Dec. IS, I9I9 Apple-Grain Aphis 323 



LOXGEVITY 



In many cases, and apparently in most, the female dies shortly after 

 depositing her last egg. The duration of the period of oviposition varies 

 greatly with different insects, however, and in some cases the females are 

 obliged to wait for some little time after becoming mature before males 

 find them and mating takes place. Consequently the total length of 

 life varies greatly with different individuals. The minimum, however, 

 is about 20 days; this is for females which deposit only two or three eggs. 

 The maximum can not be given accurately, since those ovipara which 

 lived the longest in the experiments continued on the plants till December. 

 Such insects during particularly cold weather became quiescent for several 

 days at times and frequently did not oviposit for several days at a time, 

 even during intervals of warm weather. Frequently some insects were 

 killed by cold weather while others, as old or even older, survived. The 

 life of this form, therefore, depends greatly upon whether it is bom 

 early or late, and upon the general temperature conditions prevailing 

 during the season. 



The males are about as long-lived as the females, omitting the excep- 

 tions just noted among the latter. The principal place of variation 

 among individual males is the period from migration to mating, those 

 insects which are obliged to wait for the females to mature usually 

 living somewhat longer than the others. 



OVIPOSITION 



The greatest number of eggs produced by one mother in the experi- 

 ments was seven. Others produced from one to three eggs. The custom 

 of dissecting ovipara and deriving the number of eggs from the number 

 of immature ova seems unsafe for aphids, since in several species it has 

 been proved that some such ova do not become fully developed eggs 

 but disintegrate within the bodies of the ovipara. From the observations 

 made by the writers, therefore, it can be stated only that this species 

 may lay as many as seven eggs. 



FEEDING OF OVIPARA 



As has been previously stated, the fall migrants settle upon the leaves 

 of apple trees and produce their progeny there. From the results 

 obtained in our experiments it seems that, while the stem mothers and 

 spring forms on apple prefer tender, succulent foliage from which to 

 obtain their food, the ovipara need hard, matured leaves. Most of the 

 trees used in our experiments were taken from the field about three or 

 four weeks before they were used for food. The old leaves dropped off 

 in nearly every case, causing some of the buds to develop and produce 

 small, succulent foliage such as the spring forms fed upon. In most cases 



