102 Annals Entomological Society of America [Vol. IX, 



oviposition to emergence required from eighteen to twenty days 

 at this season of the year. Developmental processes slow up 

 with the approach of cold weather. We do not know the num- 

 ber of generations per year, but beginning July 24th, we ran one 

 cage in which three generations matured by October 19th, the 

 first beginning to appear August 20th, the second September 

 14th and the third on the date mentioned. Assuming that the 

 parent generation required twenty days, there could be four 

 generations from July 4th up to the last of October. Under 

 field conditions at the points where the original specimens were 

 collected, this last generation might not be produced. 



In any event, there is time enough in one season for an enor- 

 mous multiplication of this parasite. Puparia collected shortly 

 before emergence of the host would probably show a much 

 higher percentage of parasitism than that shown by our figures. 

 Consequently, Paraphelinus speciosissimus may prove in the 

 future to be an important agent in the control of a serious out- 

 break of the Hessian Fly and the fact that one host may serve 

 to develop as many as ten adults would indicate that it could 

 maintain its numbers at a relatively high level during seasons 

 when the host is scarce. 



