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Identification of the Most Common Cutworms

March 16, 2023

Image courtesy of Frank Peairs, Colorado State University, Bugwood.org.

ARMY CUTWORM

Description: Mottled pale greenish grey to brown larvae with a broad whitish dorsal stripe along back with light brown head and darker spots.

Range: Western North America, east to Michigan, more common in arid west and prairies.

Host Plants: Small grains, canola, mustard, flax, alfalfa, sweet clover, pea, cabbage, sugar beet, various weeds (notably stinkweed) and grasses.

Life Cycle: Overwinters as larvae. Adults over summer in mountain areas and migrate back in the fall to prairie regions. One generation per year.

High Threat Situations: Outbreaks are often preceded by an abnormally dry July and wet fall.

Pest Status: Major pest.

Type of Injury: Above-ground cutworm. Smaller larvae chew holes in leaves and notch leaf margins. Larger larvae consume entire plant.

Image courtesy of Roger Schmidt, University of Wisconsin, Bugwood.org.

BLACK CUTWORM

Description: Larvae are black-pale gray with a grainy feeling skin, with a dark brown head. There are pairs of dark tubercles (wart-like bumps) along the side of the body. The tubercles can distinguish black cutworms from other non-economic species. For black cutworm, the tubercle closest to the head on each body segment is approximately 1/3 the size of the tubercle closest to the rear.

Range: Major pest of corn in Midwest and eastern Canada. Typically found East of Rocky Mountains.

Host Plants: Many crops and weeds.

High Threat Situations: Weedy fields in the spring, particularly those with henbit and chickweed as they are attractive to female moths for egg laying.

Pest Status: Major pest.

Life Cyle: Does not overwinter in Midwest, as females migrate North from South Texas and Northern Mexico.

Type of Injury: Above-ground, cutting when plants are small, tunneling larger plants. Corn at growth stage V2 or V3 will be cut at ground level. Larger plants, tunneled below ground.

Image courtesy of Frank Peairs, Colorado State University, Bugwood.org.

BRISTLY CUTWORM

Description: Larvae may be green or brown, with a profusion of short hairs in each segment, faint diamond pattern on the skin with brown head that has black interlacing lines (sutures).

Range: Native to North America. Widely distributed from the southern USA and north as far as the Canadian Northwest Territories and east to Nova Scotia.

Host Plants: Alfalfa, clover, corn, tobacco, turnip, apple, grape, cottonwood, and many other species of broadleaf plants and grasses.

Pest Status: Minor pest.

Life Cyle: Overwinters in larval stage with 2 generations per year in northern part of range with multiple in southern part of range.

Type of Injury Above-ground climbing cutworm. The larvae feed near the soil surface.

Image courtesy of Whitney Cranshaw, Colorado State University, Bugwood.org.

BRONZE CUTWORM

Description: Larvae are dark brown with a bronze sheen, three yellow stripes that run the length of the body. They are relatively thick-bodied as compared to other cutworm species.

Range: North America

Host Plants: Mainly grasses, corn and small grains.

High Threat Situations: Crops following sod.

Life Cycle:
Overwinter as larvae or occasionally eggs. One generation per year.

Pest Status: Minor pest.

Type of Injury: Above ground, can climb and will cut small plants.

Image courtesy of James Kalisch, University of Nebraska, Bugwood.org.

CLAYBACKED CUTWORM

Description: Larvae are pale-gray and translucent with a gray-brown head. There are bars on the front of the head and a broad yellow-brown stripe down the back.

Range: Middle and Eastern North America

Host Plants: Roots of a wide variety of wild and cultivated plants including apple trees, cabbage, clover, corn, and tobacco. Considered a minor pest.

High Threat Situations: Crops following sod.

Pest Status: Major pest.

Life Cycle: Overwinters as partially grown larva and can cause significant damage early in the spring.

Type of Injury: Cutting - often cuts plants at soil surface.

Image courtesy of Canola Council of Canada.

CLOVER CUTWORM

Description: Velvety-black body, sometimes green, with three, broken white lines along the length of the upper surface and a broad yellowish-pink stripe along each side with light brown head.

Range: Widely distributed in North America, except for southeastern US.

Host Plants: Canola, mustard, and flax are major field crop hosts. Other hosts include cruciferous weeds, sugar beet, clover, and some forages.

