4 9i 6 ' /* t/f*'' U. S. DEPARTMENT OE AGRICULTURE, BUREAU OF ENTOMOLOGY— BULLETIN No. 127, Part I. L. O. HOWARD, Entomologist and Chief of Bureau. PAPERS ON INSECTS AFFECTING VEGETABLE AND TRUCK CROPS. THE SPOTTED BEET WEBWOKM. BY F. H. CHITTENDEN, Sc. D., In < 'harge of Truck ( rop and Stored Product Insect Investigations. Issued May 31, 1913 WASHINGTON: GOVERNMENT PRINTING OFFICE. 1913. BUREAU OF ENTOMOLOGY. L. O. Howaku, Entomologist and Chief of Bureau. C. L. Marlatt, Entomologist and Acting Chief in Absence of Chief. R. S. Clifton, Executive Assistant. W. F. Tastet, Chief Clerk. F. H. Chittenden, in charge of truckcropand stored product insect investigation*. A. D. Hopkins, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. F. M. Webster, in charge of cereal and forage insect investigations. A. L. Quaintance, in charge of deciduous fruit insert investigations. E. F. Phillips, in charge of bee culture. D. M. Rogers, in charge of preventing spread of moths, field work. Rolla P. Currie, in charge of editorial work. Mabel Colcord. in charge of library. Truck Crop and Stored Product Insect Investigations. F. H. Chittenden, in charge. C. H. Popenoe. Wm. B. Parker, M. M. High, H. (). Marsh. John E. Graf, Fred A. Johnston, D. E. Fink. C. F. Stahl, A. B. Duckett, entomological assistants. I. J. Condit. R. S. Yaile, collaborators in California. Henry N. Ord, collaborator in Oregon. Thos. H. Jones, collaborator in Porto Rico. Marion T. Van Horn. Pauline M. Johnson, Anita M. Ballinger. Cecilia Sisco. preparators. ii CONTENTS. Page. Introductory • I Descriptive 1 The moth 1 The egg 2 The larva 3 Distribution 3 Notes on occurrence 4 Attack on beets and chard 4 Injury to ornamental plants 5 Other records and notes 6 Associated insects 7 The yellow-necked flea-beetle (Disonycha mellicollis Say ) 7 The spinach flea-beetle (Disonycha xanlhomehena Dalm. ) 8 The Hawaiian beet webworm (Ilymenia fascial is Cram.) 9 Natural enemies 9 Control 10 Bibliography 11 ILLUSTRATIONS. PLATES. Page. Plate I. Swiss chard injured by the spotted beet webworm (Ilymenia perspec- talis) 4 II. Sugar beets showing injury from combined attack of spotted beet webworm and spinach flea-beetle 4 III. Swiss chard in same row as shown in Plate I, not attacked by the spotted beet webworm. but showing mild attack by the spinach flea-beet le 4 IV. Fig. 1. — Male and female moths of the spotted beet webworm. Fig. 2. — Moth of the Hawaiian beet webworm ( IIym< n in fascialis) 8 TEXT FIGURES. Fn.. 1. The spotted beet webworm (Ilymenia perspectalisr. Moth, larva and details 2 2. The Hawaiian beet webworm (Ilymenia fascialis): Wing venation, show- ing characters of genus; head and antenna 3 3. The spotted beet webworm (Ilymenia perspectalis): External male characters 3 7S051°— 13 HI Digitized by the Internet Archive in 2012 with funding from University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation http://archive.org/details/inse14unit V. S. P. A., R. E. Bui. 127. Part I. T. C. & S. P. I. I., May 31, 1013. PAPERS ON INSECTS AFFECTING VEGETABLE AND TRUCK CHOPS. THE SPOTTED BEET WEBWORM. {Hymema perspectalis Hiitra.) Ry F. H. Chittenden, Sc. D.. /// Charge of Truck Crop and Stored Product Insect Investigations. INTRODUCTORY. The spotted beet webworm (Hymenia perspectcMs Hiibn.) has at- tracted the writer's attention on two occasions from its occurrence on beets in the District of Columbia. It is a singular fact that it was first observed in 1905 and that its presence did not again become no- ticeable until after a lapse of seven years, or until 1912, when it became a veritable pest. It may be classified both as an enemy to sugar beet, because of its occurrence on that plant normally, and as an insect injurious to ornamental plants in both the garden and greenhouse. The larva is at first sight rather plain, but on closer examination it is seen to be distinctly and beautifully marked. The moth is also a most beautiful creature and has often been found flying about the District of Columbia. The food plants which will be mentioned in the present paper probably do not by any means exhaust the list. DESCRIPTIVE. THE MOTH. Hymenia perspectalis is a member of the family Pyralidse and sub- family Pyraustina\ according to Dr. Dyar's classification. It has been described under various synonyms as follows: Spoladia animalis (iuen.. S. exportcilis Guen.. Zinckenia primordialis Zell., Desmia rhinthonalia Walw., and Hymema pharsiusalis Walk. The genus (under the name Zinckenia) is characterized by Sir GeoBge Hampson as follows: Palpi upturned, the 2nd joint broadly scaled in front and not reaching vertex of head, the 3rd well developed and acuminate; maxillary palpi long and fili- form ; frons rounded; antennae of male nearly simple, the base of shaft excised, 1 2 INSECTS AFFECTING VEGETABLE AND TRUCK CROPS. and a tuft of hair [rising] from basal joint : tibia? with the spurs long and Dearly equal. Fore wing with veins 3, 4. 