TECHNICAL BULLETIN NO. 86 AUGUST, 1929 UNITED STATES DEPARTMENT OF AGRICULTURE WASHINGTON. D. C. IMPORTED INSECT ENEMIES OF THE GIPSY MOTH AND THE BROWN-TAIL MOTH By A. F. BURGESS, Principal Entomologist, in Charge, and S. S. GROSSMAN, Senior Entomologist, Gipsy Moth and Brown-Tail Moth Investigations, Bureau of Ento- mology CONTENTS Page Page Introduction 1 Foreign enemies of the gipsy moth not pos- Life history and habits of the gipsy moth, itively established. 88 Porthetria dispar Linnaeus 3 Larval parasites 88 Eggs.. 3 Apanteles porthetriae Muesebeck 88 Larvae 4 Apantelea Hparidis Bouché 95 Pupae -, .. 4 MeteoTua japonicua Ashmead 103 Adults 4 MeteoTus pulchricornia Wesmael 103 Life history and habits of the brown-tail Hyposoterspp 104 jDoth,Nyçmia phaeoTThofa Donovan. 5 Campoplex sp 104 Eggs 6 PhoTOcera agilia Robineau-Desvoidy. 104 Larvae 6 Tachina larvarum Linnaeus HI Pupae ,.- _ 6 Lydella nigripes Fallen 113 Adults __ _-_ 6 Sturmia inconapicua Meigen 113 Introduction of the gipsy moth and the Trickolyga aegregata Rondan! 114 brown-tail moth and the early work against Carcelia aeparata Rondani 114 these pests 6 Ztnillia libatrix Panzer 115 The abundance and spread of the gipsy moth Croaaocosmia sericariae Coronalia 115 and the brown-tail moth from 1905 to 1927_ 7 Pupal parasites. _. _ 116 Early foreign work 10 iirachyiiuria intermedia (Nees) 116 Recent foreign work 11 Jirachyrneria obacurata (Walker) _ 118 Receiving and handling the foreign material Enemies of the caterpillars and pupae.-. 118 al the gipsy-moth laboratory _ _ 19 Caloaoma inquiaitor Linnaeus _ 118 Handling of multibrooded tachinids 18 Xylodrepa guadripunctata Schreber... 119 Handling of single-brooded tachinids 20 Ilabrocarabua latua Dej., var. ffouçeleti Handling of hymenopterous larval para- Reiche 119 sites 21 Foreign enemies of the brown-tail moth posi- Handling of egg parasites.. 22 tively established 120 Handling of predacious l)eetles 22 Larval parasites _ 120 Foreign insect enemies of the gipsy moth Apantelea lacteicolor Viereck.. 120 positively established 22 MeteoTua versicolor Wasmael 127 Egg parasites 23 Sturmia nidicola TowiLsend 131 Anaatatua diaparis Ruschka 23 Compailura concinnata Meigen 134 Scheditui Jfcwana« Howard 31 Carcelia laiifrona Villeneuve. 136 Larval parasites _ 38 Pupal parasites 138 Apantflea melanoscelua Ratieburg... 38 Euj^eromalua nidulana Foerster.... 138 HypoiottT diaparia Viereck _ _ _ 49 Total colonization of gipsy and brown-tall Compailura concinnata Meigen 52 moth parasites und predators 142 Sturmia aaitellata Robineau-Desvoidy 67 Natural mortality of the gipsy moth and Enemies of caterpillars and pupj» 77 brown-tail moth in New England due to Monodontomerua aereua Walker 77 causes other than the imported insect Caloioma ¡j/cophanta Linnaeus 80 enem Íes 143 Conclusion 144 Literature cited , 145 INTRODUCTION More than twenty years have elapsed since active work was begun to import from their native homes and Hberate in the United States the parasites and natural enemies of the gipsj^ moth, Porthetria dispar Linnaeus,T: ^JJJ j^jjg brown-tail moth, Nygmia phaeorrhoea Donovan. 1781 •—29 1 2 TECHNICAL BULLETIN 86, U. S. DEPT. OF AGRICULTURE At the time this work was initiated, many of the towns in eastern Massachusetts within a radius of 30 miles of Boston were swarming with caterpillars of these insects, and hundreds of thousands of acres of forests, as well as most of the parks and residential sections of the cities and towns, were overrun with these pests. To make con- ditions far more serious, there were known to be vigorous colonies of these insects throughout southeastern New Hampshire and in York County, Me., in Providence, R. I., and in the towns surrounding. The statements of multitudes of citizens who suffered material loss as well as personal inconvenience were fully as emphati-c as were those of the entomologists who were called upon to review the situation and to attempt some measure of relief from the ever-increasing hordes of these pests. For a few years hand-control measures, although vigor- ously applied, resulted in little relief, except in limited areas where the most intensive work was done, and completely defoliated areas in late June and July bore witness to the dangers which threatened the tree growth of New England. The idea of bringing to this country the natural ene:nies of these pests was hailed with enthusiasm, and hope was frequently expressed that speedy relief would result. In 1911 a report on this work was published by Howard and Fisk m)', which reviewed the efforts made and the results obtained up to that time. This attempt to introduce parasites and natural enemies to con- trol two closely related foreign pests was the largest in scope that had ever been planned and executed, and no appreciable