Lesser Cornstalk Borer
 Elasmopalpus lignosellus (Zeller), Pyralidae, LEPIDOPTERA

DESCRIPTION

Adult - The moth has a wingspan of nearly 25.5 mm. The male's front wings are brownish yellow and have grayish margins with several dark spots. The female's front wings are nearly black.

Egg - The egg is greenish-white and less than 1 mm in diameter.

Larva - The larva is a slender, bluish-green, brown-striped caterpillar up to 19 mm long. Color plate.

Pupa - The pupa is brownish and about 8.5 mm long.

BIOLOGY

Distribution - Although the lesser cornstalk borer is found from Maine to southern California, the bulk of its damage occurs in the southern states, particularly Alabama, Georgia and South Carolina. It is also found in Mexico, Central America and South America.

Host Plants - The lesser cornstalk borer prefers corn, but it also feeds on beans, cowpeas, crabgrass, Johnson grass, peas, peanuts, sorghum, soybeans, and wheat.

Damage - The larva of this small moth has been sporadically injurious to the seedlings of many plant species, and seems to be on the increase in the South. Injury is caused when the larva bores into the stalk of the host plant, thereby disrupting the growing point. Damage can be slight, or it can kill the plant. Damage is most prevalent during drought conditions in crops grown on sandy soil.

Life History - These borers hibernate as larvae or pupae. In North Carolina, they usually overwinter as larvae which develop into pupae before spring. The moths emerge early in the spring and lay their eggs on the host's leaves or stems. The eggs hatch in about a week. The larvae feed first on the leaves or roots. Later they construct underground silken tubes or burrows from which they bore into plants near the ground line. They become fully grown in 2 to 3 weeks, leave their burrows, and spin silken cocoons under trash on the surface of the ground. In these cocoons, they change to pupae from which moths emerge in 2 to 3 weeks. Two generations are known to occur in most southern states.

CONTROL

Cultural practices, such as clean cultivation and weed destruction along fence rows, have long been recommended for lesser cornstalk borer control. Recent research findings in Georgia, however, indicate that cultivation promotes, rather than retards, injury by insect. The fact that damage by the lesser cornstalk borer is rare under no-tillage cropping systems has been attributed to increased soil moisture and the presence of decaying organic matter. Under conventional cropping systems, the cultural practice of late fall plowing may still be of some benefit since it kills overwintering life stages. For more specific control information, consult the current North Carolina Agricultural Chemicals Manual.