NEW YORK STATE MUSEUM 5 1 



HESSIAN FLY 

 Phytophaga destructor Say 



The Hessian fly is usually found in small numbers in most grain 

 fields and occasionally it becomes exceedingly abundant and may 

 then destroy a large portion to nearly the entire crop over extended 

 areas. It depends more than many other species upon favorable 

 climatic conditions at the time the grain is developing and to a less 

 extent in all probability upon the relative abundance of natural 

 checks, especially parasites. Those desirous of detailed information 

 in regard to this insect are referred to the author's report for 1901, 

 State Museum Bulletin 53, pages 705-30. 



The above conditions make it very desirable to keep watch upon 

 this and associated insects. A Hessian fly survey was started in 

 19 1 7 in a small way by Prof. C. R. Crosby of Cornell University 

 and the late W. R. McConnell of the United States Bureau of 

 Entomology. The latter has been succeeded in this work by P. R. 

 Meyers of the federal Hessian fly laboratory, Carlisle, Pa. These 

 workers have kindly placed the data at our disposal. 



The information already secured has been of material benefit in 

 making possible a somewhat accurate forecast of probabilities and 

 as this information accumulates from year to year, the normal vari- 

 ations under New York State conditions can be interpreted more 

 successfully. 



The following brief tabulation summarizes conditions as they 

 existed in 191 7: 



Percentage of wheat straws infested with Hessian fly puparia, 191 7 



Erie .... 



County 



Locality 

 . . . . Clarence 



Per cent 



stubble 



infested 



4 



A 



Monroe . 





. . . . West Henrietta 



Niagara . 

 Orleans . 





West Henrietta, south 



. . . . Lockport, 8 mi. S 



Lockport, 2 mi. S 



Lockport, 3 mi. S 



. . . . Albion, north of. 



4 



2 



2 



2 



6 



Tompkins 



Carlton 



Waterport 



. . . . Ithaca Exp. Sta 



2 



8 



4 



An idea of the amount of work involved, the number of localities 

 visited and fields examined is given by the following tabulation 

 which summarizes very briefly the Hessian fly conditions for 1918. 



