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 

 Ap an teles 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 