5 from angle of cell; 7 well separated from 8, 0, to which 10 is approximated. Hind wing with vein 3 from angle of cell; 4. .J approximated for a short distance: 0. 7 from upper angle, 7 anastomosing with 8. THE EGG. The egg was not seen by the writer owing to the lateness of the season when continuous work was begun. We therefore have t<» depend npon the description furnished by Mr. Davis. He writes, in substance, that the female deposits her eggs flat and singlv on the stem of the plant near the base. The egg is oval. 0..'»7 nun. by 0.82 mm., and being transparent pale green is quite conspicuous on the plant. Its surface is slightly convex and covered with microscopical, irregular polygonal areas appearing as a netlike sculpture on the surface. Walker's description of the species under the name phrasixsalis follows : Female. Brown, rather slender, whitish beneath. Palpi vertical, slightly curved, rising higher than the head: second joint slightly fringed; third lanceolate, about half the length of the second. Pectus pure white in front. Abdomen extending a little beyond the hind wings; hind borders of the segments white. Fore legs with brown bands. Wings moderately broad, with a cupreous tinge; markings white; fringe here and there white. Fore wings with the interior line slender, nearly straight; exterior line much interrupted, broad and regular in front: reniform mark represented by a trans- verse subquadrate spot. Hind wings with the exterior line broad, complete, attenuated hindward. Length of the body 4 lines; of the wings ft lines. Fig. 1. — The spotted beet webworm [Hffmenia pcr- spcctalisi: a, Moth; b, larva, lateral view: r, larva, dorsal view, showing characteristic mark ings on head and joints : ^r3 °*' tn * s l arva wa€B extended is about 20 mm. ' ■ / u\ l% Itoa\ When at rest, or retracted, it is considerabty less. The width at the widest portion is about •2..") mm. The pupa, unfortunately, was not preserved. Fin. 2. — Venation of Hymenia fas- ciulifi, showing characters of t lie mnus: head and antenna, lateral view, at right. (After Hampson.) PIG. 3. — E x t e r n a 1 male characters of moth of II linn i' in pi rspectalis. Great- ly enlarged. (Orig- inal, i DISTRIBUTION. tialian regions. The distribution accorded this species by Hamp- son is '• Xearctic. Xeotropical.-Ethiopian. and Aus- Nothing is known of the origin of the species, and it is uncertain whether it comes from the Old or the Xew World, but it is obviously exotic and introduced into the United States. As the known species are from Africa, this may indicate the original habitat. The species is not known in Europe, but it will probably in time become cosmopolitan. 4 INSECTS AFFECTING VEGETABLE AND TRUCK CROPS. The record of injurious occurrences includes only Brooklyn. X. Y.. and Washington, D. C. Undoubtedly the .species occurs in trouble? some numbers in many localities, but no records are available. Through the kindness of Dr. H. G. Dyar and from other sources I am enabled to furnish the folio-wing distribution: Washington, D. C. October 1, is?!). Kansas. September, 1*72. Ohio. Georgia, A] nil. 1879. Hurricane Mills. Tenn. (G. G. Ainslie). Brownsville, Tex. (McMillan). Tryon, N. C, July 3, 1904 | W. F. Fiske i . Dallas. Tex. (Boll). Texas ( Bel f rage). Miami. Fla. (Schaus). Peruauibuco, Brazil (Koebele). Oaxaca. Mexico. Grenada, British West Indies. St. Lucia, British West Indies Guatemala (Cockerell). Costa Rica i Schaus). Panama (Busck i. Venezuela. French Guiana. Peru. Bio de Janeiro. Brazil. Newark, N. J. Cuba. Sarawak, Borneo. Central America. NOTES ON OCCURRENCE. ATTACK OX BEETS AND CHARD. October 1, 1005. the writer first observed this species in a small colony on sugar beets growing in the insectary garden connected with the Bureau of Entomology. The insect was studied at that time with sufficient care to enable a drawing of the larva to be made, which is presented herewith. The moth, however, was not reared because of an accident which occurred to the rearing jar in the writer's absence. September 30. 