LEPID OP TERA . 1^1 



liated by the ' Northern Army.' " ^ During recent years 

 they have appeared several times in New England, 

 notably in 1861 and 1875. 



The life of the larva varies greatly in length, depend- 

 ing upon temperature. In St. Louis, at an average 

 temperature of 80° F., it covers a period of fifteen 

 or sixteen days. In Northern Illinois, Walsh gives the 

 period at " from four to five weeks." The last brood 

 usually hibernates in the caterpillar stage, so that in 

 this case the larval life covers four months or more. 

 The caterpillars suddenly disappear, as they usually 

 burrow in the ground and become pupae (Fig. 160). 

 In warm climates there may be sev- 

 eral broods, but in New England there 

 are probably only two. 



rr^i r ,, ,, Fig- 160. 



Ihe common name of" cutworm 

 is given to the larvEe of the Noctuid moths, particu- 

 larly to those of the genera Agrotis, Hadena, and 

 Mamestra. 



BOMBYCID^. 



This family includes the x\merican silkworm, already 

 described (see pp. 196-200), and the mulberry silk- 

 worm, Bombyx mori, which has been reared in China 

 for many centuries, and with varying success in our 

 own country for three hundred years. Teachers liv- 

 ing in the vicinity of Florence, Mass., also of Phila- 

 delphia and farther south, are favorably situated for 

 obtaining the eggs of the silkworm and watching 

 them develop. The larva will live for a time upon 

 lettuce, although it much prefers mulberry leaves. 



1 See Riley, Eighth Mo. Ent. Rep., pp. 25-29. 



