INSECT PEST SURVEY BULLETIN 
Vol. 15 Supplement No. 6 
HESSIAN FLY INFESTATION AT HARVEST TIME 1935 
C. M. Packard, Senior Entomologist 
Division of Cereal and Forage Insect Investigations 
Bureau of Entomology and Plant Quarantine 
U. S. Department of Agriculture 
and the 
State Agricultural Experiment Stations of Missouri, Illinois, and Ohio 
The surveys here reported cover the main winter-wheat regions of 
the central and eastern parts of the United States. The hessian fly has 
increased greatly in abundance since last year throughout much of the 
Wheat Belt, as a result of favorable weather conditions "both In the fall 
and in the spring. Late summer rains last year in the East Central 
States, caused the growth of much volunteer wheat, which served as a me- 
dium for the development of an extra, late-summer generation of fly and 
an important source of severe spring infestations in wheat sown this year. 
The situation was further aggravated by considerable wheat sown early 
last fall, which also became infested by the fall "brood and provided an 
additional source of spring infestation. During the past year the ra- 
pidity with which this insect can increase in two successive favorable 
seasons has "been strikingly manifested. 
On August 22, 1?35> conditions were still favorable for further 
increase, Parasitization and summer mortality of puparia in stubble 
have '"oeen moderate. Volunteer wheat is already growing, and pupation 
and egg laying have begun. With continued favorable conditions this com- 
ing fall, a severe outbreak seems certain, and strict observance of the 
safe sowing dates is especially important. Wheat stubble and volunteer 
should also be promptly plowed under wherever possible. 
Hessian fly is present in threatening numbers throughout a belt 
of variable width, shown on the following map, extending from southeast- 
ern Kansas to east-central Pennsylvania, and including the southern two- 
thirds of Missouri, central Illinois, and most of Indiana and Ohio, with 
the area of greatest intensity centering in Indiana, where extremely se- 
vere infestations occurred in some fields. The Shenandoah Valley of Vir- 
ginia also contains considerable infestations. Most of the data from 
Ohio and Illinois, and part of the Missouri data, were obtained by State 
entomologists. In the other places the data were obtained by Bureau en- 
tomologists and were based on individual field samples consisting of 
fifty stems each. The data serving as the basis o-2 this report are sum- 
marized in the following table: 
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