1012. after a lapse of seven years, this same species was again detected by the writer and readily recognized from the drawing previously made. It was first noticed and caused consider- able injury on Swiss chard growing in the grounds of the Bureau of Entomology. The infestation covered one-half of a row of chard, where the damage was practically complete. Injury, however, was complicated by another insect with which it was associated, the spin- ach or beet flea-beetle (Disonycha xanthomeloena Dalm.). which had been injurious to the same plants in an earlier and a later generation and was still at work throughout the time that the lepidopterous larva was observed, and even later. The work of both species is illus- trated in Plates I and II. while Plate III shows, for comparison, a chard plant which has been slightly infested but not injured. The huge holes were made chiefly by the beetles earlier in the season, and the blacker portions show where the larva 1 or caterpillars did their greatest damage. From the outset of attack it was noticed that larva- were rarely seen during the daytime and evidently were nocturnal or practically Bui. 127, Part I, Bureau of Entomology, U. S. Dept. of Agnc iltun Plate I. B.I. 127, Part I, Bureau of Entomology, U. S. Dept. of Agriculture. Plate II 27, Part I, Bureau of Entomology, U. S. Dept. of Ag-iculture. Plate 111. "^ ■ mjL-JK • i 1 ^B ' » W MMmM } *% v\\1vkK?i'- • ■ 1 £^ ^t\ Jw?^. Lx" ' ^» • ... r ■' " % '^3 <£ m i r"fc» H*. *> vr^A *^ THE SPOTTED BEET WEBWORM. 5 so. and that they concealed themselves about the bases of the plants near the roots and under portions of leaves or petioles which rested on the "•round. This was especially noticeable at the time when the larva were attaining their full growth. Subsequently, October '■). the writer, with Mr. A. B. Ducket t, found larva 1 of this species at work on table and sugar beets. On the sugar beet- similar injury to that on Swiss chard had been done, but for some reason the larvae were scarce. The work was quite apparent. however. On the table beets the larva 1 looked considerably darker, due to the darker food plant on which they fed. They were ob- served at this time in all stages of growth from the first stages of the larva to the last stage. The location of the chard and table and sugar beets had much to do with the growth of the larva, the sun playing an. important part. On a single leaf of sugar beet taken October 4 the larva remained in the same position for about -2-1 hours. The leaf was small, and after this period, after capture, only slight growth of the larva could he observed, especially in the case of the younger stages. These latter were probably in the second stage. They were very nearly white, showing very feeble markings. They measure about ;?..") mm. in length. In what appears to be the third stage the larva assume decided markings, but are not nearly so dark as in the next stage. They are decidedly green in color, and measure about 10 mm. in length. In the last stage the larvae, just before pupating, turn pale and somewhat yellowish. The cocoon is formed in different ways — on the plant and on the ground — and is covered with more or less webbing, and sometimes with an abundance of black excrement which naturallv soon grows dry. INJURY TO ORNAMENTAL PLANTS. On October (>. 1012. the writer observed at Iowa Circle. Washing- ton. D. C.. severe injury to foliage plants of the order Amaranthacea?. The most seriously injured area was a large circle in one of the beds at the west end of the park. The plants were practical^ ruined, merely hanging together in shreds. Opportunity did not offer to ob- tain the larva because of the crowd of pedestrians and others seated in the immediate vicinity. On another plat where the plants did not receive nearly so full sunlight the larva were found in more abun- dance, but only half as much injury had been accomplished. It is plain that the first lot had mostly matured and the second lot were near maturity. The plant in question, on which the insects were most abundant, was Telanthera versicolor, or the Alternanthera of florists. b INSECTS AFFECTING VEGETABLE AND TRUCK CROPS. There were also beds of the Achyranthes acuminata of florists, known botanically as Iresine Undent, which were slightly injured by this pest. It was noticed that the larva?, as in