274 
PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
illustrations of the lengths to which she would go in satisfying her 
crude and unreasoning instincts. She would oviposit with as much 
apparent freedom upon a dead and decomposing caterpillar, or the 
fragment of skin torn from such a one, as upon a living caterpillar. 
Quite an extensive series of experiments was to have been made to 
determine the lengths to which she would go, but these experiments 
were discontinued after a time because there hardly seemed to be 
any limit beyond the purely physical. .No Pteromalus was ever 
induced to oviposit in any tachinid puparium, nor in any other 
insect protected by a hard shell, but almost any small, inactive, and 
soft-bodied insect, especially if it were inclosed in a thin silken web 
or cocoon, and provided it was in the near vicinity of caterpillars of 
the brown-tail moth or of their webs, would be attacked and usually 
Fig. 66.— Pteromalus egregius: Female in the act of oviposition through the silken envelope containing 
hibernating caterpillars of the brown-tail moth. Greatly enlarged. (Original.) 
without hesitation. The cocoons of small Hymenoptera, such as 
Apanteles and Limnerium, were especially attractive, and would be 
attacked whether associated with the brown-tail moth or not. 
The results of this indiscriminate oviposition were very varied. 
Eggs deposited upon dead caterpillars of the brown-tail moth inva- 
riably perished except in one instance, in which the caterpillars were 
freshly killed and "pasteurized." Upon this occasion a small pro- 
portion of the larvae lived, and at least one went through to maturity. 
Upon active caterpillars of the brown-tail moth and even upon inactive 
caterpillars removed from the silken envelopes with which they 
surround themselves within their nests, oviposition was never suc- 
cessful if the caterpillar moved to any extent afterwards. Even the 
hibernating caterpillars, removed from their nests, will move about 
