Cutworms: Identification, Control & Prevention

Cutworms are moth larvae (multiple species). Fall-hatched larvae overwinter in soil/woodpiles. Most damage occurs early spring when they emerge. Caterpillars, often mistaken for grubs.

Identification

Patrol at dusk/evening or on cloudy days. Colors: gray, pink, green, black; up to 2"; solid, spotted, or striped. Curl when inactive. Nocturnal feeders; hide by day.

Black cutworm (Agrotis ipsilon): dark spots, becomes dark sword-grass moth. Variegated: mottled brown, faint white stripe. Adult moths: dark wings, ~1.5" long, 1.5" wingspan. Females lay eggs in dry soil.

Damage

Chew stems at base; feed roots/foliage; cut plants below soil. Entire plants destroyed quickly. Summer: climb to tops—don't confuse with slug damage.

Control

• Plant collars: 4" cardboard around stems at transplant. Or: toilet paper tubes, halved, soil-filled, planted tube-and-all.
• Night hand-picking with flashlight; drop in soapy water; repeat.
• Coffee grounds or eggshells around plants.
• Diatomaceous earth circle.
• Late afternoon insecticide; Bt (may harm butterflies).
• Old remedies: oak leaf mulch; tansy near cabbage; hogs root them up.

Prevention

• Delay transplanting/planting 2 weeks to starve early emergers.
• End-of-season tilling/mowing destroys winter habitat.
• Attract fireflies (natural predators).
• Bird-friendly garden (predators).

Plants Affected

• Beans
• Cabbage
• Corn
• Lettuce