Common Name: European corn borer
Scientific Name: Pyralidae: Ostrinia nubilalis
Status: A pest of field corn
Damaging Stage: Caterpillar

Biology: Adults are small, tan and about 1/2 inch in length. They hold their wings in a delta shape at rest. Females have a thick body and light-colored wings whereas the males have darker tan wings and a thinner body. European corn borer larvae are either a light tan or pink color. They have distinctive small, round brown spots on each segment. Mature larvae can reach a length of 1 inch.

European corn borers overwinter as larvae in corn stalks left from the previous growing season. As temperatures increase, the larvae enter the pupal stages for two weeks before developing into adults. The adults generally emerge in late summer. There are two generations per year.

Injury: European corn borers feed on all above-ground tissues of the corn plant. Similar to corn earworm, they attack the tassels, ears and stalks. They form nestling cavities that interfere water and nutrient movement in the plant.

Action Threshold: 1^st generation corn borer should be chemically controlled when 75% of stand is infested. 2nd generation rescue treatment is warranted when eggs or larvae are recovered on 50% or more of plants.

Management: Chemical controls are effective if they are used preventively, early in the growing season.