9 



still enable the observer to detect the infestation. Of course later on 

 the infested plants chano-e to 3'ellow and then brown, but the darker 

 color and rank growth of leaf always precede this. 



In summer, in both springy and fall wheat, the effect of the fly is to 



Fig. 10. — Young wlieut plant infesteii liy tlu' lU'ssian fly (oris^^inal). 



cause the straw to break over before harvest. It is then said to be 

 "straw fallen.'"' 



IMMUNE OR DISTASTEFUL VARIETIES OF WHEATS. 



There is no such thing* as "flv-proof wheat." Most wheats will suf- 

 fer when the plants are young, regardless of variety. In experimen- 

 tal sowings a variety that seems to escape attack one \'ear may suffer 



