460 JOURNAL OP ECONOMIC ENTOMOLOGY [Vol. 2 



Conclusions 



It was hoped to supplement the winter work on the cocoons of these 

 moths with a study of the parasites which attack the immature cater- 

 pillars and eggs during the summer, but it was found to be wholly 

 impracticable. Egg parasites are known to exist, and probably those 

 which will attack one species will breed with equal freedom in all. In 

 several instances the eggs of promethea, which are somewhat easier to 

 find than those of the others, owing to their being deposited in some 

 numbers together, have been found with exit holes of some parasite. 

 It is quite possible that parasitism of the eggs is at times a considerable 

 factor in the control of the host. 



The parasites of the young caterpillars are hardly better known. 

 There is one which is related to Apanteles which issues from the first 

 and second stage caterpillars of luna and polyphemus and possibly 

 attacks the others also, but the cocoons have usually been hatched, or 

 have been attacked by secondaries when discovered. It appears to be 

 rather abundant. A Limnerium attacks the caterpillars of promethea 

 before they are half grown and may attack the others also, but no 

 attempt has been made to collect and rear it. 



Altogether it would appear from the very limited observations 

 which have been made, that the parasites of the immature caterpillars 

 outrank in importance those which attack the larger caterpillars and 

 pupae, but until more is known concerning them, and the part which 

 they play in the control of their common or respective hosts, it is 

 impossible to draw any conclusions as to their relative effectiveness. 



The percentage of parasitism indicated by the study of the cocoons 

 was greater than was expected, and it is believed that the extraordi- 

 nary variation in the percentage thus destroyed in different localities 

 is indicative of the importance of this group of parasites as a factor 

 in natural control. 