Pest Status: Occasional pest.

Life Cycle:: Overwinters as pupae in the soil. Two generations per year with the first, the most damaging.

Type of Injury: Above-ground climbing cutworm, small larvae feed on underside of leaves, larger larvae feed on all plant parts.

Image courtesy of Frank Peairs, Colorado State University, Bugwood.org.

DARKSIDED CUTWORM

Description: Gray color and a white stripe along each side just above the legs, upper surface reddish with orange-brown head with dark spots.

Range: North America, north from the southern USA into southern Canada.

Host Plants: Many herbaceous and woody hosts including vegetables, cereals, canola, corn, tobacco, flax, sunflower.

High Threat Situations: Crops following weedy fields in the preceding growing season.

Pest Status: Frequent pest.

Life Cycle: One generation per year.

Type of Injury: Above-ground climbing cutworm, nighttime feeder on leaves and stems.

Image courtesy of John Glavoski, Manitoba Agriculture.

DINGY CUTWORM

Description: Pale grayish brown, with broad gray stripe down the back with light gray V-shaped patterns and four black spots on each segment.

Range: North America distributed from Atlantic to Pacific coasts, north from the southern USA into southern Canada.

Host Plants: Wide host range, with sunflower, alfalfa, corn, flax, canola, small grains the major crop host as well as many weed species.

High Threat Situations: Weedy fields in the late summer and early fall will be more attractive to females.

Pest Status: Occasional pest, particularly in cool springs.

Life Cycle:: Overwinters small larvae, and feed in fall before overwintering

Type of Injury: Climbing above-ground cutworm, highest risk is early spring feeding as larvae overwinter and begin feeding when plants are relatively small.

Image courtesy of Frank Peairs, Colorado State University, Bugwood.org.

GLASSY CUTWORM

Description: Body semi-translucent giving it a glassy appearance, greenish-white or gray with bright reddish-brown head.

Range: North America

Host Plants: Grasses; including small grains and corn.

Life Cycle: Overwinters as small larvae.

High Threat Situations: Corn planted following wheat or sod may be at higher risk.

Pest Status: Occasional pest.

Type of Injury: Below-ground cutworm: Larvae feed underground on plant crowns and roots, rarely come to the surface.

Image courtesy of Frank Peairs, Colorado State University, Bugwood.org.

PALE WESTERN CUTWORM

Description: Pale gray to greenish gray in color with yellow-brown head with two vertical black dashes.

Range: North America, but restricted to arid and semi-arid regions, most in Northern and Central plains in the US and southern prairies of Alberta and Saskatchewan in Canada.

Host Plants: Small grains preferred, others include canola, mustard, flax, corn, sugar beet, field peas, and certain weeds.

Life Cycle:: Overwinter as eggs, one generation per year.

High Threat Situations: Common annual pest, weedy fields in late summer are very attractive to females.

Pest Status: Frequent pest.

Type of Injury: Below-ground cutworm, however, young larvae feed on the surface resulting in small holes on small plants. Older larvae sever plants just below the soil surface.

Image courtesy of John Glavoski, , Manitoba Agriculture.

REDBACKED CUTWORM

Description: Broad reddish-brown line down the back with a dark center line bordered by a dark band on each side.

Range: North America, in dry open habitats.

Host Plants: Wide host range including small grains, flax, canola, corn, mustard, sunflower, sugar beet, forage legumes, and vegetables.

Life Cycle: Overwinters as an egg, one generation per year

High Threat Situations: Fields that are weedy, broadleaf perennial and winter annual weeds, in late summer are attractive females.

Pest Status: Frequent pest.

Type of Injury: Above-ground cutworm: small larvae feed on the surface of leaves resulting in small holes, larger larvae cut off leaves and sever plants just below the soil surface.

Image courtesy of James Kalisch, University of Nebraska, Bugwood.org.

SANDHILL CUTWORM

Description: Light-tan, semi-translucent, and has several pale, longitudinal stripes with a tan colored head.

Range: North America from Newfoundland to North Carolina, west to Nebraska, north to Alberta and the Northwest Territories.

Host Plants: The larvae feed on grasses including corn and small grains, various garden crops.

