' Circular No. 9) I UHJH I oited States Department of Agricu BUREAU OP ENTOMOLOGY, L. O. HOWAK1) KntomologUt »nd Chief..! Bw THE BAGWORH. (TTtyridopUryx tphemei 11. iu By l 0. I fott uuj and I II Cbittkndi m i: \\ \rri\i;\Mi \m- NATUB1 "i kTTACK. Shade tret-, -hrui>-. and hedges, and in particular evergreens, are much Bubject to injury by a medium sized caterpillar which ha- a curious habit <>t' crawling about <>n the infested trees in a bag-like case, whence its common name of bagwormor basket worm. In the shelter <>(' these cases the insects undergo all their transformations, after which the bags remain attached to the plant- for some time and are conspic- uous objects on leafless trees and shrubs in late autumn mill in winter. Like the tussock moth and the tall webworm* tin- species i- preeminently a pest on the Btreets and in park- and private grounds <>!' cities and towns and is even more subject to fluctuation in num- bers. It i-. however, more limited in distribution and nut found a- a rule north of southern New York and the central portions of Pennsylvania and Ohio. South of these points it i- in certain years very trou- blesome and tin- subject of much complaint Such a year was 1907, when the bagworm attracted greater attention than any other tree defoliator. Numerous complaints were received of injuries in the region mentioned, and especially from the State- of New Jersey, Pennsylvania, Maryland. Virginia, West Virginia, Ohio, Indiana, and Illinoi-. d"he natural enemies of thi- insect (see p. »'•> were comparatively scarce, and there i- a strong possibility of a recur- rence of injuries in the year- to come. The general appearance of the bagworm i- shown in figure I. which illustrates the caterpillar when nearly full grown, in it- characteristic bag. When removed from it- bag it look- a- shown in figure 8, • '. which represents the larva H maturity. A4~tlu- period in it- develop- I •. I — Rac« ..mi ( Thyriilnplrryl Natural - tor i: lerocnmp 18. A A. - -Cir. 97—08 1 ment it may attain a length of about three-fourths of an inch. The body is soft in texture and dull brownish or blackish, while the head and thoracic Begments arc horny and whitish, mottled with dark brown. ORIGINAL HOME AM) PRESENT DISTRIBUTION. The bagworm is unquestionably native to North America. It abounds in the Southern States, and its proper home— that is to say, the part of the country where it reaches its maximum — is in the Lower Austral life zone. It extends thl'OU'gh a considerable portion of the Upper Austral zone, hut there are indications that it has gradual!}' spread into this territory from more southern regions." The shade trees of Baltimore. Washington, St. Louis, and other more southern cities are frequently defoliated by this insect. Northward it occurs Kn.. -. — Bagworm ( Thyridopteryxephemerstformia} : a, Fall-grown larva: /<. head of same: c, male pupa; • /, female pupa; e, adult female; /, adult male. All enlarged (from Howard . through New Jersey and at many points in Pennsylvania, including the cities of Harrisburg, Elliottsburg, Allentown, and Swarthmore. Farther west it has been found at Columbus, Marietta, South Salem, and other localities in Ohio, at several points in West Virginia, at Brooklyn, Ind.,in Pecatonica, ThompsonviUe, and Allendale. 111., and so on west to Oklahoma. Everywhere south of these localities, except in the immediate Gulf region, it abounds. In the East it is commonly found in New York City and Brooklyn, and at several points on Long Island. In the Hudson River Valley region it has been recorded by Felt at Yonkers and Mount Vernon, and has been collected at New " In the main the bagworm is one of those characteristic forms like the wheel-bug [Arilus cristatus Jj.) , the Carolina mantis [Stagmomantis Carolina L.), and the la' g stage within the old female bags, and for this reason hand-picking in winter time is an efficacious remedy. In the late spring the young hatch from the eggs, crawl out upon the twigs, make their way to the nearest leaf, and immediately begin to feed and to construct cases or bags for themselves. They spin a large amount of silk and attach to it, for additional strength and protection, bits of leaf or of twig, evidently attempting to disguise the nature of the case as well as to strengthen it. The larva i- remarkably soft-bodied, except for its head and strong thoracic plates, and it is necessary that the soft abdomen should have some protection. The construction of the bag of an allied species was carefully studied by H. G. Hubbard, and it is a very interesting performance. The young larva (tig. 4, ut it- head and slow ly