262 



PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



parasites known to hibernate within them are believed to be thor- 

 oughly well-established in America, their importation has been dis- 

 continued. 



These parasites, including two which are secondary, number eight 

 species in all, and will be first considered as a group. In the subse- 

 quent pages each will be taken up separately, and the story of its 

 importation and progress in America will be told. The species are as 

 follows : 



Monodontomerus sereus Walk. Adult females hibernate within 

 the nests, but do not attack the caterpillars. 



Pteromalus egregius Forst. Females enter the nest in the fall 

 and oviposit upon the caterpillars after they have become dormant. 

 Their eggs are deposited, and the larvse feed externally (fig. 59), be- 

 coming full fed before cold weather puts a stop to their activity. 

 Transformations are completed in the spring, and adults of the new 

 generation leave the nests about two or three weeks following resump- 

 tion of activity on the 

 part of the caterpillars. 



Apanteles lacteicolor 

 Vier. Attack is presum- 

 ably made upon the very 

 small active caterpillars 

 in the fall before they 

 enter the nests for the 

 winter. The parasitized 

 caterpillars hibernate 

 and resume activity- in 

 the spring. About the 

 time when, had they re- 

 mained healthy, they 

 would have molted for 

 the first time, they die, 

 and the parasite larva soon issues and spins a white cocoon within 

 the molting web, which may or may not be upon the winter nests. 

 There is no second generation upon the caterpillars of the brown- 

 tail moth the same season. 



Meteorus versicolor Wesm. Habits essentially the same as those 

 of Apanteles until after the caterpillars have resumed activity in the 

 spring. The parasitized individuals usually live to molt once, and 

 are overcome and destroyed away from the molting web or nests. 

 The cocoons, which are characteristic of the genus, swing from the 

 end of long threads. The adults issuing from them immediately 

 attack the larger caterpillars of the brown-tail moth for a second 

 generation. 



Zygoboihria nidicola Towns. Hibernating habits similar to those 

 of Apanteles and Meteorus. The affected caterpillars become full 

 grown and spin for pupation before being overcome by their parasite. 

 Sometimes they pupate. The parasite adult issues at about the time 

 when the moth would have issued had the caterpillar completed its 

 transformations. There is but one generation annually, and no alter- 

 nate host is necessary. 



Fig. 59.— Larvse of Pteromalus egregius feeding on hibernating 

 caterpillars of the brown-tail moth. Much enlarged. (Origi- 

 nal.) 



