and fall, and need not be feared when this is not neglected. The Clover Leaf -weevil * The clover leaf-weevil is a stout, oval l)oetle, about one-third inch long, with a long, thick snout. It is of a brownish color, with several narrow gray lines above and Ijroad gray stripes on each side, and with twenty rows of small, deep punctures on the wing-covers. It is also a native of Europe and made its first appearance in the same section of western New York as the last species, about 1S