22 
bent in an angle. This end is immersed into a little cluster of a 
secretion, by means of which the egg is attached to the host. As 
a rule the fiy deposites its eggs on the hairs of the host, but 
sometimes also on the skin"). 
At the time of oviposition the embryo of Carcelia gnava is 
at a very little advanced stage of development, neither the tracheal 
system, the spines or the pharyngeal skeleton could be observed. 
The hatched maggot moves about on the host and penetrates into 
it through a hole which is produced in its skin. In its first stage 
the maggot lives free inside the host, but the maggots in 2” and 
3' stages are connected with the integument of the host by means 
of a chitinous funnel, which originates in most cases from a mem- 
brane between two segments of the host. 
In the case of Stilpnotia sacilis the fly deposites its eggs both 
on younger and elder caterpillars. Corresponding to the size of 
the host from one to four parasites can develop. The colour of 
the markings, which is white in normal caterpillars, is turned into 
a yellow colour in the infested specimens. The younger infested 
caterpillars do not moult anymore, but fasten themselwes, when they 
are dying, to a branch or a leaf by means of their suckers, and 
the emptied skins remain for a long time on the trees. The full 
grown infested caterpillars make a very rudimentary spin. The 
larval skin bearsts on the foreend, and the pupa begins to emerge; 
at this time, however, the host is killed by the parasites.. These 
pupæ are very easily recognized by their strange form. In some 
rarer cases I found the parasites in fully developed pupæ. 
In the case of Malacosoma neustria I have only found the 
parasites in full grown caterpillars, and that in spite of the fact 
1) In this connection I think a short mention of another tachinid egg, 
which I have found on the hairs of a caterpillar of Acronycta meny- 
anthidis, may be of some interest. The dimensions of the egg were 
0.50—0.25 mm., the upperside was rather strongly curved and the 
lower side which was attached to a hair of the caterpillar quite flat. 
om was not reared and beside the egg I only know the first 
in which the pharyngeal skeleton shows the most striking 
sandt radke to that of the maggot of Carcelia gnava 
