26 



THE SPRING GRAIN-APHIS OR U GREEN BUG.'* 



in some oats fields were parasitized. The junior author spent some 

 time in northern Texas during November and December, 1904, 



Diagram IV. — Map of the United States east of the Rocky Mountains, showing normal temperature, 

 upper line, and departure therefrom, lower line ( + , above normal, and — , below), for the critical period 

 December, 1902, to May, 1903; above normal (+) in winter and below normal (— ) in spring being 

 favorable for outbreak of spring gram-aphis. (Original.) 



investigating insects in the fields of wheat and oats without finding 

 the pest. He was not looking for this species particularly, and it 

 was doubtless still present in very Hmited numbers. 