the case of attack to other low-growing plants, rest chiefly during the daytime on the lower leaves and near the roots. ( )ctober 7 the writer observed much injury to several plats of Alter- nanthera on the grounds of the Department of Agriculture, but lar\ Be were difficult to obtain until the much injured lower leaves were noticed; then no trouble was experienced, Mr. Duckett easily taking about a dozen. In this case, as in others, with the exception of that at Iowa Circle, colonies of the spinach flea-beetle {JHsonycha xantho- melama. Dalm.) were present and had been responsible for the early injury. AVhen first collected the two species were in the proportion of five of the flea-beetle to two of the webworm, but later the lepidop- terous larvae were found to be doing the greatest damage, A few young larvae were observed at this time. Cut leaves of beets and refuse stems were placed near the affected Swiss chard as decoys, with the result that many larvae were found, some within the stems and some of them on the side nearest the ground. Many were also found on and under leaves 1 which had withered. Larva? which transformed to pupa 1 October 1 emerged as moths October 25, or in 21 days. Larva? which transformed to pupae Octo- ber 12 emerged on October 30, or in 18' days. One which pupated October 1G emerged October 31. or in 15 days, showing the length of the last generation of the season to vary between 15 and 21 days, ac- cording to temperature. None of the moths which were kept for the purpose deposited eggs, nor did any remain over as larva-, as in the case of many related species in hibernation. Hence it is doubtful if this species really hibernates in the District of Columbia, and it may be that the region is reached by moths which fly from more southern places in warm days in spring or early summer. At any rate injury has never been noticed until the autumn. One moth was captured by the writer as late as December 10 in the insectary. It might have emerged from the plants there or obtained access to the building from the outside. OTHER RECORDS AND NOTES. The foregoing records have been made from the writer's personal observations. In looking over the notes of the Bureau of Ento- mology a much earlier record was found, dated April 1, 1896, when Mr. Theodore Pergande noticed large numbers of the moth flitting about in the propagating house of the Department of Agriculture 1 This habit of concealment on the dried leaves is a very common one among both beeUes and caterpillars. Disonycha i-ant homeland was observed in similar locations, even on dried leaves growing high on the plants. THE SPOTTED BEET WEBWOBM. 7 and was told by the gardener that this moth evidently belonged to a small larva which w;is doing great damage to the leaves of several varieties of Alternanthera grown in boxes and pots in the green- house. It was also observed that the larva' worked mainly at night and that they concealed themselves during the daytime between the roots (if these plants at the bottom of the pot. November 27, 1909, Dr. II. T. Fernald sent specimens of this spe~ cies for identification that had been received from Cuba. November 15, 1910, Mr. D. K. McMillan, while working under the writer's direction at Brownsville. Tex., collected the larvae of this species on Amaranthus and beets in that vicinity. The larva 1 were attacking the leaves and flowers of both plants and webbing the leaves and stems. Moths were very numerous on December G of the same year, a few larva 1 still being found on the food plants men- tioned. Parasites were reared from larva 1 taken November 15. April 11. 1912, Prof. Glenn W. Herrick, of Cornell University, Ithaca. N. Y.. sent specimens of the moth with report that they were reared from larva* found very abundantly in a greenhouse in Brook- lyn. N. Y.. and that they were especially bad on Alternanthera. Mr. John June Davis has forestalled the writer in publishing an article on this same species, which he terms the Alternanthera worm. He records that in 1910 this species was found eating the foliage of the variegated border plant Alternanthera. and states, what the writer has also noted, that if the larva* are numerous enough to attract at- tention they usually defoliate the plant repeatedly as new shoots and leaves put forth, thus ruining it for ornamental purposes and sometimes killing it. The article includes descriptive matter, notes on habits, and suggestions as to remedial measures, among which arsenicals, hand picking, and light traps are especially mentioned. ASSOCIATED INSECTS. THE YELLOW-XECKEI) FLEA-IVEETLE. 