254 



JOURNAL OF ECONO^IIC ENTOMOLOGY 



\yo\. 8 



Time of Emergence. — Considerable data was collected on the time 

 of emergence of the adult parasite. During the life history study all 

 material was examined at 8.00 a. m. and 5.00 p. m. each day for the 

 emergence of parasites. In this way it was found that the optimum 

 time for emergence was between 5.00 p. m. and 8.00 a. m. Of the 

 4,474 parasites bred during the season, 4,136 parasites, or 92 per cent, 

 emerged during the night, while 342, or 8 per cent, emerged during 

 the day. In order to determine the exact time of emergence 309 par- 

 asitized eggs were kept under hourly observation from July 31 to 

 August 12. Two hundred and seventy-six, or 88 per cent of these 

 parasites, emerged between the hours of 6.00 a. m. and 9.00 a. m., the 

 maximum emergence occurring between 6.00 and 7.00. 



Period of Emergence. — The emergence from parasite eggs laid 

 on the same day may extend over a period of from three to fifteen 

 days. During the summer months this period varied from three to 

 six days, the maximum emergence occurring the second or third day. 

 In the fall this period w^as prolonged to from eleven to fifteen days. 



Relation and Economy of Sexes. — In a number of experiments 

 conducted to determine the relation and economy of sexes, it was found 

 that one male could fertilize as many as ten females and that one fe- 

 male could mate with as many as six males. It was also found that 

 when oviposition occurred without mating all of the offspring were 

 males. When mating occurred about 70 per cent of the offspring 

 were females. The factor that influenced the number of eggs parasi- 

 tized per female was the number of eggs supplied. This factor also 

 influenced the mortality of the parasites in the host egg. When few 

 eggs were supplied double parasitism often resulted. 



Method of Oviposition. — Oviposition was observed many times 

 under laboratory conditions and in practically every case the process 

 was the same. The female parasite, on finding an egg, hurriedly makes 

 a preliminary survey of it by crawling over the egg and feeling it wdth 

 her antennae. Generally, the female in making this examination goes 

 over the entire egg, the progress being along the long axis. If the 

 egg does not suit she may discard it after this examination. If the 

 preliminary survey proves satisfactory, a more careful survey is made 

 in which the female goes over the egg slowly and examines every part 

 of it carefully by tapping with the antennae. If this examination 

 proves all right the female crawls off the egg and with her back to it 

 endeavors to find a suitable place for the insertion of the ovipositor. 

 The latter is protruded until it touches the egg and then the female 

 begins a survey by sounding various parts of the egg with the tip of 

 the ovipositor. Often it is necessary for her to change position once 

 or twice before a suitable place for its insertion is found. When a 



