THE SPRING GRAIN-APHIS OR "GREEN BUG." 
INTRODUCTION. 
Investigations of the spring grain-aphis, or "green bug" (Toxop- 
tera graminum Rond.) (fig. 1), in America were first begun by the 
senior author in the year 1884, at Oxford, Ind., where the insect was 
accidentally introduced with, or had in some obscure way gained 
access to wheat plants which had been transplanted from the open 
to rearing cages standing out of doors on a blue-grass lawn (June 6) 
and used in carrying out investigations on the greater wheat straw- 
worm (Isosoma grande Riley). At that time the insect gave no indi- 
cation of its present economic importance and for this reason was not 
then given special attention. 
In 1890, when the pest really first gave evidence of its capabilities 
as a grain destroyer over a wide range of country, the senior author 
again took up its study, gaining considerable additional knowledge 
of its habits and of the influences of temperature and season upon 
its abundance. (See Diagrams I-V.) 
The less serious outbreak of 1901 was not investigated and our 
information relative to it is derived chiefly from correspondence of 
the bureau for that year. 
The incipient outbreak of 1903 was reported from Texas by Prof. 
E. D. Sanderson, at that time State entomologist, and from South 
Carolina by correspondents of the bureau. 
The last and most disastrous outbreak of all, that of 1907, was 
investigated not only by both of the authors, but by Mr. C. N. 
Ainslie, who began his work on the species at Summers, Ark., on 
March 18, continuing the investigation almost uninterruptedly 
through the summer, working over the country from central Okla- 
homa northward to Canada, and returning to Washington in Sep- 
tember. The junior author spent April, May, and a portion of 
June in Oklahoma and Kansas in field investigations, returning to 
Richmond, Ind., where he was at that time located and where he 
took up a systematic study of the insect, its habits, and develop- 
ment — a study which has been continued up to the time of prepara- 
tion of this manuscript for publication. Messrs. E. O. G. Kelly and 
T. D. Urbahns spent much time in a study of the parasites; indeed/ 
most of the assistants in cereal and forage insect investigations have 
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