ENGLISH GRAIN LOUSE 187 



wheat or other small grain, as well as grass growing around the 

 edges of the fields, should be destroyed. Varieties of wheat with 

 coarse, strong stems are less liable to injury. Field wheat should 

 be sown as late as possible. Burning the stubble where practicable 

 will destroy the flaxseeds. A good system of plowing, crop rota- 

 tion, and modern methods of agriculture, however, are the best 

 methods of prevention. 



The Wheat Stem Maggot (Meromyza americana Fitch). Un- 

 like the Hessian fly, the larva of this two-winged insect feeds imide 

 the stem, causing it to become discolored or to die. Sometimes 

 the stem is cut off entirely. The adult fly is one-fifth of an inch 

 long, of a general yellowish-white color, with three black stripes 

 on the thorax and abdomen. The eyes are bright green. The 

 larva or maggot is light green in color, one-fourth of an inch long, 

 tapering toward either end. The adults lay eggs at intervals 

 during the summer. The winter is passed by the larvae in young 

 plants, where they transform into pupae. This insect also attacks 

 rye (Fig. 206). 



Control Measures. Since this bisect feeds and breeds also in 

 wild grasses, it is difficult to control. Where possible and safe, it is 

 suggested that the stubble be burned over. Fall-plowing, clean 

 cultivating, and rotation of crops are the most desirable 

 measures of prevention. 



The English Grain Louse. Only in latitudes where the winters 

 are comparatively mild will grain plant lice (Macrosiphum granaria 

 Buckton) seriously injure crops. They are found on wheat, rye, 

 and other winter grains. They feed on the leaves when young and 

 later gather on the ripening kernels in the heads, injuring the 

 yield and quality of the grain very seriously. 



The life history is approximately the same as for other plant 

 lice. There are both winged and wingless forms. Each female 

 gives birth during the summer to forty or fifty young, the same 

 reaching maturity in about twelve days. When there is need of 

 migration, winged forms appear. As many as fourteen generations 

 have been observed in one summer hi the latitude of Minnesota. 

 These lice are yellowish green. The two honey tubes projecting 

 from the back of each insect are quite long and black hi color. 



Control. Parasites and other natural enemies generally hold 

 this pest in check. No practical remedy is known and none 

 needed in most latitudes. Clean farming and rotation of crops 

 are recommended. 



