298 



A.V ECONOMIC ENTOMOLOGY. 



and sometimes three or more broods in the course of the year, 

 and in favorable seasons these become successively more numer- 

 ous, so that the fall brood proves the most troublesome. These 

 favorable seasons, however, do not often occur, particularly in 

 the Eastern United States, and here climatic influences or other 

 natural conditions reach the insects during the winter, so that in 

 the spring following only a normal number survive. Cultivating 

 land in crops which admit of fall ploughing is best adapted to 



Fig. 335. j^iG. 336. 



The fall army-worm.— 5, its Laphygma frugiperda and its 



head ; c, d, its body segments variations, 

 enlarged. 



avoid injury, and a frequent rotation will prevent them from be- 

 coming numerous enough to be destructive at any time. The 

 arsenites can be employed, of course, for the protection of crops 

 that admit of being sprayed. Wheat-flelds badly infested in fall 

 are not necessarily ruined or even much injured, because wheat 

 will stand cutting down almost to the ground during the latter 

 part of the season, and will yet come up vigorous and in good 

 condition the spring following. The moth that produces this 

 caterpillar is a modest, gray creature, expanding hardly more 

 than an inch, and the hind wings are pure white and semi-trans- 

 parent. It is a variable species, and ranges from an almost uni- 

 form gray to forms in which there is a considerable admixture of 

 bluish white, the ordinary lines and spots of the owlet-moths 

 being also well marked. 



