SMITHSONIAN INSTITUTION LIBRARIES 



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mented by burning all screenings of the wheat if thrashing precedes 

 the fall appearance of the fly. 



Plowing under stuhhle. — In line with burning, and of nearly equal 

 importance, is turning the stubble under bj^ deep plowing, and after- 

 wards rolling the field to compact the earth and prevent any flies which 

 may mature from issuing. 



Rotation of crops. — The regular practice of a sj^stem of rotation in 

 the growth of crops is of the utmost importance in avoiding fly dam- 

 age. Its value may be offset at times by invasion from neighboring 

 fields of wheat on other farms, but usually comparative freedom from 

 attack will result and the benefit will extend to the other crops coming 

 in the system adopted in checking the insect enemies of these at the 

 same time. 



Trap or decoy plantings. — One of the earliest preventives recom- 

 mended and one of considerable value is the early planting of narrow 

 strips of wheat to act as decoys to attract the flies wdth the object of 

 turning the infested wheat deeply under wdth the plow in late fall. 

 This procedure will greatly reduce the numbers of the pest and should 

 give nearly complete immunity to late-planted wheat. 



Destruction of volunteer wheat. — The supplemental fall brood ante- 

 dating the principal brood may be prevented if all volunteer w'heat be 

 plowed under or destroyed within a few weeks after its appearance. 

 This is of especial value in the North, where spring wheat is grown, 

 and where the brood developed on the volunteer wheat may be the 

 principal means of carrying the insect through the winter. 



Growth of resistant tvh'eats. — As indicated in the paragraph, "Effect 

 on Wheat," the importance of selecting varieties wdiich are less injured 

 by the attacks of the fly, will be at once apparent. Such wheats are 

 those having coarse, strong stems, and varieties which "tiller" freely 

 or develop numerous secondary shoots. Among such wheats are the 

 Underbill, Mediterranean, Red Cap, Red May, Clawson, etc. 



C. L. Marlatt, 

 First Assistant Entomologist. 

 Approved : 



James Wilson, 



l:iecretary. 



WASHINC4T0N, D. C, April 13, woo. 



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