walk- off. A- tin- caterpillar grows tin' case i- constantly enlarged, bits of twigs and any ot her small objects being used to ornament the outside, and these objects will vary w itli the kind of tree 14)011 w li i c li the caterpillar i- feed i n g. While the Ian a is small it carries it- case erect, t>ut \\ hen it i- larger the case hangs dow n ( fig. 1 1. The larval skin is cast four times, and during the molting the mouth of the bag is kept closed w ith silk. There is a small opening in the extremity of the hat: through which excre- ment and cast skins are pushed. The male bags are smaller than those of the female-, reaching a length of about an inch, while those of the females are much larger. Toward the end of August, about Wash- ington, I>. ('.. the larva complete- it- growth, attache- it- bag firmly by a silken band to a twig, strengthens it inside with an additional layer >>i -ilk. and within this retreat, which now becomes its COOOOn, transforms to pupa with its head downward. The pupal period lasts about three week-, and then the imago emerges. The male chrysalis work- it- way out of the lower opening, and the winged moth issues -Cir. '.<7-(is 2 Pic 1 a Newly hatched bagworui before makli ast beginnii • nearly com- plel larva hi 1 it lir-t molt Highly 1 through the cracking skin, leaving the chrysalis hanging from the bag, as shown at c, figure ">. The chrysalis of the female docs not push its way at all out of the bag, but the skin cracks and the female gradually works her way partly out, her head reaching the lower end of the bag, (lig. 5, d). The males fly about, seeking the hags of the females, and when one is found in which the head of the female is near the end. showing that she has emerged from her chrysalis >kin. the male pushes his enormously protrusive and, in fact, telescopic genital apparatus up into the bag to the anal end of the female and fertilizes her. The female then works her way back into the chrysalis skin, gradually filling it with eggs until more than half of it is filled, scattering in among the eggs some of the sparse hairs from her body. Having done this she forces her shriveled body out of the open- ing, falls to the ground, and dies. The eggs re- main in this way until the following spring, when they hatch, as previously described. There is thus only one generation annually. Note. — There is a possi- bility that the bags of this extremely common insert might be made commer- cially useful. Itssilk, from a practical standpoint, has always been ignored, but it is firmer and stronger and more easily spun as carded silk than that of must other native silk cocoons. Fig. 6.— Bagworm at (a, h. c) successive stages of growth, bag; •/. female bag. Natural size i from Howard I. Male NATURAL ENEMIES. Although apparently well protected from the attacks of birds b}' its tough case, the bagworm is somewhat extensively parasitized by several forms of ichneumon and chalcis Hies, most of them species which affect also similar tree-feeding caterpillars. Prominent among these is the common Pimpla inquisitor Say (fig. 6), which, however. more commonly parasitizes the tussock moth and tent caterpillars. The related P. conquisitor Say is also a parasite of the bagworm and a third species of ichneumon, Allocota ( II< mitt les) thyridopU rigis Riley (tig. 7), is usually the most abundant of all. Four or live individuals of this species comnionlj' infest a single bagworm, spinning for them- selves white silken cocoons within the bag. fCir. 97 " Malacosoma spp. The species last mentioned was for manj years credited with being a primary parasite of the bagworm, although recenl observations would indicate that it is a secondary parasite when infesting other Kr. • male, from Pro, l.—AUc M ii henlaiged caterpillars. This mighl be explained by the hypothesis that this parasite oviposits onlj in cocoons or cases of firm texture, and there fore can not be the primary parasite of an insect w bicb is not provided with a case of t liat character. <^K Certain chalcis flies also breed in the bags of tin- insect. These include Sjnlochalcls maria Riley Mi;.'