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UNITED STATES DEPARTMENT OF AGRICULTURE 
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BULLETIN * 
Wasuineton, D. C. 640 Marcu 17, 1915. 
Contribution from the Bureau of Entomology, L. ©. Howard, Chief. 
THE HESSIAN FLY.' 
By F. M. Wesster, : 
In Charge of Cereal and Forage Insect Investigations. 
INTRODUCTION. 
Probably no other insect causes more damage to the wheat crop 
of the United States than the Hessian fly, though the chinch bug 
is doubtless a close second. During years when it is excessively 
abundant, hundreds of thousands of acres of wheat may be either 
wn 
Fia. 1.—The Hessian fly ( Muyetiola destructor): Adult female. Much enlarged. (Author’s illustration.) 
totally destroyed or so badly injured as to reduce the yield 50 to 75 
per cent, and the monetary losses expressed in dollars would run far 
up into the millions. This insect has long been known to ravage 
1 Mayctiola destructor Say; order Diptera, family Itonide. 
NotEr.—This bulletin is of interest in all the grain-growing sections of the United States, but especially 
in the regions shaded in the distribution map (fig. 8, p. 7). It is a revision of Circular No. 70 of the 
Bureau of Entomology. 
69743°—Bull. 643—15 
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