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- 
si lip 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 Par 
a- known their earlier stages are absolutely indistinguishable. 
Dexodes was firsl received and liberated as a parasite of the brown- 
t;nl moth in 1906, and it was the first of the tachinid parasites to be 
cariied through all of its transformations in the laboratory upon Amer- 
