Cutworms are not actual worms but the larval stage of several different moth species. They are significant pests because of the characteristic damage they inflict on young plants and seedlings. The name comes from their habit of chewing through the stems of tender plants at or just below the soil line, effectively cutting the plant down. Understanding the origin of these larvae, which begins with the adult moth, is the first step toward protecting vulnerable crops.
Identifying the Cutworm Larva
The cutworm is a plump, soft-bodied caterpillar that grows to a length of 1 to 2 inches when fully mature. Their color typically ranges from dull gray, brown, or black, though some species may show shades of pink or green, often with subtle stripes or spots. Most cutworm species appear smooth and hairless, sometimes possessing a somewhat waxy appearance.
A clear identifying feature is their defensive reaction when disturbed: they immediately curl their body tightly into a distinct C-shape. The damage they leave behind is a clear sign of their presence, typically appearing as young plants severed at the base near a small hole in the soil. While some types climb to feed on leaves, the surface-feeding varieties are the ones most known for cutting plants down.
The Adult Stage: Moths and Egg Laying
Cutworms originate from the eggs laid by various species of moths belonging to the family Noctuidae, often referred to as dart moths or miller moths. The adult moths are generally medium-sized, with wingspans ranging from 1 to 3 inches. They are usually dull gray or brownish in color with distinct markings on their forewings, and they are nocturnal, feeding only on nectar.
The female moths are the initial source of an infestation, sometimes laying hundreds to over a thousand eggs during their lifespan. Most species prefer to lay their eggs on low-lying vegetation, such as weeds, grasses, or cover crops, or on plant debris near the soil surface. This preference explains why newly tilled ground that previously held such growth can be especially vulnerable to cutworm activity. The eggs hatch relatively quickly, often within a week or two, depending on the temperature and species.
Soil Habitat and Nocturnal Movement
Once the larvae hatch, they move into the soil or under surface materials. The larvae spend the day hidden just beneath the soil surface, under plant debris, mulch, or soil clods, where they are shielded from predators and sunlight. This behavior explains why it is common to find damaged plants without seeing the pest itself.
The cutworm’s destructive phase is defined by its nocturnal movement, as the larvae emerge from their daytime shelters only after dark to feed. They crawl along the soil surface to the nearest plant stem to begin feeding, cutting through the tender tissue. Depending on the species, cutworms may overwinter in the soil as partially grown larvae, eggs, or pupae, remaining dormant until warmer temperatures prompt them to resume feeding in the early spring.