Any 
Contributien from the Bureau of Entomology 
L. O. HOWARD, Chief 
Washington, D. C. PROFESSIONAL PAPER June 24, 1919 
THE GRAIN BUG.’ 
By D. J. CAFFREY and GEO. W. BARBER, 
Scientific Assistants, Cereal and Forage Insect Investigations. 
A CONTENTS. 
Page Page 
MP OUUGHON Reser see inact hoe ee Le pelabitsoimymphse. seep tae eee eee ae 18 
ELISLORY Meme ee mae Me aa Se of Zuo HELA bitsOnadUlessaaceiec seeps cece creer sade 20 
DISERIDUTIOMM seer ee i tose aes Poe eS Ore Naitunalrenem ester cee este eee ee ee 28 
Food plants. ......-- JS EUS race Eee ee 4y\AControlmethodss. 202s - seats ses eeeee eee see 32 
Characteroteimi Unymere eels cei one oe 4 | Associated species of plant bugs.....-------- 33 
IDESCMP MOMEMa seer ner. ohe soc oe feo sc an ec le8 Gla Summary sess) SeN Fa Sek eee. sehen et 33 
Life history and development.........-.-.-.- 1Opipeleiterature;citedicn jo. - och aries nme eee 34 
Deasonal developments. ce.2ccse-2-- 5-5 5-5- + 16 
INTRODUCTION. 
During the past few years the grain bug, (Pentatoma) Chlorochroa 
say Stal, has become a pest of considerable importance to the farm- 
ers of the intermountain and southwestern States. It is now re- 
garded as a serious menace to the growing of wheat and other small 
grains in both the irrigated and nonirrigated districts within the 
area of its distribution. 
The vital damage is caused by the piercing of the newly formed 
heads of cereals and the feeding on the liquid contents, by which the 
formation of the grain is prevented or its weight greatly reduced. 
The recent development of C. sayz as an economic pest is due to 
an artificial change in its environment and food plants. This condi- 
tion has been brought about by the cultivation of large areas formerly 
devoted to grazing, which practically eliminated many of the native 
food plants and caused the insect to attack some of the crops grown in 
its former habitat. The change to more succulent food plants, to- 
gether with the better facilities for hibernation in the cultivated 
areas, resulted in a marked increase of the pest. 
1The observations detailed in this bulletin were made by the senior author in 1915 
and by the junior author in 1916 during a destructive outbreak of the species in north- 
eastern New Mexico and adjacent territory. The experiments were carried on at the 
Field Laboratory of the Bureau of Entomology located at Maxwell, N. Mex. 
Mr. E. H. Gibson, of the Bureau of Entomology, kindly redescribed the adult of the 
species and assisted in the preparation of notes on the history, synonymy, distribution, 
food plants, and bibliography. 
103881°—19-—— 1 
