226 MANUAL. OF VEGETABLE-GARDEN INSECTS 



the crown. As far as known, corn is the only food plant of the 

 larvae, but it is probable that they also feed on the roots of 

 broom corn and sorghum. The injury to the roots inflicted by 

 the grubs, if severe, may cause the plants to remain dwarfed 

 and sickly or may merely weaken them so that few or imperfect 

 ears are produced. When many of the roots have been 

 destroyed, the corn is likely to be blown over by the wind.. The 

 larvte mature from late June to late August. They are then 

 elongate, slender, whitish grubs with the head, cervical shield 



and anal plate yellow- 

 ish brown and are 

 about f inch in length. 

 When full-grown, the 

 larva leaves the root 

 and transforms within 

 a small earthen cell to 

 a whitish pupa. The 

 beetles of the new 

 brood emerge over a 

 long period, from 

 about the first of July 

 until September. 

 They are about ^ inch 

 in length and grass-green in color with the antennae brownish, 

 paler towards the base (Fig. 140). In Illinois the eggs are mostly 

 laid between the first of August and the early part of October. 

 There is only one generation annually. The beetles feed on 

 the pollen and silk of corn and are often found on the blossoms 

 of buckwheat, goldenrod, smartweed, thistle and many other 

 wild plants as well as in the flowers of cucurbits. They some- 

 times gnaw into the unripe kernels of corn where the husk has 

 been broken and have been known to gnaw holes in the rind of 

 pumpkin and squash and to feed on the leaves of radish and 

 turnip. 



Fig. 140. 



The western corn root-worm 

 beetle (X 8). 



