Cutworm

Cutworms are the larval stage of various moths in the family Noctuidae (owlet moths), with several Agrotis species among the most commonly encountered in gardens and agricultural fields worldwide. The common name refers to their characteristic feeding behavior of chewing through the stems of young seedlings at or just below the soil surface, effectively "cutting" the plant down.

Unlike the boldly patterned caterpillars of many butterflies and showy moths, cutworms are typically drab, smooth-bodied, and unremarkable in appearance, an adaptation that helps them stay concealed in soil and leaf litter during daylight hours. Their nocturnal, soil-dwelling habits mean they are far more often identified by the damage they leave behind than by direct sighting.

As larvae of otherwise unremarkable brownish night-flying moths, cutworms represent a widespread and taxonomically diverse guild of ground-dwelling caterpillars found on most continents, playing a role as both herbivores of seedlings and a food source for ground-foraging birds and predatory insects.

• Plump, smooth-skinned caterpillar, typically dull gray, brown, or dull green, often with faint longitudinal stripes or mottling.
• Curls tightly into a distinctive C-shape when disturbed or uncovered, a key identifying behavior.
• Relatively hairless compared to bristled caterpillars like the woolly bear, with a somewhat greasy or smooth-looking cuticle.
• Body length roughly 25–50 mm at full growth.
• Lookalikes: armyworms are similarly smooth-bodied noctuid larvae but tend to feed above ground on foliage in groups rather than severing stems at the soil line and hiding singly in soil by day.

Cutworms occur worldwide in gardens, agricultural fields, and lawns, wherever suitable host seedlings and loose soil for daytime concealment are present. They are most active and most damaging in spring, when young seedlings are tender, hiding in the top layer of soil or under debris during the day and surfacing to feed at night.

Larvae are nocturnal feeders, remaining curled and hidden in soil or under surface debris by day and emerging after dark to chew through the base of seedling stems or foliage. This soil-surface feeding behavior, rather than climbing high on plants, is characteristic of most cutworm species, though some "climbing cutworms" do ascend plants to feed on leaves and buds at night. Cutworms serve as prey for numerous ground-foraging birds, beetles, and parasitic wasps and flies.

Development is by complete metamorphosis. Adult moths lay eggs on plant foliage or in soil; larvae hatch and feed through several instars, often overwintering as partly grown larvae or pupae in soil depending on climate and species. Pupation occurs in an underground chamber, with adults emerging as relatively plain, night-flying moths; many species produce one to several generations per year in warmer climates.