322 Journal of Agricultural Research voi. xviii, no. 6 



MIGRATION 



The males leave the summer host soon after becoming mature and 

 fly to the apple trees. The earlier males usually arrive before the ovipara 

 are mature. In such cases they usually wander about on the trees some- 

 what and then frequently settle down on the leaves for short periods at 



least and feed. 



SEXES 



MATING 



As soon as the ovipara become adults they usually wander from the 

 leaves to the twigs. The males also leave the foliage; and nearly all 

 the mating occurs Upon the twigs, although occasionally couples in copula 

 can be found upon the leaves. 



The males do not appear to have any special means for locating the 

 ovipara. They wander restlessly about, and if they meet a female 

 immediately try to mate with her. Sometimes the female will remain 

 quiet for a few moments and at others the male is obliged to climb on 

 her back while she is walking. Frequently a female will wander about 

 with the male on her back throughout the entire process, which usually 

 lasts from lo to 15 minutes or even a little longer. 



As soon as the male leaves the female the latter recommences wander- 

 ing, in case she had stopped, till she finally locates a position for oviposi- 

 tion which suits her. The male in the meantime immediately starts 

 searching for another female. A female also may mate at least twice 

 before laying any eggs, though one mating seems to be sufficient for fer- 

 tilization. It seems to be due simply to the fact that even if she has 

 mated she makes no attempt to get away from any other male which 

 she may meet, and consequently mating occurs again. Males, so far as 

 our observations go, are always present in smaller numbers than are the 

 females. 



REPRODUCTION 



Having selected a place for oviposition the female usually settles down 

 and feeds for some time, occasionally even for several hours, before 

 laying her first egg. Sometimes after laying this she remains in about 

 the same position for a time and then deposits another. Usually, how- 

 ever, the insect will wander about considerably between the acts of 

 oviposition, selecting a different location for each egg. A second female, 

 however, may deposit an egg beside that already laid by the first aphid. 

 In fact, in particularly favorable positions about buds, in injuries to the 

 bark, etc., several eggs may be found and often several females may be 

 seen packed closely together, all ovipositing at the same time. Occasion- 

 ally the ovipara will wander back to the leaves and feed for short periods, 

 soon returning to the twigs to continue oviposition. 



