296 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



their molting webs they crawl down the trunks of the trees, and the 

 cocoons of the parasite are found in splits and holes in the bark, rarely 

 higher than from 1 to 1^ yards from the ground. The host caterpillar 

 is left alive and remains for some time clinging to the cocoons of its 

 parasite, something which has never been observed in the case of A. 

 lacteicolor. 



The plans for the coming season, if they materialize, call for a thor- 

 ough study of the Russian parasitic fauna of the brown-tail moth, and 

 it is sincerely hoped that the observations of Mr. Emelyanoff may be 

 confirmed. 



TACHINID PARASITES. 



Several of the tachinids which attack the brown-tail moth have 

 already been mentioned in the course of the discussion of the gipsy- 

 moth parasites. Among them Compsilura concinnata is the only spe- 

 cies which is of real importance in connection with both hosts. • 



Tachina larvarum is not uncommonly encountered as a brown-tail 

 moth parasite, but never so commonly as it frequently is in its other 

 connection. Tricholyga grandis has also been reared in small numbers 

 from cocoon masses of the brown-tail moth. 



The tachinid parasites of the brown-tail moth, which are either 

 unknown as parasites of the gipsy moth or which are rarely encoun- 

 tered in that connection, include a considerable variety of species, sev- 

 eral of which appear to be of little or no real importance. As will be 

 seen, they include amongst their number species which represent the 

 extreme of diversity in habit. 



Dexodes nigripes Fall. 



Another example of the artificiality of the present accepted scheme 

 of classification of the tachinid flies is to be found in the separated 

 positions therein occupied by the two exceedingly similar species 

 Compsilura concinnata and Dexodes nigripes. So similar are these two 

 that if a few hairs and bristles were to be rubbed from the head of 

 one it would be practically impossible to distinguish it from the other, 

 even though everything in connection with the early stages and life of 

 each was known. The one point of difference of any consequence 

 from an economist's standpoint is the more restricted host relation- 

 ship of Dexodes, which, though equally common with Compsilura as 

 a parasite of the brown-tail moth in Europe, is exceedingly rare as a 

 parasite of the gipsy-moth caterpillars. In every other respect, 

 except host relationship, the habits of the two are identical, and so far 

 as known their earlier stages are absolutely indistinguishable. 



Dexodes was first received and liberated as a parasite of the brown- 

 tail moth in 1906, and it was the first of the tachinid parasites to be 

 carried through all of its transformations in the laboratory upon Amer- 



