ENEMIES OF MAIZE 249 



In other cases causing prolonged and a more or less partial injury. These grubs 

 are also extremely destructive to grass lands, in some cases causing complete 

 destruction of the sod. The adult beetles also frequently cause considerable injury 

 by feeding upon the leaves of deciduous trees. No thoroughly satisfactory remedy 

 has yet been proposed for this insect 



331. Corn Root Worms. — There are two species: the western com root 

 worm and the southern corn root worm. The larva of the western corn root worm 

 is two-fifths of an inch long, about as large as a pin, body somewhat cylindrical, 

 colorless, except the head, top of the first segment and a little patch on the last 

 segment of the body, which are yellowish-brown. The injury is done by the larva, 

 chiefly during July and August, by beginning in the tip of the maize root and work- 

 ing towards the plant, devouring the inner portion of the root as it goes. It 

 pupates in the earth among or near the roots of maize. The pupae emerge in 

 August or September as grass-green beetles about one-fifth of an inch long and 

 half as wide. The beetles feed upon the pollen, 



silks and in some cases upon the soft grains at ^^^^^^^^^^^^SpC> 



the top of the ear, but usually the injury done by 



the beetle is trivial. The beetle lays clusters of ^^^^^^^ ^°^" '°°J ^°^'"' ^"'^^f* 

 - , , J- i. 1 -i r i- i.u r three times. (After Forbes.) 



five to a dozen dirty-white eggs one-fortieth of an 



inch long in the ground, one inch to six inches deep, about the maize plant during 



October and November. Only the eggs survive the winter, hatching in May and 



June. The southern com root worm is distinguished by the beetle being larger and 



having three transverse rows of four black spots on the wing covers. Since the 



larvae of these two species have no other host plant and since the eggs are usually 



laid about the hills of maize plants, a rotation of crops furnishes a simple and 



effective remedy for these insects. It is hkewise destructive only in those sections 



where maize is cultivated on the same land several years in succession. 



332. Corn Root Web-Worms. — They are the larvae of at least five species 

 of moths which lay their eggs among the grass in the summer, the larvae passing 

 the winter in a half-grown condition. They attack the young maize plant just 

 above ground, and when not at work they remain in a silken web just underneath 

 the ground at the base of the plant. The fully grown larva is about half an inch 

 long, somewhat hairy, varying in color from brown to dirty white. They pupate 

 about June first, on the fortieth parallel. They may also attack oats.l Their 

 injuries to maize may be avoided by late planting. Ordinarily, injury is to be expected 

 only where maize follows grass ; the longer the land has been in grass the greater the 

 danger. 



333. Corn Root Louse. — All plant lice are enormously prolific. During the 

 summer the wingless females of the corn root louse reproduce continuously, without 

 the intervention of the males, living young which, when a few days old, also begin 

 to multiply. Winged females appear from time to time and establish new colonies, 

 while in the fall large numbers of individuals of both sexes appear. Generally the 

 last brood lays eggs from which the spring brood is produced. Ants apparently 



« Ohio Bui 68, !>. 48. 



