Sept 15,1924 
Polyscelis modestus GaJian 
295 
provided each time for oviposition. In 
no case did more than one adult emerge 
from a puparium, although in possibly 
10 or more cases more than one egg or 
more than one larva were found within 
a puparium. 
EFFECT OF PARASITE ON HOST 
In its attack upon the host the larva 
of Polyscelis modestus liquefies the con¬ 
tents of the Hessian fly larva as do 
other chalcidoid larvae of the Hessian 
fly parasites which have been studied. 
This process of liquefaction takes place 
rapidly, being almost completed in 24 
hours after the parasite has attacked 
its host. A period of quiescence fol¬ 
lows the attachment of the parasitic 
larva to its host and probably it is 
during this period that a digestive fluid 
which causes disintegration is injected 
by the primary parasitic larva. When 
the internal organs of the host are com¬ 
pletely disintegrated, the liquefied con¬ 
tents are rapidly consumed by the 
parasite. 
SUMMARY 
Polyscelis modestus Gahan, which was 
first discovered in 1915, has thus far 
proved to be a Hessian fly parasite of 
only minor importance. 
Its present known distribution is 
confined to the southeastern and south 
central parts of Pennsylvania and the 
north central part of Maryland. 
It attacks and destroys both the 
larvae and the pupae of the Hessian 
fly, as also the larvae and probably the 
eggs and pupae of its own species. It 
is occasionally hyperparasitic, probably 
on Platygaster vernalis (Myers). 
Females reproducing parthenoge- 
netically are arrhenotokous. 
Before consumption by the parasite 
the internal contents of the host 
undergo a process of liquefaction, 
which probably is caused by the injec¬ 
tion of a secretion by the primary 
parasitic larva. 
99183—25t-3 
