Cutworms are moth larvae that feed on garden plants at night, severing young seedlings at or just below the soil surface. They belong to the Noctuidae family, one of the largest families of moths, sometimes called owlet moths. If you’ve walked out to your garden in the morning to find a row of seedlings toppled over as if someone snipped them with scissors, cutworms are the most likely culprit.
What Cutworms Look Like
Cutworms are soft-bodied caterpillars, typically 1 to 2 inches long when fully grown. Their colors range from gray and brown to greenish or nearly black, often with faint stripes or spots running along their bodies. The adults are medium-sized moths with mottled brown front wings that blend easily into bark and soil.
One reliable way to identify a cutworm is its defensive posture. When disturbed, the caterpillar curls tightly into a C-shape and stays motionless. You’ll almost never see them out in the open during daylight. They spend the day buried just below the soil surface or tucked under dirt clods and plant debris, which is why cutworm damage is far more commonly seen than the caterpillars themselves.
How They Feed
Cutworms are strictly nocturnal feeders. After dark, they emerge from the soil and chew through the stems of seedlings and young transplants right at ground level. A single larva can work its way down a row, clipping off several plants in one night. The result looks dramatic: otherwise healthy-looking plants lying flat on the ground, severed cleanly near the base.
Not all cutworms behave the same way, though. Entomologists group them into four broad categories based on feeding habits:
- Surface cutworms are the classic stem-cutters, feeding at or just above the soil line.
- Climbing cutworms crawl up stems to feed on leaves, buds, or even fruit higher on the plant.
- Subterranean cutworms stay below the surface and feed on roots and underground stems, stunting or killing plants without any visible cut mark above ground.
- Army cutworms travel in large groups across fields, consuming foliage as they move.
Surface cutworms cause the most recognizable damage in home gardens, but climbing species can be just as destructive on taller, established plants.
Plants Most at Risk
Cutworms are generalists. They feed on a wide range of vegetables, flowers, and field crops. Seedlings and young transplants are the most vulnerable because their stems are tender and thin enough for a larva to chew through in seconds. Tomatoes, peppers, lettuce, cabbage, beans, corn, and many other common garden crops are all fair game. Once plants mature and develop thicker, woodier stems, surface cutworms pose much less of a threat, though climbing species can still cause leaf and fruit damage.
Life Cycle
Adult moths mate and lay eggs on low-growing vegetation or plant debris. The eggs hatch in 5 to 10 days. The larvae then pass through six growth stages over roughly 28 to 35 days, depending on temperature, getting larger and hungrier with each stage. Older larvae are the ones responsible for the worst damage to gardens.
When the larvae are fully grown, they burrow into the soil to pupate. In dry conditions, they may dig 3 or more inches deep. The pupal stage lasts about 12 to 15 days before an adult moth emerges to start the cycle again. In many regions, moth flights are heaviest in April and May, which means larval feeding peaks in late spring and early summer, right when most gardeners are setting out transplants. Some species produce multiple generations per year, and in late summer through fall, adult moths migrate south to overwinter along the coast.
Spotting an Infestation Early
The telltale sign is finding young plants cut off cleanly near the soil surface, often several in a row. Sometimes a cutworm chews partway through a stem without severing it completely, and the plant wilts instead of falling over. Either way, you’ll typically notice the damage in the morning after the larvae have fed overnight and retreated underground.
To confirm that cutworms are responsible, check around the base of damaged plants during the day. Brush away mulch and surface debris, or carefully dig an inch or two into the soil near the stem. The curled-up caterpillar is usually hiding within a few inches of its latest victim. Because they’re so well hidden, many gardeners go through an entire infestation without ever seeing one unless they deliberately search.
Physical and Cultural Controls
The simplest protection for transplants is a physical collar around the stem. A short section of cardboard tube (like a toilet paper roll) or a strip of aluminum foil pressed an inch into the soil and extending a couple of inches above the surface blocks cutworms from reaching the stem. This works well for small plantings of tomatoes, peppers, and similar transplants.
Keeping the garden clear of weeds and plant debris in early spring removes egg-laying sites and hiding spots. Tilling the soil before planting exposes overwintering larvae and pupae to birds and other predators. If you’re planting into a bed that was previously weedy or grassy, cutworm pressure will be higher because those conditions attract egg-laying moths.
Biological and Chemical Options
Birds, ground beetles, and parasitic wasps all prey on cutworms naturally. Encouraging these predators by maintaining diverse plantings and avoiding broad-spectrum pesticides helps keep populations in check over time.
When cutworm numbers are high enough to threaten an entire planting, targeted treatments can help. Products containing Bt (a naturally occurring soil bacterium that kills caterpillars) or spinosad (a compound derived from another soil bacterium) are effective and selective, meaning they spare most beneficial insects. Timing matters more than product choice: because cutworms feed at night and hide in soil during the day, evening applications are more likely to reach them. Bait formulations that the larvae encounter on the soil surface as they emerge after dark tend to work better than sprays applied to foliage they may never climb.
Hand-picking is also surprisingly effective in smaller gardens. Go out with a flashlight after dark, and you can often find cutworms actively feeding at the base of plants. A few nights of picking can dramatically reduce damage during the critical transplant window.