CEREAL PESTS INSECTS 485 



Fortunately certain parasitic and predaceous insects 

 are usually a good check to this insect. There is no very 

 effective remedy, but burning the straw and stubble, and 

 eradication of volunteer grain as soon as possible after 

 harvest may destroy many of these pests. 



530. The army worms. Though these caterpillars 

 probably cause some injury to cereal crops in some part 

 of the country every year, severe injury usually occurs 

 only at considerable intervals in any one district. The 

 3 principal species are the army worm proper (Hello- 

 phila unipuncta, How), the fall army worm (Laphygma 

 frugiperda, S. and A.), and the wheat-head army worm 

 (Meliana albilinea, Hbn.). 



The true army worm confines its damage particularly to the 

 region east of the Rocky Mountains. The adult is a pale or yellow- 

 ish brown moth, with a white spot on the center of each fore wing. 

 The minute white eggs are usually laid in strings beneath the sheaths 

 of grass culms, also occasionally in other situations or beneath the 

 sheaths of culms of other plants. The eggs hatch in 8 to 10 days, 

 and the young caterpillars feed for a time in the fold of the leaf, but 

 soon are able to consume entire leaves. Ordinarily the larvae feed 

 mainly at night or in damp cloudy weather, remaining hidden during 

 bright days. They reach full growth in 3 or 4 weeks, attain a length 

 of ll inches, burrow into the ground and transform into brown 

 chrysalids. In about 2 weeks the perfect moth results. Several 

 generations are produced each season 2 or 3 in the North, and 4 or 

 more in the South. It has not been definitely determined in which 

 stage this insect passes the winter in the various portions of its 

 range. The moth is an exceedingly strong, swift flier, and may 

 travel hundreds of miles under favorable conditions. The occasional 

 notable swarms are the progeny of the first, second, or third summer 

 broods. The larva is a naked, dark-colored caterpillar, with nar- 

 row pinkish or whitish longitudinal stripes. 



The fall army worm resembles the true army worm so 

 closely that even the entomologist is sometimes in doubt 



