University of Illinois Extension

University of Illinois Extension

Hort Answers

Insect Damage

Black Cutworm
Agrotis ipsilon

3 (1 = rare 5 = annual)
2 (1 = very little damage 5 = plants killed)
Tomato, corn, bean, and other vegetables

Plants Affected

Black cutworm caterpillars are blackish, thick-bodied, and up to 1 inch long. The adult moth has brown wings with a 1-1/2 inch wingspan.

Black cutworm attacks the transplants and seedlings of tomato, corn, bean, and other vegetables during the night and hides in the soil during the day. Young larvae climb the plant to eat the leaves, whereas older caterpillars eat through the stem of young plants about 1/2 inch above ground and then eat the plant. These older larvae curl their bodies around the stem to feed; thus older plants with thicker stems are less susceptible to attack.

Life Cycle
Moths migrate north each spring into Illinois from Gulf Coast states. Successive generations occur all summer.

Use postemergence sprays at the three- to five-leaf stage of sweet corn if 3 percent of the plants are cut and cutworms are still feeding. Treat asparagus spears when infestations exceed one larva per ten crowns. Ground applications to the base of the plants are most effective.

Related Resources
Home, Yard & Garden Pest Guide
Illinois Commercial Landscape and Turfgrass Pest Management Handbook
U of IL - Distance Diagnosis through Digital Imaging
U of IL - Plant Clinic