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. 
-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.) 
