June 8, produced 7 young. 



June 18, produced i young. 



'l"he female continued to live a few days longer but died 

 without further issue, she having produced 59 young in 19 days. 



The results of the rearing of this species show that, as with 

 the others, the winged female is the least prolific. It is also 

 probable that some individuals are more productive of young than 

 others, and that the species as a whole may be more prolific early 

 in the season than later on towards midsummer. 



As a comparison of the rapidity with which the species 

 multiplies I append the following record of similar experiments 

 with the grain aphis, Siphoiiophora aveiue : 



A female was isolated on a wheat plant May 5, and on the 

 next day, having in the meantime given birth to four young, she 

 was destroyed. On the 14th two of these were also destroyed, the 

 remainder reaching maturity, one being winged and the other 

 apterous. These were both kept on plants under glass, and care- 

 fully watched, with the following results, the young being destroyed 

 as fast as produced: 



May 15, winged female had produced i and wingless 6 young. 



16 



17 

 18 



19 

 20 

 21 



24 



25 

 26 



27 

 28 



29 



