140 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
many caterpillars upon which the eggs had actually hatched, but 
from winch no parasites were reared. 
That this explanation may serve in part to elucidate the mystery 
is also true, but still later observations have shown conclusively 
that the parasite larva? may gain entrance into their host and yet 
fail to mature. Two explanations have grown where one was deemed 
sufficient, as the result of certain technical studies which have been 
made at the laboratory during the past year. Mr. P. H. Timberlake 
and, later, Mr. W. R. Thompson have thoroughly demonstrated the 
fact that a parasite larva gaining lodgment in an unsuitable host 
may die, and its body may be in great part absorbed through action 
of the phagocytes without causing the host obvious inconvenience. 
This very likely takes place with Tachina mella in its relations with 
the gipsy moth and is probably a better explanation of its failure to 
become an elective parasite than any other which has yet been put 
forward. 
Mr. Thompson also discovered another most remarkable and 
peculiar phenomenon in connection with parasitism by those tachi- 
nids the larvae of which inhabit integumental funnels similar in 
character to those formed by Tachina. These funnels appear to be 
formed as a direct result of the tendency of the skin to grow over 
and heal the wound caused by the entrance of the tachinid maggot 
into the body of the host. This wound is kept open by the larva 
itself, and as a result the growing integument takes the form of an 
inverted funnel, more or less completely surrounding the parasitic 
maggot, which continues to breathe through the minute orifice in its 
apex. When the caterpillar molts the old skin is usually torn away 
from around this opening, leaving the maggot in situ and unaffected, 
but occasionally its attachment to the funnel may remain so strong 
as to result disastrously for the maggot, and the whole funnel, maggot 
included, may be withdrawn. Thus, not merely the eggs may be 
molted off, but the internal feeding maggots which have hatched 
from the eggs may be molted out and perish. 
ACH^TONEURA FRENCHII WlLL. 
A very few specimens of this species have been reared from time 
to lime in the course of the work at the laboratory. It is probable 
that the species is synonymous with that mentioned by Forbush 
and Fernald under the name of Achsetoneura fernaldi. 
EXORISTA B LAN DA 0. S. 
Occasionally reared as a parasite of the gipsy moth. 
