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Cutworms

Quick facts

  • Cutworm is a generic name for the caterpillar stage of multiple species of moths.
  • Cutworms get their name because they cut down young plants as they feed on stems.
  • Seedlings are most susceptible to cutworm feeding.
  • Physical removal is effective in many cases.

Cutworms can cause serious damage to crops. Specific pest management information for black cutworms on corn and soy is available in the Crop Production section of this website.

Black cutworm (with black bumps) curled up in a ‘C’ shape
Black cutworm (with black bumps) curled up in a ‘C’ shape

How to identify cutworms

Most cutworm species look very similar.

  • Caterpillars are smooth with very few hairs and are about two inches when fully grown.
  • They typically curl into a tight 'C' shape when disturbed.
  • They can range in color from brown or tan to pink, green or gray, and black. Some cutworms are a uniform color while others are spotted or striped.
  • Some larvae are dull and others appear glossy.

Common cutworm species in Minnesota

Brown moth with patches of white markings.
Black cutworm moth
Black cutworm

The most common species of cutworm occurring in Minnesota are the bronzed cutworm, variegated cutworm, black cutworm, dingy cutworm, glassy cutworm and army cutworm.

Adults are generic, grey-brown moths.

  • Cutworms adults generally have a body length of about one inch with wingspans up to 1 1/2 inches across.
  • Moths are brown or black insects showing various splotches, or stripes in shades of gray, brown, black or white.
  • Typically, the front wings are darker than the hind wings and are patterned.

Biology of cutworms

Bronzed cutworm

Some cutworm species, including black and variegated cutworms, migrate into Minnesota from the south each year. However, dingy, bronzed, and glassy cutworms are native to Minnesota and overwinter as eggs or larvae in weedy or grassy areas.

Moths mate and lay eggs from early spring (black cutworm) to late summer or fall (dingy, glassy and bronzed cutworm).

Dull gray cutworm on green leaves.
Dingy cutworm
  • Female moths can lay hundreds of eggs, one at a time or in small clusters.
  • Many cutworms are active early in the spring when few plants are growing, and moths will lay eggs on any green plants, including weeds and cover crops.
  • Eggs are deposited on or near low-growing plants and plant residue.
  • Young larvae feed on leaves or small roots until they reach about 1/2 inch long when they move on to seedling stems by cutting or burrowing through them.
  • The number of cutworms present is controlled by weather, especially rainfall.
  • They may go through three generations per year.

Damage 

Blackish green cutworm with an orange stripe along the side, found in plant debris.
Variegated cutworm
Shiny whitish cutworm with a red head.
Glassy cutworm

Cutworms curl their bodies around the stem and feed on it. This feeding causes the plant to be cut off just above the soil surface. The number of cutworms found can vary a lot each year. When their numbers are high, there can be severe damage.

  • Black, bronzed and army cutworms can cause serious injuries, attacking and cutting new plants nightly.
  • The variegated cutworm can climb the stem of trees, shrubs, vines and garden plants and eat the leaves, buds and fruit.
  • Species such as glassy cutworms remain in the soil and feed upon roots and underground parts of the plant.
  • Cutworms feed in the evening or night and hide in plant debris or soil during the day and it is not uncommon to see damaged or clipped plants and no larvae.
  • New transplants or young plants have more chances of injury because their stems are smaller and more tender.  
  • Damage is most severe in the early season when plants are small and have tender tissue.
  • Cutworms are active throughout the summer but are rarely a problem after spring.
  • Adult moths do not damage plants. 

Cutworms are general feeders that can attack a wide range of plants.

  • Vegetables they feed on include asparagus, beans, cabbage and other crucifers, carrots, celery, corn, lettuce, peas, peppers, potatoes and tomatoes. 
  • A few species feed on turfgrass.
A curled up black cutworm next to a corn stem cut in two
Black cutworm damage to a young corn plant
Green stems, cut at the base, bending over in the soil
Cutworm damage on potato

Managing cutworms in gardens

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Managing cutworms on vegetable farms

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Authors: Marissa Schuh, Extension IPM educator; Jeffrey Hahn, former Extension entomologist; Suzanne Wold-Burkness, College of Food, Agricultural and Natural Resource Sciences

Reviewed in 2023

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