132 



PESTS OF GARDEN AND FIELD CROPS 



grains here and there in a green, growing field. Often the stem below 

 the head will be somewhat shriveled or discolored. A tiny maggot may 

 be found within the stem. The adult is a small fly with a striped body. 



The first generation of 

 flies emerge in early sum- 

 mer from the 3"oung plants. 

 Their offspring are the brood 

 of maggots that cause the 

 blanched heads. 



The adults of these mag- 

 gots emerge after normal 

 threshing time, and there 

 follows a midsummer gen- 

 eration on volunteer grain 

 or wild grasses. Adults 

 from these lay eggs on fall 

 wheat or native grasses, and 

 the maggots from these sur- 

 \ive the winter, completing 

 growth in the spring. On 

 fall wheat they injure the 

 base of the plant. 



Prompt threshing and 

 stacking will kill many of 

 the insects in the ripe straw, 

 and bury the survivors in 

 the stack where the flies can- 

 not get out to go through 

 Late sowing of fall wheat 



Fig. 113.- 

 enlarged, 



-The Wheat-stem Maggot. Adult, 

 and work, natural size. Original. 



the midsummer generation on grasses, 

 probably will help to some extent. 



The Stalk Borer {Papaipema nitela Guen.) 



The stalks of many kinds of plants, such as tomato, corn, oats, 

 barley, and others, are attacked by a worm which bores into them 

 from without, feeds within, and frequently bores out again, moving 



