European Corn Borer

Adult moths are pale yellow-brown with wavy darker bands across the wings. Larvae are pale pinkish-grey with small round dark spots along the body. Before tunneling begins, young larvae produce fine "shot-hole" feeding on whorl leaves, which is often the first visible sign of infestation.

Shot-hole feeding

Rows of small round holes in unfurled whorl leaves caused by early-stage larvae.

Frass

Sawdust-like larval droppings pushed out of entrance holes in the stalk or ear shank.

Entrance hole

A small, round hole marking where a larva has tunneled into the stalk or shank.

European corn borer overwinters as a mature larva inside crop residue or stalks and pupates in spring. Emerging adults mate and lay egg masses on the underside of leaves. The number of generations completed each year, from one to several, depends on regional temperature and day length.

Because development speed is closely tied to temperature, accumulated growing-degree-day totals are widely used to predict adult flight and egg-hatch timing across a season.

Young larvae feed on whorl and leaf tissue before tunneling into the midrib, stalk, or ear shank. Tunneling weakens stalks, increasing the risk of breakage and lodging, and can sever ear shanks, causing ears to drop before harvest, all of which interrupt the movement of water and nutrients within the plant.

Maize, including both field and sweet corn, is the primary host, but the pest also attacks other large-stemmed crops such as sweet pepper in some regions.

Pheromone traps track adult moth flight, while growing-degree-day models help predict egg-laying and hatch timing. Scouting focuses on whorl-stage shot-hole damage and egg masses, since this window, before larvae enter the stalk, offers the best opportunity to assess risk.

European corn borer management combines resistant genetics, monitoring, and cultural practices within an integrated approach.

• Conserve Trichogramma wasps and other natural enemies of eggs and larvae
• Use resistant hybrids where locally approved and appropriate
• Destroy or incorporate crop residue that harbours overwintering larvae
• Time scouting using growing-degree-day models to catch susceptible larval stages
• Rotate away from continuous maize where local carry-over risk is high