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A STUDY IN HYPERPARASITISM 19 
annually. From 30 to 40 days are required for development from 
ege to adult, in the case of the summer generations. Hibernation 
occurs in the mature larval form, and adults appear about the middle 
of June. 
SPILOCHALCIS TORVINA (CRESSON) 
On a very few occasions the writers have obtained this species from 
cocoons of A. melanoscelus. Its very rare appearance indicates that 
it is of no consequence as an enemy of this Apanteles. Sufficient 
material was not available to permit laboratory studies of its life 
history. 
EUSAYIA DEBILIS (SAY) 
Even less frequently reared than the preceding species, Husayia 
debilis has been of no importance whatever in preventing the increase 
of Apanteles melanoscelus. It is included here merely to record its 
occasional appearance among the hyperparasites attacking that 
primary. 
CALLIMOMIDAE 
MONODONTOMERUS AEREUS WALKER 
This hyperparasite is of major importance as an enemy of certain 
Tachinidae. It appears to attack hymenopterous primary parasites 
much less often, and has been very seldom obtained from cocoons of 
A. melanoscelus collected in the field. It is discussed in some detail 
because of certain interesting traits which it exhibits. 
In the laboratory it has frequently been bred upon Apanteles, as 
well as upon Meteorus and Spilocryptus. There appear to be nor- 
mally two generations annually, but the writers have carried the 
species through the full year with only one generation. The females 
on emerging from their winter quarters are very slow to oviposit. It 
was found by dissection that fully formed eggs do not occur in the 
reproductive system until two or three weeks after emergence. 
Development from egg to adult, however, is very rapid. The eggs 
hatch in about 2 days, and the entire larval period covers only 7 to 
10 days, while the pupal stage is as long as the combined periods 
spent as egg and as larva, or approximately 9 to 13 days. Approxi- 
mately 20 to 25 days are required for development from egg to adult. 
Like most hyperparasitic species, the larvae feed externally upon the 
primary parasite. Usually they are gregarious, several developing 
upon one host. As many as 24 very small adults have been obtained 
from a single field-collected puparium of Compsilura concinnata 
Meig., but usually the number emerging from such puparia ranges 
from 6 to 14. From the much smaller Apanteles cocoons more than 
two adults have rarely been obtained. 
The females of the overwintering generation mate in the early fall 
and hibernate as adults. In several cases females issuing from host 
cocoons or puparia as early as July 15 have been successfully hiber- 
nated. No males have ever been found going over the winter. The 
brown-tail moth seems to have a particular attraction for this species; 
and the winter webs of the hibernating gregarious brown-tail moth 
larvae are used to a considerable extent by the female Monodonto- 
merus for winter quarters. However, at the gipsy-moth laboratory 
there is a record of a specimen having been found hibernating in a 