1 (Diaonycka mellieollis Say.) October 8. 1912, the writer observed, in a badly infested plat not previously examined in Iowa Circle. Washington City, about 20 indi- viduals of the yellow-necked flea-beetle {Disonycha meUicollis Say) congregated in a space of less than a square foot. They were in a warm place, the sunlight was strong, and hence they could all have escaped, though they could have been captured that evening. The writer captured enough specimens to be sure of the species, although this insect can be readily separated from xanthamelcena in life some- iSee also Bui. 82, Pt. II. Bur. Ent., I". S. Dept. Agr., pp. 2V»-:".J, 1909. 8 INSECTS AFFECTING VEGETABLE AND TBUCK CROPS. what better than in dried specimens. It is singular that this park should have been so badly infested by this species, while only one individual could be found in a long search on the grounds of the Department of Agriculture. The difference in distance is not more than 1J miles. THE SPINACH FLEA-BEETLE. (Disonyclia xanthomelcena D;ilm.) During the year 1912 beets as well as spinach grew very rapidly in the District of Columbia during rainy days, succeeded by wanner ones, but owing to press of other work the writer was unable to give them and their insect enemies as much personal attention as thev deserved, and another reason was that the species involved, Disonycha xanthomelcena Dalm., has already been written up with considerable care. Nevertheless there is always something new to learn, as there will be of all species, as long as we continue to observe them under dif- ferent environments and atmospheric conditions. The table beets grew so rapidly that in spite of the larva 1 and adults of the spinach flea -beetle, which " peppered them full of holes," they made consid- erable progress. The spinach began to die rapidly about the beginning of the third week of June, and in four days nearly every plant appeared as if dying. In addition to the spinach flea-beetle, the spinach aphis (RhopaZosi- phum dianthi or Myzus persicce auct.) was also present, but, as affirmed by Dr. Erwin F. Smith, who, with the writer, examined the plants June 25, there was no evidence of disease or of malnutri- tion. If the plat of spinach had been a field, the plants would un- doubtedly have perished, owing to the combined attack of the flea- beetles and the aphides, and this in spite of the fact that the aphides were being rapidly destroyed by ladybirds. To determine the extent or degree of injury, comparison was made of a beet root taken from our experimental plat, which had been very little affected by this flea-beetle, with another lot which had been badly affected, with the result that it required nine of the affected roots to equal the weight of one that was practically unaffected. The small roots were picked out at random by the writer from the place most badly affected, which was at the sunny end of the plat. It should be mentioned in this connection that plants growing where they were shaded by hedge plants were comparatively little affected by insects. This same observation has been made in connec- tion with the imported cabbage caterpillar (Pontia rapce L.), which is not disturbed by wasps when feeding in shady places. Bui. 127, Part I, Bureau of Entomology, U. S Dcpt. of Agriculture. Plate IV. Fig. 1.— Moths of the Spotted Beet Webworm (Hymenia perspectalis 1 , male above and female below. much Enlarged. (Original.) Fig. 2.— Moth of the Hawaiian Beet Webworm (Hymenia fascialis). Much Enlarged. (After Marsh.) THE SPOTTED BEET WEBWORM. 9 Evidently this and other species of flea-beetles, or at least many of them, are in the habit of feeding to some extent in sunshine as well as in shade. In regard to remedies for the spinach flea-l>eetle. while conducting some experiments in July, 1912. F. H. O'Neill, student assistant. spraying tor cabbage butterflies and honey bees. 1 to see if sweetened and poisoned substances would kill any of them, observed that a mixture of arsenate of lead used at the rate of C, 12, and 25 pounds, and similar amounts of molasses, to 100 gallons of water, did not destroy the butterflies or bees, but about GO dead individuals of this flea -beetle were counted beneath the radishes July 1G. The flea- beetles were not in particular evidence during these