990 
Journal of Agricultural Research 
Vol. V, No. 21 
beside females, even in contact with them, they have shown no signs of 
recognition. Sometimes they would remain by the female and com¬ 
mence feeding. Usually they would immediately wander away. Never¬ 
theless, the male appears to be constantly searching for the female. 
Although it feeds considerably at periods, it is usually engaged in running 
rapidly about over the plant. The writers have seen such a male pass 
close to a female, which has produced one or more sterile eggs, several 
times and not pay the slightest attention to her. Some time later such 
a female would produce fertile eggs, proving conclusively that he finally 
found her. It may be that the female is only in condition to mate at 
certain times and that when not in condition she offers no attraction to 
the male. 
The writers have never witnessed the entire act of copulation. A 
pair may remain in copula for at least 25 minutes, but whether or not 
the period is usually much longer than that is uncertain. During mating 
the female may move about carrying the male with her. She usually 
remains quiescent, however, with her beak inserted in the leaf or twig 
on which she rests. 
Whether or not plural mating is necessary for fertilization of all the 
eggs is a point concerning which the writers are uncertain. It is 
indicated, however, by the fact that in a few cases females have laid 
fertile eggs and later sterile ones. Certainly plural mating takes place 
quite frequently. In one case under observation a female mated three 
times before laying any eggs, the first egg being produced between three 
and four days after the last mating observed. This is very difficult to 
explain unless the suggestion that the female mates only when in the 
proper condition is incorrect, in which case it is possible that the eggs 
were not fertilized by the first two matings. The writers have never 
observed females in copula after they have laid fertile eggs, but aphides 
which have laid sterile eggs frequently mate and produce fertile ones 
later. 
OVIPOSITION 
The shortest time observed by the writers to elapse between mating 
and egg deposition is 2 days. However, in one experiment a female 
deposited a sterile egg on one day and a fertile one on the next. This 
would suggest very strongly that oviposition may take place within 24 
hours after mating. 
In the experiments the number of eggs laid by females ranged from 
1 to 6. The normal number appears to be 6, though the average was 
4.75. The rate of deposition is very irregular. In one case a female 
laid 2 in 24 hours and a third in the next 48 hours. In another case a 
female produced 3 eggs which were laid 6 and 5 days apart. In several 
cases females which had been observed in copula produced no eggs 
whatever, although living several days afterwards. On the other hand, 
