THE YELLOW CLOVER APHIS. 35 



wise varied <'onsid(M-ably, cov(Miii<j; from 4 to 32 days, with an avcraj^o 

 of 15.4 + days. Tlic lai-o;cst number of yomijj; produced by an indi- 

 vidual female was 99 and the average of tlie 22 regular generations in 

 the series was 50, averaging 3.2 + young per day per female through- 

 out the entire season, the largest number of young produced in a single 

 day by one female being 9. 



Witli only an occasional exception the aphides in these experiments 

 were wingless. Crowded conditions, predicative of a shortage of food, 

 always resulted in a large peicentage of winged forms. 



Messrs. W. J. Phillips and T. 11. Parks followed this species through 

 two series of generations in 1909 at La Fayette, Ind., beginning with 

 young found in the field May 13, and a synopsis of their experiments 

 is here given in Tables III and IV. In general the results they ob- 

 tained agree with our own studies in 1913. 



