50 



THE SPRING GRAIN-APHIS OR 



" GREEN BUG." 



zero, with no protection, is fatal to Toxoptera, except to the egg, but 

 the fact that it withstood the winter in 1890 can easily be accounted 

 for. That winter was unusually mild throughout, with the excep- 

 tion of the dates mentioned, and if one consults the weather records it 



Fig. 9.— The spring grain-aphis: Oviparous female, showing eggs within the abdomen. 



actual size, 2.25 mm. (Original.) 



Enlarged; 



will be found that on January 24 there were 3.5 inches of snow, Feb- 

 ruary 9, 3.4 inches, and March 6, 4 inches. The covering of snow in 

 each instance would appear to have been sufficient to protect the 

 Toxoptera, as on December 8, 9, and 10, 1909, at Lafayette, Ind., 

 the temperature fell as low as from — 1° F. to —4° F. below zero, and 



plant-lice of all kinds, in 

 ^ the rearing cages out of 



doors, were killed, while 

 those in a near-by wheat 

 field, covered with several 

 inches of snow, were found 

 to be in good condition on December 13, at which time the cold 

 spell was broken and the ground began to thaw. 



As a rule, Toxoptera breeds slowly in October and November, at 

 which time the majority become oviparous females (figs. 9, 10) and 

 males (fig. 6). 



Fig. 10.— The spring grain-aphis: Hind tibia of oviparous 

 female. Greatly enlarged. (Original.) 



