European Corn Borer Larvae

European Corn Borer

Common: European Corn Borer

Scientific: Ostrinia nubilalis

Crop Hosts: It can feed in almost any plant large enough to enter. In the single generation area in the Midwest they feed almost entirely on corn. In the New England two-generation area they will also enter a whole range of crops including potatoes, vegetable crops and ornamentals.

Identification and Life Cycle: The insect passes the winter as a full grown caterpillar in stems of plants they eat. The worms are 3/4 to 1 inch in length and are flesh colored. In the spring the caterpillar constructs a cocoon and after pupating, the adult emerges during June and continue to come out in the northern states until August. The moths have a wing expanse of about 1 inch. They are primarily nocturnal in habit. Each female will lay about 600 eggs on the undersides of leaves. The young larvae feed in spaces between oppressed leaves and when about half grown begin to bore into the stalk and ears. There appears to be two strains. The corn borers in eastern and southern areas are a multiple-generation strain while one generation insects are found in the northern areas. The multiple strain is most destructive.

Geographical Distribution: Found in all major corn growing areas in the United States.

Damage and Treatment: European corn borer injury often results in broken tassels and in heavy infestations the stalks can break off. The spotted caterpillars bore into all parts of the stalk and can result in the complete loss of crops of early sweet corn.

Treatment should be made when insect populations and/or damage levels reach economic thresholds. Refer to local University Extension Pest Management Guidelines for specific state thresholds.