relief was evi- dent at the time this report was published. The gipsy and brown- tail moths had continued to spread and enormous areas were defoli- ated each year in outlying territory, in spite of the fact that some of the most promising parasites had begun to obtain a foothold and that intensive control work had been undertaken by all the States con- cerned and by the Federal Government. The difficulties of securing parasites and of establishing them suc- cessfully in a new country were not fidly realized at the time the work began, and the period which was required to make even a slight reduction in the swarms of their fecuncl hosts could not be estimated. Many of the basic facts relating to the habits of the beneficial species which it was sought to introduce, as well as to the proper methods for the handling and successfid transportation of these delicate and insome cases minute species, were to be learned by years of constant experi- ment and study. Furthermore, the popular idea that a single species of parasite might suffice in effecting control proved to be fallacious for this does not happen in the native homes of these two pests. The difficulties of the problem were further enhanced and the final results were somewhat clouded because of the fact that in many countries in Europe, as well as in northern Africa and Japan where parasites are present and are periodically effective, there are periods when the hosts become excessively abundant. The work on the introduction and colonization of natural enemies has been continued even more intensively since the bulletin cited was published, and it is being pushed at the present time. As the years passed by, more knowledge was obtained by experience and from ' Reference is nude by italic numbers in parentheses to "Literature cited," p. 1«. PLATE Tech. Bul. 86, U. S. Dept. of Agriculture 1 DIFFERENT STAGES OF THE GIPSY MOTH (PORTHETRIA DISPAR) Eng mass OQ neuter ut twi^; ti:nia!e moth just below ; feiuaUi moth, Japanese variety, lower left ; male raoth ¡iiimedifttely above; ieniale moth inimedialely abovi-; male moth with wiii^îs foMeii, upper lel't ; iiialethrvsaUsat r'iglit of ill is; female chrysalis a^airi at rij-lil ; larva at <*iiter. All alxiiit foui-fiflhs natural size. (lioward and Kisket GIPSY MOTH AND JBBOWN-TAIL &IOTH INSECT ENEMIES 3 experimental work, and it is the purpose of this bulletin to review bnefly the results obtained.^ In order that the relation of the imported parasites to their hosts may be understood, a brief description of the life history and habits of the gipsy moth and the brown-tail moth is given. LIFE HISTORY AND HABITS OF THE GIPSY MOTH, PORTHETRIA DISPAR LINNAEUS EGGS During 9 or 10 months of the year the gipsy moth is in its egg stage (fig. 1). Most of the eggs are laid during July, although some are Fid. l.~Liie cycle of the gipsy moth not laid mitil August. They are laid in layers protected by bufT- colored hairs from the abdomen of the female as shown in the lower ' DurinK the progress of the work on gipsy moth and hrown-tail moth parasites hundreds, perhaps thou.san<is, of men nave assisted in making ixxs-sible the resuits set forth. They inciude not oiiiy the men directly employed in this work at tlie gipsy-motli ialM)ratory at Mi'tras*' liighlan<ls, .Mass., l»ut a liost of other .'^tate, (lovernment, and town olficials, as weil as many citizens whos«' suggestions and information concerning local conditions have Un-n invaluable. Entomologists and other officiais in many foreign lands have afforded every help within their i>ower antl many of the eml>a.ssies and <'onsuls of the United .states in foreign countries, and the I'nited .States Dispatch agent in New York City, have smrHithe«! the way for foreign investigations an<i made possible the c3t[>editious dispatch and delivery of shipments of parasites when time was the vital factor and when a slight diday might nave meant the death of the delicate material in the shipments and the {>ossible failure of an entire season's work. To all who have assisted Ibis work in any capacity grateful acknowledgement Is extended. 4 TECHNICAL BULLETIN 86, U. S. DEPT. OF AGRICULTURE right comer of Plate 1. The number of eggs varies considerably, but averages from 300 to 400 for each cluster. They are deposited on the tree trunks and on the under sides of the branches. Sometimes they are found on the leaves and often on a great variety of objects on the ground near trees. Hatching starts in the spring when the new leaves begin to appear, which is usually during the first two weeks of May. It continues over a period of several weeks, but the height of hatching occurs within a week. LARVAE Newly hatched caterpillars measure only 3.5 millimeters in length. They feed on the leaf hairs and later perforate the opening leaves.