. B), Chalets ovata Saj (fig. 9), and the common little Dibrachya boucheanus Rate. (fig. 10). Tin- last i- a hyperparasite, in the case of the i>avr- worm probably secondary, ami in the case <>t' other cater] rpillar • 8 tertiary parasite. Habrocytits thyridopterigi* Ashm. (fig. 11) is assumed to be a tertiary parasite on Allocdta thyridopterigis Riley, when the latter is a secondary parasite of the tussock moth, but may be secondary when breeding in the cases of the bagworm. REMEDIES. Fig. 10. — Dibrachys boucheanus: Adult female and antenna of male. Much enlarged (from Howard). When the bagworm occurs upon deciduous trees it can be controlled by hand-picking the bags in the winter, but when it affects evergreen trees it is practi- cally impossible to apply this remedy with profit unless the plants arc badly defoliated. There- fore for the treat- ment of evergreens spraying is a neces- sity. The methods of controlling shade- tree pests in cities and towns, as out- lined in Farmers' Bulletin No. 99, a on pages 25-29, are in part applicable to this species. This bulletin should be read by persons who have experienced trouble from the depredations of the bagworm. Collecting the bags. — -?• One of the most important remedies consists in gath- ering the bags with the contained insect by hand and either burning them or preserving them to lib- erate the useful parasites which have been previ- ously mentioned. This work may be facilitated by the use of a 12-foot pole pruner or similar appliance, and can be intrusted to those ordinarily unemployed, such a- children and aged persons. Where the trees are very tajl it will be necessary to use a long ladder. For best results the cooperation of neighbors who are troubled with the same pest should be secured. « This publication nuty be had gratis on application to the Department of Agriculture. [Cir. 97] Fig. 11. -Habrocytus thyridopterigis. How ard i. Greatly enlarged (from 9 Ycr\ considerable immunitj from future injury will result bj care In the employment of this method. It is particularly useful where on Ij a few trees arc infested. The bags are Mich conspicuous objects on defoliated or bare trees in w inter thai it i- not at all difficult to detect them, l>ni in cases where comparatively fe^ insects are presenl on evergreen trees 1 1 •« ■ \ are not so easily seen. Encouraging ttu parasite*. When many trees are infested it is advisable i<> keep the hand picked bags for a considerable time in receptacles, such as barrels covered with netting, preferably of wire, bo that the numerous beneficial parasites of tin- pest will be able to issue in the spring and assist In the control of the bagworm the fol lowing rear. One or two holes bored in the bottom of the barrel or i»o\ will prevent water from accumulating and drowning the insects. Where the bags can be placed in piles in an open -pace or inclosure distant from trees and free from disturbance, the young insects, having very limited powers of locomotion, will soon perish of starvation, as they will not be able t<> reach the trees or shrubs after they batch. Spratffng with arsenicals. ( )m evergreen, where the bags are more or less difficult to find, band-picking can not be advised. A striking instance < > t" the futility of this method under such circumstances was given by Prof. ('. V. Rilej in hi- testimony at a conference <>n the gipsy moth in 1891. He said that he once trie. I to protect a cedar tree not more than »; feet high, upon his own grounds at Washington, i>\ hand-picking. lie worked tin- two consecutive months picking "H small bags from that tree, the progeny of not more than two female-. Almost daily he went to the tree and found fresh specimens which he had overlooked the day before. For evergreen tree-, therefore, an arsenical spray is the best remedy, [n connection with the Btory of hi- experience just related, Professor Riley stated that he had abso lutely -topped injury by the bagworm on large tree- in the Smith SOnian grounds by -pray inc. and in the summer of L895 we had a similar experience on the grounds of the Agricultural Department at Washington. Tree- sprayed with Paris green at the rate of l pound to 150 gallons of water were completely rid of larva? of the bagworms. It i- easier to reach the bagworms on evergreen than on large-leaved deciduous -hade tree-, -uch a- maple and elm. but if carefully carried out spraying will result in the destruction of the bagworms, so that the collection of the bags in winter will riot he necessary. Arsenate of lead at the rate ^i l pound of the prepared paste f"iin t.> from !'•'> to 50 gallons of water will lie found even more useful than the Paris green, as it- greater adhesiveness renders it less likely to he washed off by rains, which in some seasons frequently occur almost daily at the time when the larv;e are beginning to work. fCir. 97] 10 The best time to apply the arsenical is when the egg* hatch, or shortly afterwards, and the best methods of spraying shade trees are disclosed in Farmers' Bulletin No. !'!». Approved: James Wilson, Secrt tary of . Igricultun . Washington, D. ('.. December®, 1UQ7. [Cir. 97] O UNIVERSITY OF FLORIDA 3 1262 09216 5306