EARLIEST OBSERVATIONS IN AMERICA. 



15 



On June 7, 1884, Mr. Albert Koebele found this species infesting 

 wheat plants at Cabin John Bridge, situated in Maryland a few miles 

 above Washington, and about July 1 of the same year the senior 



Diagram I. — Maps 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, 1881, to May, 1882; above normal (+) in winter and below normal (— ) in spring being 

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



author found it in one of his rearing cages, placed out of doors at 

 Oxford, Ind. (see fig. 2). In the latter instance the species showed 

 a preference for wheat plants over those of rye, and in September it 



