TACHINID PARASITES OF THE GIPSY MOTH. 931 
Blepharipa, which was colonized in the same locality and under 
the same circumstances and subsequently recovered, does not leave 
its host until after the latter has pupated, and since the collection 
of pupe is very much less difficult than the collection of caterpillars, 
its recovery was that much more easy and certain. Although 
upward of a dozen Blepharipa were secured from collections made 
in this colony, all of them were from pupz and none from the cater- 
pillars, which had to be depended upon for Parasetigena. 
A determined effort will be made to recover both species in 1911, 
and the results of the season are anticipated with much interest. 
CARCELIA GNAVA MEIG. 
This is probably the least understood of the tachinid parasites of 
the gipsy moth. It appears to be not at all well distributed through- 
out Europe and has never appeared in sufficient abundance to give 
it rank as among the important parasites except in the material 
from southern France. From that region it has been secured in 
sufficient numbers to make its colonization possible on a scale that 
is quite as satisfactory as the colonization of Tricholyga, or, for that 
matter, of Compsilura until after Compsilura was found to be estab- 
lished. 
It was received in gipsy-moth caterpillar importations as early as 
1906, but in very small numbers in that year, and in still smaller 
numbers in 1907 and 1908. In 1909 the very large and until then 
unprecedented importations from the Hyéres region produced several 
thousands of flies, and more were received in 1910, which went to 
strengthen colonies of the previous year. Curiously enough, in 1910 
it was almost the only tachinid parasite secured from this region, 
on account of which the gross number colonized is in excess of any 
other species. Like Tachina, Tricholyga, and Compsilura, it is 
practically certain that an alternate host will be a requisite if it is to 
complete its seasonal cycle in America. If this disadvantage can 
be overcome, there is every reason to expect its recovery in 1911 or 
1912. That it was not recovered in 1910, in spite of the fact that 
some 10 ,000 caterpillars of the gipsy moth were collected in the 
eedinis vicinity of the most satisfactorily liberated colony of the 
summer before, entirely loses its significance when it is taken into 
account that neither was Compsilura recovered from these 10,000 
possible hosts, and Compsilura was also colonized at the same time 
and in the same place and under circumstances very much more 
favorable to its establishment than those which accompanied its 
original and effective colonization two or three years before. Better 
than Compsilura has done is expected of none of the tachinids, and 
neither Tricholyga, Carcelia, nor Parasetigena, nor Zygobothria, 
