April, '14] MCCOLLOCH: CHINCH BUG PARASITE 223 



of 3.7 eggs; thirty-one females of the third generation parasitized an 

 average of 3.7 eggs. The largest number of eggs parasitized by a 

 single female was 13. 



Twenty-nine females, that had not been allowed to oviposit, were 

 dissected and the number of eggs in the ovaries counted. The smallest 

 number of eggs found was 13, and the largest 29, while the average 

 was 22.8. 



Proportion of Sexes — The number of females greatly exceeds 

 the number of males both in the field and in the laboratory. Of fifty- 

 one parasites collected in the field, forty-seven were females, and of the 

 786 parasites bred out in the laboratory, 512 were females. The 

 number of females bred out in the laboratory is low because of several 

 cases of parthenogenesis in which case the parasites obtained were all 

 males. On an average about 70 to 75 per cent of the parasites ob- 

 tained in the laboratory were females. 



Parthenogenesis — This insect can breed parthenogenetically, but 

 the number of eggs parasitized per female was usually low, and many 

 of the offspring failed to develop. Fifteen trials were made with 

 unfertihzed females, and in four cases no oviposition was noticed. 

 Of the 120 eggs parasitized by unfertilized females 50 failed to reach 

 maturity. Sevent}^ parasites were bred out and 66 of them were 

 males. 



Habits in the Field — The short existence of the adult is occupied 

 in constant activity during the day in hunting for mates, and ovipos- 

 iting. Feeding, if any, requires a very short time, and the main part 

 of the insect's life is directed towards reproduction. In the wheat 

 fields the parasites were always moving about on the plants near and 

 below the surface of the ground. Unless disturbed, the adults sel- 

 dom take to the wing. Generally only one parasite was found at a 

 time, but occasionally two or more were found in a very small area. 

 Although it seems probable that they spend their lives in comparatively 

 limited areas, they also distribute themselves to a greater extent than 

 might be expected. It is probable that the ^\^nd aids greatly in this. 



Food — The parasites were never observed to feed in the field, but 

 in the laboratory they fed readily on the sweetened water supplied 

 them. 



Flight — The flight of this insect is by short jerky flights. Just 

 how far they may fly at one time has not been determined. They 

 have been observed to fly from a leaf of corn five feet from the ground, 

 but from here the flight could not be followed. In the laboratory the 

 flights were generally short, covering only a foot or two. 



Effect of Oviposition in Different Stages of the Egg — The 

 parasites seem to prefer those eggs in which the chinch bug embryo 



