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JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 7 



had not yet begun to show the reddish color. In several experiments 

 in which parasites were introduced to red eggs, there was only one 

 case where the parasite developed and destroyed the embryo. Of the 

 eggs collected in the field, only four red eggs were found that later 

 gave up parasites. 



Host Relations — In all of the experiments, the chinch bug egg 

 was the only one in which j;his parasite would oviposit. A number of 

 experiments were conducted in which parasites were given eggs of 

 false chinch bugs, and other hemipterous eggs, but no parasitism oc- 

 curred. 



Length of Adult Life — Owing to the fact that the adults were 

 kept in small vials and without food, there is httle doubt but that 

 the length of life was greatly shortened. The length of life varies 

 greatly, ranging from a few hours to twenty-five days. Temperature 

 has much to do with the length of the adult life. During the spring 

 the adults live on an average of about 93 hours. From June 9th to 

 September 1st the average was from 40 to 60 hours, and after Sep- 

 tember 1st the average was considerably over 100 hours, in some 

 cases reaching 350 hours. 



Food also plays a large part in the length of life, and the more often 

 the parasites are fed the greater the length of life. Table II shows the 

 results of feeding parasites. 



TABLE II.— SHOWING EFFECT OF FOOD ON THE LIFE OF THE FEMALE 



Length of Life Cycle 



The length of the life cycle was found to vary with the temperature. 

 The average time between the collection of chinch bug eggs and the 

 emergence of the parasites in May and June was 13.9 days for 81 

 individuals. 



The average length of the life cycle for the second generation was 

 14.3 days; for the third generation 11.9 days and for the fourth genera- 

 tion 9.9 days. Owing to the scarcity of chinch bug eggs at this time, 

 it was impossible to continue the brood study for about two weeks. 

 From the last of July to the first of September 249 parasites were bred 

 from eggs collected in the field, and the average time between collec- 



