Corn Borer

Keep this pest from decimating your homegrown sweet corn.

January 30, 2013

Ostrinia nubilalis

Corn Borer Larvae

Corn Borer Adult

Corn Borer Eggs

Adults: females pale yellowish brown with darker zigzag patterns across wings (1-inch wingspan); males darker-colored. Larvae: beige with small brown spots, up to 1 inch. Eggs: white, overlapping, laid in masses of 15 to 20 on undersides of leaves. Found throughout northern and central United States and central and eastern Canada.


Young larvae feed on corn leaves and tassels and beneath husks. Older larvae burrow into corn stalks and ears; damaged stalks may break. Larvae also tunnel in stems or pods of beans, onions, peppers, potatoes, tomatoes, and other crops.

Life Cycle
Larvae overwinter in plant residue and pupate in early spring. Adults emerge in June; lay eggs late June to mid-July. Eggs hatch after 1 week; larvae feed for 3 to 4 weeks. One to three generations per year.

Plant resistant corn cultivars; remove tassels from two-thirds of corn plants before they begin to shed pollen; spray BTK on leaf undersides and into tips of ears; apply granular BTK or mineral oil in tips of ears; rotate crops; release Trichogramma wasps for control in large fields; attract native parasites by allowing flowering weeds to grow between rows; pull out and destroy all infested crop residue immediately after harvest. For severe infestations, spray pyrethrin when larvae begin feeding on leaves, tassels, or ears.

Larvae photo: Keith Weller, USDA Agricultural Research Service,
Adult & Moth photo: Frank Peairs, Colorado State University,

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