210 INSECTS AFFECTING FIELD CROPS 



lowland, is an important measure. It is well, however, not to 

 follow sod or newly cleared swamp land with corn, but to plant 

 flax, potatoes, or other truck crops the first year. Swamp or grass 

 land infected with bill bugs may be burned over. 



The Corn Ear-worm. The caterpillar of this moth, which 

 belongs to the family of cut-worms, is also known as the tomato 

 fruit-worm, tobacco-bud worm, cotton boll worm, etc. (Heliothis 

 obsoleta Fab.). It gives rise to a dull olive-green or yellowish 



moth, about three-fourths of an 

 inch long. The caterpillars them- 

 selves are variable in color; they 

 are generally striped, but the 

 ground color may be light green 

 or rose color or brown or almost 

 black. When full grown they 

 are nearly one and one-half 

 inches long. 



Life History. The moth lays 

 eggs for the first brood on corn, 

 peas, beans, or almost any avail- 

 able food plant. In from three to 

 five days these eggs hatch and the 

 caterpillars of the early broods 

 attack the corn when it is about 

 knee-high. They feed in the 

 axils of the leaves. It requires 

 two and one-half weeks for them 

 to reach full size, at which time 

 they burrow from two to five 

 inches in the soil, at the base of 



FIG. 224. Details of injury to corn plant the plant. The pupa is four- 

 by bill bugs. f , , . , , , . . 



fifths of an inch long, shining 



reddish brown in color, and it gives rise to the moth in about two 

 weeks, making its complete cycle in warm weather in something 

 over one month. It may have three broods in favorable lati- 

 tudes. Winter is passed in the pupal stage. 



Injury. The caterpillars of the second and third generations 

 feed upon the silk of the corn ears, and eat out the kernels at the 

 end of the cob, furnishing favorable conditions for moulds which 

 may do further injury. 



It is estimated that the annual damage in the United States 



