FARMERS' BULLETIN 835. 



the leaves of wheat. These eggs hatch into little maggots which 

 crawl down into the leaf sheaths. There they live upon the plant's 

 sap, which they obtain by gnawing into the soft portions of the 

 stem. Usually two, but sometimes three or more, generations of the 

 insect occur during a year. 



One main generation of flies (see fig. 2) appears in the fall, the 

 large proportion of the maggots becoming full-grown before the 

 severe weather of winter arrives, when they change into brown seed- 

 like forms known as " flaxseeds." These may be found within the 

 leaf sheaths in young wheat plants, usually at or beneath the surface 

 of the soil. These overwintering "flaxseeds" produce the spring 

 generation of flies. These, in turn, lay eggs from which hatch mag- 



gots that cause great 

 injury to wheat, no- 

 ticed about harvest 

 time, when the straws 

 break off and the crop 

 is said to be "straw 

 fallen." 



After the Hessian 

 fly has once thor- 

 oughly infested the 

 crop of wheat there is 

 no known means of 

 saving it, and the 

 only known means of 

 preventing damage 

 from the fly is to keep 

 it out of the wheat. 

 For this reason the 



young 



, 



wheat should 



FIG. 1. The Hessian fly (Phytophaga destructor) : Adult 

 female. Much enlarged. 



oughly in order that 



the presence of the brown " flaxseeds " may be detected late in winter 

 or very early in the spring, and if these are found to be present in 

 large numbers it will pay to plow down the wheat at once and pre- 

 pare to plant corn, oats, or some other crop in its place. In this 

 way the fertilizing value of the green crop will be retained in the 

 soil and it will still be possible to secure a crop of grain or vegetables 

 from the field during the current year. 



The remedies for the Hessian fly are entirely preventive and are as 

 follows : 



(1) Immediately after harvest, or as soon thereafter as practicable, 

 plow the wheat stubble down deeply, at least 5 inches deep if possible, 

 in order to destroy the maggots and " flaxseeds " which may re- 

 main in it. This is for the protection of future crops. 



