BIOLOGICAL STUDIES ON THKEE APHIDID^. 



147 



I have "worked out in the insectary (1906) the summer history as 

 regards the number of generations, rate of multiplication, number 

 of young, etc. Aphis maiclis was collected by Mr. Kelly June 26, 

 and specimens sent in by him were reared on sorghum and broom 

 corn. From that date until killed by the cold weather in the fall a 

 maximum of 17 generations was obtained. (See Table VII anil 

 fig. 33.) 



Fig. 33. — Periods and succession of generations in Aphis maidis, 1906. 

 Table VII. — Line of generations of Aphis maidis, June 26-NovemI)er 22, 1906. 



a Collected on l)room corn. 



b Became adult November 22, but disappeared before giving birth to any young. 



