12 



FARMERS BULLETIN 835. 



Cutworm injury, Avhicli usually consists in the cutting off of the 

 plants at or a little below the surface of the ground, almost in- 

 variably occurs in the spring, beginning as soon as the first plants 

 sprout and continuing until late June or early July, by which time 

 the worms are full grown. The worms feed at night and rest during 

 the day beneath debris or in the soil from one-half to 1 inch below 

 the surface, and since in most cases they resemble the soil closely 

 in color the cause of the injury often is not apparent. However, if 



the soil surrounding the 

 culprit i)r()lxd)ly will be 



cut-off plant be examined carefully, the 

 found curled up beneath the surface as 

 shown at c in fig- 



SEASONAL HISTORY 

 OF CUTWORMS. 



The various 

 species of cut- 

 worms are known 

 under a number 

 of names, such 

 as glassy cut- 

 worm, greasy 

 cutworm, varie- 

 gated cutworm, 

 clay-backed cut- 

 worm, etc., but 

 the injuries 

 caused by them 

 are very similar 

 and their habits 

 in general are also 

 much the same. 



The parents oi cutworms are grayish or brownishmoths, or" millers," 

 which commonly occur at lights during summer evenings. Each 

 moth may lay from 200 to 500 eggs (see fig. 7, e, /), either in masses 

 or singly, in fields covered with dense vegetation, and hence the eggs 

 are to be found more often than elsewhere in cultivated fields which 

 have been in grass or weeds the preceding fall. The eggs hatch in 

 the fall, a few weeks after they are laid, usually during September, 

 and the 3'oung cutworms, after feeding on grass and other vegetation 

 until cold weather, pass the winter as partly grown caterpillars. If 

 an infested field is left to grass, no noticeable injury is likely to 

 occur; but when it is broken up and planted to corn or other wide- 

 row crops, the worms, suddenly being placed on " short rations," play 

 havoc with the newly planted crops, the nearly full-grown worms 

 feeding greedily and consuming an enormous amount of food. In 

 northern latitudes they attain full growth and stop feeding in late 



Fu;. 7. — Variegated cutworm (Pcridroma 

 h, normal form of caterpillar, side v 

 position ; d^ dark form, view of back ; 

 seen from side ; /, egg mass on twig. 



margaritosa) : a, Moth ; 

 lew ; f, same in curved 

 c, greatly enlarged egg. 



