Cutworms

Cutworm larvae are plump, smooth, and somewhat greasy-looking, ranging from grey to brown to nearly black. When disturbed, they characteristically curl tightly into a C-shape, a useful field clue for distinguishing them from other soil-dwelling caterpillars.

• Seedlings cut off at or just below the soil surface, often lying nearby
• Larvae curled in a tight C-shape when soil near a damaged plant is disturbed
• Damage concentrated in patches soon after planting or emergence

Adult moths lay eggs in soil or on plant debris and weeds, with timing that varies by species and region. In many temperate areas larvae overwinter in the soil, resuming feeding as temperatures rise in spring, while other species produce generations during the growing season.

Larvae pass through several instars before pupating in the soil, and depending on species and climate, one to several generations can occur each year.

Newly transplanted or emerging seedlings are the most vulnerable stage, since larvae sever stems at the soil line, killing plants outright. Established plants with thicker stems are usually far less affected.

Cutworms attack a broad range of vegetables and field crops, with maize, cabbage, lettuce, and tomato among the notable hosts.

Pre-plant scouting for larvae in soil and debris, along with checking for early cutting damage right after planting or emergence, helps identify risk before losses accumulate. Pheromone traps are available for some species to track adult moth flight, and weedy field margins are worth inspecting since egg-laying is often associated with weeds and ground cover.

Cutworm management centres on reducing conditions that attract egg-laying moths and protecting the vulnerable seedling stage.

• Control weeds ahead of planting, since they attract egg-laying moths and shelter larvae
• Scout closely in the first weeks after planting or emergence, when seedlings are most vulnerable
• Conserve ground beetles and other natural enemies
• Use physical seedling collars or barriers where practical for high-value transplants
• Consider tillage timing to disrupt overwintering or resident larvae