224 THE PEANUT— THE UNPREDICTABLE LEGUME 



punctures. Hind margins brownish. Hindwings yellowish, with posterior margin 

 fuscous. 



Biology. Studies on biology of the corn earworm have been made by 

 numerous workers (81, 112, 13, 45). The insect over-winters in the pupal 

 stage which may be found 2 to 6 inches below the surface of the soil. The 

 adult emerges in the spring or early summer, and the females soon 

 begin depositing eggs. Eggs are laid singly on the leaves and terminal 

 buds of many plants. When corn in the silking stage is present the eggs 

 are deposited on the silks. One female may lay as many as 3,000 eggs. 

 On peanuts, the caterpillars feed on the leaves, causing ragging of the 

 foliage, or even complete defoliation of the plants. When the larva is ma- 

 ture it pupates in the soil. Time required for complete development, egg to 

 adult, is approximately 30 days under favorable conditions. 



In addition to feeding on peanuts, this insect is a major pest of several 

 other crops including sweet corn, field corn, cotton, tomatoes, tobacco, 

 soybeans and other plants. It is commonly called corn earworm, tomato 

 fruitworm, or bollworm, depending upon the crop it infests. 



The moths are most active at dusk or during warm, cloudy days. They 

 are strong flyers and may migrate for considerable distances before de- 

 positing eggs. There appears to be a tendency for the migration to be 

 northward. 



Control. The literature available on control of corn earworm is too 

 extensive to review in this paper. Winburn and Painter ( 162) reported 

 46 hymenopterous and 22 dipterous insects that aid in natural control. An 

 enormous amount of research has been conducted on the chemical and 

 cultural control of Heliothis armigera on corn, cotton, tomatoes and 

 several other crops. However, very little information is available on con- 

 trol of this insect on peanuts. Experiments conducted at the Wiregrass 

 Substation of the Alabama Agricultural Experiment Station have shown 

 that the insect may be successfully controlled on peanuts with cryolite, 

 DDT or toxaphene (5, 7, 8). The insect is most readily controlled when 

 the larvae are small. Full-grown caterpillars are somewhat resistant to 

 most insecticides. Cryolite should be used undiluted at the rate of at least 

 20 pounds per acre for control of earworms on peanuts. Two and one- 

 half percent DDT dust at the same rate is effective against small larvae. It 

 is not highly effective against mature forms. Where a population of fully 

 grown caterpillars develops before control measures are applied, a dust 

 containing at least 5 percent DDT is required for satisfactory results. Ten 

 percent toxaphene is highly effective against small larvae and moderately 

 so against mature forms. 



