164 



INSECTS INJURIOUS TO STAPLE CROPS. 



during July, depositing tliem on tbo ripe heads if the 

 harvest be a little delayed, but on the wheat in stacli if 

 harvest is prompt. Usually the caterpillars hatching from 

 these eggs become full-grown and remain in the grain over 

 winter, but in warm seasons, esj^ecially if warm in Sep- 

 tember, and when the pest is unusually abundant, a third 

 brood of moths appear early in September. These lay 

 another batch of eggs about the middle of September, 

 depositing them upon the open ends of grain in stack or 



Fig. M.—Sitotrogi rerexlelln. a, eggs; b, larva at work; c, larva, 

 side view; d, pupa, e, moth:/, same, side view. (After Chit- 

 tenden, U. S. Dept. Agr. ) 



mow, which thus becomes more infested than that in the 

 centre. In grain stacked outside, the caterpillars of this 

 brood become fnll-grown slowly and remain in the grain 

 over winter, but if in the mow they grow faster and a 

 fourth brood of moths appear about the middle of 

 October, the moths being noticed in threshing. The 

 insects continue to breed within doors all winter as long 

 as any grain remains, though they become sluggish and 

 cease feeding during a very cold spell. The number of 



