1924] 
Th.e Biology of Trichopoda pennipes Fab. 
11 
this point eggs were removed from the body of a bug as soon as 
laid, a moistened camel’s hair brush proving to be excellent for 
this purpose, and were isolated in vials. After twenty^four 
hours the mouth-hooks of each young maggot could be seen 
rasping away at the inner surface of the egg-shell, and in thirty 
hours the larva was found protruding from the hole it had 
scraped in the floor of its prison. Eggs removed from the body 
surfaces of bugs thirty hours after oviposition were found to be 
empty, a hole in the bottom of each, and a corresponding hole 
in the chitin of the host, testifying to the penetration of the 
parasite. 
The Larva. As stated above, the larva, upon hatching, 
penetrates the bottom of the egg-shell and burrows directly 
through the body-wall of the host, regardless of the thickness of 
chitin at that particular point. 
Sufficient dissections of parasitized squash bugs have 
not been made to enable the writer to state accurately the habits 
of the parasite within its host, or the number of larval instars.. 
Individuals of three different instars have been observed, and 
it is probable that there are four in all, as has been stated by 
Townsend (1908, p. 98) for certain other Tachinid parasites. 
Dissections seem to show that the larvae while young live in the 
general body-cavity, no derangement of organs being apparent 
in these dissections. As the larvae approach maturity, however, 
they gradually consume the fat body and those organs contained 
in the abdomen of the host, which was seen to be practically 
hollow in some adult squash bugs from which parasites had just 
emerged. 
Upon the completion of growth, which requires approximate- 
I 3 ' sixteen days, the larva forces its way out at the posterior 
end of the body of the host, which is still alive, and drops to the 
ground. This is not the case with the second generation larvae, 
which appear to remain within the body of the host throughout 
the winter, completing their growth when the latter become 
active in the spring. The host dies within a day or two of the 
emergence of the parasite. Emergence through the side of the 
body, as recorded by Weed and Conradi (1902), has not been 
observed. 