Life Cycle: Overwinter as a larva. There is one generation per year.

High Threat Situations: Can be very serious pest and found in sandy soils only.

Pest Status: Common pest, on sandy soils.

Type of Injury: Below-ground cutworm, feeds on roots and can cut young plants below the soil line.

Image courtesy of Frank Peairs, Colorado State University, Bugwood.org.

SPOTTED CUTWORM

Description: Upper body mottled light to dark brown or gray with dark lateral chevrons, lower body is paler in color with a yellow or orange tint with bordered irregular wavy black line. Head white or pale brown.

Range: North America, except drier regions and southern US.

Host Plants: Broad host range, including alfalfa, clover, corn, small grains, pea, sunflower, tobacco, several vegetables, and many weed species.

Life Cycle: Overwinter as larvae; with two generations in Northern range and 3 in Southern range.

Pest Status: Occasional pest.

Type of Injury: Above-ground climbing cutworm, leaf feeder, but can cut seedlings.

Image courtesy of Frank Peairs, Colorado State University, Bugwood.org.

VARIEGATED CUTWORM

Description: Body pale gray or light brown mottled with dark brown, there are at least four yellow spots along their back with a large black followed by a large yellow spot on the last segment.

Range: Global, In North America, it occurs in Mexico, up to and across southern Canada.

Host Plants: Broad host range that includes corn, bean, alfalfa, small grains, sweet clover, potato, soybean, garden crops, but prefers broadleaf plants.

Life Cycle: Moths migrate or are wind-blown from southern states with two to three larval generations per year depending on weather.

Pest Status:: Frequent pest.

High Threat Situations: Weedy fields, with broadleaf weeds are attractive to females, early warm dry springs can also increase likelihood of outbreaks.

Type of Injury: Above-ground climbing cutworm, Larvae climb plants and feed on all plant parts.

Western bean cutworm. Image courtesy Mike Weiss.

WESTERN BEAN CUTWORM

Description: Body tan or pinkish in color, two distinct black bars behind the brown-colored head.

Range: Originally western plains and prairie provinces, and has expanded range East to Pennsylvania and Ontario.

Host Plants: Primarily a pest on corn, secondarily on dry beans, and some other legumes, but not soybean. Can survive on some weeds, such as red root pigweed and nightshade.

Life Cycle: Over winters as larva in the soil. One generation per year.

High Threat Situations: Serious Pest. Corn fields that are pre-tassel during female flights, as eggs laid on upper surface of upper most leaf.

Pest Status: Frequent pest.

Type of Injury: Above-ground climbing cutworm, young larvae feed on tassels; older larvae tunnel into the ear to feed on kernels.

DUSKY CUTWORM

Description: Uniform coloration ranging from dull grayish to nearly black with pale spots; traces of pale lines along back with pale brownish head with heavy black markings.

Range: North America, extending into southern Canada and south to Mexico.

Host Plants: Grasses including oat, corn, alfalfa, clover, tobacco, various weeds.

Life Cycle: One generation per year, in Midwest it overwinters as larvae in northern areas it may overwinter as eggs.

Pest Status: Minor pest.

Type of Injury: Above-ground cutworm, larvae emerge at night take tissue from host and consume in tunnels in the soil.

YELLOW HEADED CUTWORM

Description: Dull greenish-white and somewhat semi-transparent; sides, wrinkled appearance, with reddish head and black mandibles.

Range: North America, except SE USA and the Southern High Plains. Present across the Northern Plains, Midwest, Prairie Provinces and eastern Canada.

Host Plants: Broad host range that includes small grains, corn, pea, potato, and many vegetable crops.

Life Cycle: Overwinters as larva. One generation per year.

Pest Status: Minor pest.

Type of Injury: Below-ground cutworm, feeds on roots and can cut young plants below the soil line.

Source

Floate, K.D. 2017. Cutworm pests on the Canadian Prairies: Identification and management field guide. Agriculture and Agri-Food Canada, Lethbridge, Alberta. https://publications.gc.ca/

Ostlie, K and Potter, B. 2021. Black cutworm. University of Minnesota Extension. https://extension.umn.edu/corn-pest-management/black-cutworm#other-cutworm-species-in-minnesota-corn-1187410

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Identification of the Most Common Cutworms

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