ANNALS 



OF 



The Entomological Society of America 



Volume 1 1 



JUNE. 1909 



Number 2 



INVESTIGATIONS OF TOXOPTERA GRAMINUM AND ITS 



PARASITES. 



By F. M. Webster, 

 bureau of entomology, washington, d. c. 



This minute insect (see figS. i, 2), aside from its economic 

 importance, which, by the way, is very great, has become the 

 basis of a long series of thorough investigations, carried out by 

 several assistants of the Bureau of Entomology, under my direc- 

 tion. My own studies of the species were made largely during 

 the years 1884 to 1890, while employed by the old Division of 

 Entomology. As the subject of this paper may not be familiar 

 to all entomologists it will be better to begin, historically at least, 

 with our first knowledge of the species in its native country, 

 if, indeed, we might with our present information, be allowed to 

 designate for it a place of nativity. 



a 



Fig. 1. — The spring grain-aphis (Toxoptera graminum) : a, Winged migrant 

 viviparous female; 6, antenna of same. a, Much enlarged; b, highly magnified. 

 (From Pergande.) 



67 



