160 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



injury. Larvae have been found attacking wheat, rye, millet and 

 Johnson grass in a similar way, the beetles seeming to be attracted 

 to fields containing Johnson grass before the corn appears, thus 

 injuring such grassy fields more severely. Injury to corn seems to 

 be worse on low, damp spots. 



Life History. The beetles hibernate over winter and are 

 among the first insects to appear in early spring, appearing by the 

 middle of March in the Southern States. Eggs are laid during April 

 in the Gulf States and from late April to early June in Kentucky 

 and the District of Columbia. The egg is dull yellow, oval, and 

 about one-fortieth inch long. The eggs are laid singly just beneath 

 the surface of the soil and hatch in from seven to ten days, those 

 laid early in the season requiring considerably longer. The 

 larvae become full grown and pupate about a month later, the 

 adult beetles of the first generation appearing during May and 

 early June in the Gulf States and in late June and early July in the 

 District of Columbia and Kentucky. Thus the complete life cycle 

 requires from six to nine weeks in the spring. Eggs are laid by the 

 first generation of beetles, the larvae being found on the roots of 

 corn from midsummer until fall, when the second generation of 

 beetles is found in October and November in Kentucky. In the 

 Gulf States there are undoubtedly three complete generations, 

 though they have not been carefully followed.* The beetles 

 assemble on clover and alfalfa in the late fall, upon which they feed 

 until winter sets in, and often come out and feed during warm 

 spells in January and February in the Southern States. 



Control. Although rotation of crops will not be as effective in 

 the control of this species as in the case of D. longicornis, it will 

 undoubtedly be found of value to avoid planting corn in succession 

 where injury is probable. By planting late after the beetles have 

 laid their eggs, injury has been avoided in Georgia. Liberal seed- 

 ing, using ten grains of seed per hill, will give a sufficient stand 

 free from attack, so that by thinning a good stand may be secured. 



* In the Northern States, where this species is not a pest of corn, but is 

 common on cucurbs and garden plants, there is probably but a single genera- 

 tion with a life history very similar to that of the striped cucumber-beetle, 

 see page 379. 