days; but they had " peppered " the beets with the usual small holes and must, therefore, have been abundant about the roots of the plants and come up to feed on the leaves, to their very swift undoing. It was not expected that the poison would kill either the butterflies or the honey bees which were present, and these were practically all unharmed. THE HAWAIIAN BEET WEBWORM. (Hymcnia fascialis Cram.) In a single instance the Hawaiian beet webworm (Hymenia fascia- lis Cram.) was reared from Swiss chard with the spotted webAvorm at Washington. D. C Moths issued on October 7. The chard is a new food plant. The species is recorded by Marsh as attacking table and sugar beets, stock beets or mangel-wurzels, and several species of Amaranthus, Euxolus, purslane (Portidaca oleracea), cucumbers, and chenopodiaceous weeds. The moths of the two species are shown, for comparison, in Plate IV. NATURAL ENEMIES. On several occasions during October the last two stages of the nymph of the spined soldier-bug {Podisus maeuliventris Say) were observed attacking the larva? of the spotted beet webworm. This was the only predaceous insect observed, although there are probably several others. The same is true of the parasitic enemies, a single one being noticed, a small braconid, Hemiteles sp. (Chttn. No. 2194°). This latter was reared October 7. The very closely-related Hymenia fascialis has several parasites, and the probabilities are that if the present species were studied more carefully in other regions a number of other natural enemies would 1 These experiments were made at the request of correspondents. 10 INSECTS AFFECTINc; VEGETABLE AND TRUCK CROPS. be discovered. Undoubtedly also wasps of the genus Polistes, be- sidea Limneriwm kawaMense Cram.. Chelowus blackburni Cram., and Cremastus hymema Vier., enemies of II. fascidlis in Hawaii, will attack this species in its larval condition. CONTROL. It is obvious from the notes on the occurrence of this insect that injury was discovered too late for the application of insecticides. In practically every case the larvae were in the last stage, the few younger larva' merely indicating the exception to the rule. Such being the case it was not possible to test any remedies whatever. It is inter- esting to relate, however, in the case of Swiss chard, that many of the plants, being able to withstand a considerable degree of cold, re- covered and put forth new leaves, practically a second crop of leaves developing, and that the moths hatched from all larvae and did not deposit eggs, at least not in confinement. What they would do under natural conditions is not quite certain for this latitude. In the case of the related Hawaiian beet webworm, Mr. H. O. Marsh has demonstrated that Paris green applied at the rate of 2 pounds in 100 gallons of water did not burn beet foliage, and the same would be true of chard and the ornamental plants which this species attacks. Whale-oil soap at the rate of 8 pounds to 100 gallons of water is added, and serves as an effective adhesive agent or " sticker." thus enabling a more even distribution of the poison over the leaf surfaces. In addition to Paris green. Mr. Marsh demonstrated that nicotine sulphate, used at the rate of 1 fluid ounce to 4 ounces of whale-oil soap and I gallons of water, sprayed upon cabbage, resulted in the destruction of other small and larger larvae. He expresses the belief also, reasoning from analogy, that this formula, although not actually tested on Hymenia larvae, woidd probably prove entirely effective. Arsenate of lead and arsenite of zinc should both be tested for this insect should it occur in numbers and an opportunity be afforded for an early application of these j^oisons as sprays. The most important item in the control of this insect is the detection of injury early in the season, before actual damage is accomplished. Among other remedies fall plowing should be practiced. It is unwise to grow susceptible plants in the same locality in which this insect has been abundant the previous season. There is no proof as yet that as far north as the District of Colum- bia this species will in the near future renew attack or Income as bad a pest as in 1912. The possibility exists, however, and a close look- out will be kept for its reappearance. THE SPOTTED BEET WEBWOHM. 11 BIBLIOGRAPHY. 1. Hubnkr. Jacob.— Sekmett. Eur., Pyr., fig. 101, 179<>. (Not seen.) 2. Zki.i.ku. P. C. — Lep. Microptera In Caffrorum