April, '14] 



MCCOLLOCH: CHINCH BUG PARASITE 



225 



tion and emergence was 9.8 days. The average length of the hfe cycle 

 for the sixth generation was 15.2 days; for the seventh generation 17.6 

 days, and for the eighth generation 27.8 days. Table III gives the 

 brood study. 



TABLE III.— SHOWING THE AVERAGE LENGTH OF THE LIFE CYCLE 



First Appearance in Spring — Inasmuch as the first parasitized 

 chinch bug eggs were found on April 28, it is certain that the parasites 

 were out before this date. The first chinch bug eggs were found in 

 the field on April 24. 



Last Appearance in Fall — -The last parasite observed in the field 

 this fall was on October 14. A parasite was bred out from a clump 

 of crab grass that had been brought into a warm room on November 

 6, but the probability is that it was hibernating as a pupa in a chinch 

 bug egg. 



Number op Generations— The exact number of generations has 

 not been worked out, but there are about nine or ten. From May 19 

 to July 5 there was obtained four generations of adults in the life 

 history work. At this time the chinch bug eggs became very scarce, 

 as it was the interval between broods, and thus it was not possible 

 to carry on the life history again until July 23. From then on until 

 October there was obtained four more generations. The interval 

 during which the life history work was forced to be dropped was about 

 two weeks, or almost the length of the life cycle, so that it would appear 

 that there might easily be nine generations a year. 



Distribution 



This parasite was first discovered during the spring in chinch bug 

 eggs collected in a wheat field near Manhattan. During the summer 

 it was found in every grain field around Manhattan, and, in fact, 

 every place where chinch bug eggs were found. In August a hasty 

 survey of the state was made, and parasites were found in the following 

 counties: Ellis, Ford, Kiowa, Ellsworth, Kingman, McPherson, Har- 

 vey, Sumner, Cowley, Riley, Pottawatomie, Montgomery, Allen, 



