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Cutworms

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What Do Cutworms Look Like?

dark grey, irridescent moth on light beige fabric
Adult black cutworm. Photo: NYSIPM. Click photos to see enlarged versions.

The moth family name Noctuidae is fitting for the night-flying moths we often call millers.  Adults are generally gray or brown, 1 inch long (25mm) with 1½ inch wingspans.

dark grey, hairless caterpillar curled on the broken stalk of young corn
Black cutworm larvae. Photo: NYSIPM

Their larvae aren’t any fancier: brown or dark gray, 1¼-1¾ inches long (32-44mm), and known for curling up when disturbed and being active at night.

Some of these moths overwinter in the northeast as larvae or pupae, while others fly in from the south.

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Why Should I Worry About Cutworms?

Black, hairless caterpillar sitting on soil next to a cut plantmings
Black cutworm. Photo: NYSIPM

While the adult moths are not a problem, the larvae are prone to chewing stems of young plants and transplants, essentially cutting them at the soil line.  End of plant.  Spring transplants are very susceptible. Some cutworm species have multiple generations each year; the female moths can lay hundreds of eggs on plants or plant debris of the many hosts, so cutworms are a season-long problem.

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Why Do I Have Cutworms in My Yard?

Adult cutworm moths often show up in a vegetable garden because it’s where they’ve emerged as adults, or they are looking for a food source suitable for feeding the next generation. After mating, the adult females lay their eggs. Cutworms are generalists and will eat weeds, but if you’re growing vegetables, that’s where you’ll see damage.

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How Do I Get Rid of Cutworms?

‘Collars’ placed around seedlings are the primary defense against cutworms. Push a tin can or 3-4-inch tall cardboard collars 1-2 inches into soil around seedlings and young transplants. Cultivate soil lightly around seedlings in early morning to uncover resting cutworms; destroy them. Or scout at night with a flashlight; handpick. Set out transplants later in the season when they’re larger and less vulnerable if you’ve had a chronic infestation. Weed garden well in fall, and till before planting.

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