174 



FESTS OF GARDEN AND FIELD CROPS 



small dark dots. There is a rather dark stripe down each side of 



the body. 



Frequently this species is abundant without developing the instinct 



of marching in " armies." It feeds on alfalfa, sugar beets, and many 



other field and garden crops. Winter 

 is passed as pupa in the ground. 

 There are two broods in the North; 

 four in the South. 



Control depends on the nature and 

 extent of the crop attacked. In 

 limited areas apply arsenicals. In 

 large fields the worms may be killed 

 by crushing them with a heavy roller. 



Fall plowing and disking, combined with cultivation where feasible, 



will kill many of the overwintering forms. 



Fig. 199. — Adult of the Fall 

 Army Worm. Original. 



The Beet Army Worm (Laphygma exigua Hbn.) 



In some of the Western states this species has periods of disastrous 

 abundance on sugar beets. Its invasions occur at the same time as 

 those of the fall army 

 worm. The larva 

 resembles the latter, 

 but lacks the distinct 

 black dots. On each 

 side there is a dark 

 stripe, along the 

 lower edge of which 

 is a series of white 

 dots. The winter is 

 passed as an adult 

 moth. There are 

 two broods in the summer, and apparently the normal food plants 

 are certain weeds. Clean culture is indicated, in order to keep down 

 the weeds on which the species may live in spring or fall. The 

 worms may be poisoned by applying Paris green or arsenate of lead. 



Fig. 200. —Adult of the Beet Army Worm. 

 Slightly enlarged. Original. 



