TACHIXID PARASITES OF THE GIPSY MOTH. 
219 
In its method of attack Compsilura is the opposite of Blepharipa. 
It-, egga hatch in the uterus of the mother, and the tin}' magots are 
deposited beneath tlie skin of the host caterpillar by means of a 
sharp, curved "larvipositor," winch is situated beneath the abdomen. 
They usually seek the alimentary canal, in the walls of which they 
establish themselves during the first stage of their larval existence. 
Growth is rapid, and in the summer is in no way correlated with 
the growth and development of the host. About two weeks are 
required for the complete development of the maggot, irrespective 
of the stage of the host at the time of attack, and at the end of that 
period it issues, and usually drops to the ground for pupation. The 
puparia from maggots which issue from caterpillars which have spun 
for pupation are nol infrequently found in the cocoons in the case of 
the brown-tail moth; 
and even in the case 
of the gipsj moth, 
winch does not spin 
cocoons w orthy of the 
name, the puparia are 
often found immedi- 
ately associated with 
the host remains. 
It requires a sur- 
prisingly short time 
for the females to at- 
tain full sexual matur- 
ity after their emer- 
gence, three or four 
days apparently being 
sufficient. This, with 
two weeks for the 
growth of the larva, and one week, or perhaps a little more, for the 
pupal period, makes possible a generation every four weeks during 
the warmer months of the \ ear. 
The position of the larva in the alimentary canal, together with 
certain structural characteristics, consisting of minute anal hooks, 
w hich are only know n amongst other first-stage tachinids in the very 
similar genus Dexodes, makes possible the quite accurate determina- 
tion of Compsilura concinnata from its first-stage larva alone, and 
only from observations which have been made upon these larva 1 is 
it possible to say anything definite and at first hand concerning its 
habits of hibernation. Larvae, which are almost certainly Compsi- 
lura concinnata, have been occasionally found in living brown-tail 
moth caterpillars during the winter months. It is presumed if these 
larva 1 were able to mature under these circumstances, that they 
Fir.. 41.— Compsilura concinnata: Adult female and details. Much 
enlarged. (Original.) 
