March 2, 2018

Identification of Cutworms

Figure 1. Army cutworm. Frank Peairs, Colorado State University. Bugwood.org.

Army Cutworm

Region: West of the Mississippi River.
Larvae are grayish-black with patterns of gray and brown stripes down the length of the abdomen.
Host plants include wheat, barley, mustard, alfalfa, vegetables, and various weeds.

Figure 2. Black cutworm next to clipped corn seedling.

Black Cutworm

Region: North America
Causes the most economic damage of all cutworm species.
Larvae are black-pale gray with a greasy appearing texture and convex granules on the abdominal segments. They vary in size from 1/8-inch to 2 inches.³
Common in weedy, no-till and late-planted corn fields.
Host plants include corn, vegetables, cotton, tobacco, and weed species.
Damage: small irregular holes in the leaves; later instars may cut stems below the soil surface resulting in plant death.³

Figure 3. Bristly cutworm. Frank Peairs, Colorado State University. Bugwood.org.

Bristly Cutworm

Region: East of the Mississippi River, also LA, NM, CO, KS, NE, and TX
Causes the most economic damage of all cutworm species.
Larvae are dull gray-brown with stripes along the sides with stiff protruding hairs and dark diamond-shaped markings on their back.
Larvae feed near the soil surface, mostly on non-cultivated plants, hay, grasses, and legumes.
Host plants include corn, vegetables, cotton, tobacco, and weed species.
This species is a minor pest for corn, although occasionally it can cause heavy damage.

Bronzed Cutworm

Region: All states except Gulf states, Utah, and Wyoming
The larvae are dark shiny bronze with four brown and three yellow stripes, extending the length of the body.
Economic problems in corn can occur when it is planted into sod or pasture grasses.
Feeding occurs at the soil surface on young corn plants and in the crowns of grasses.

Figure 5. Claybacked cutworm. James Kalisch, University of Nebraska, Bugwood.org.

Claybacked Cutworm

Region: Northcentral and eastern United States.
Larvae are pale gray and translucent with gray-brown head, bars on the front of the face, and a broad yellow-brown stripe on the back.
Larvae can be very destructive to seedling corn. Small larva eats the leaf from tip to base, larger larva cut the leaves/plants just above the ground and drag them into a burrow to feed on.

Figure 6. Dingy cutworm. Frank Peairs, Colorado State University. Bugwood.org.

Dingy Cutworm

Region: Southern Canada extending south to Utah and east to Virginia.
Larvae are gray to reddish brown, abdominal segments have gray V-shaped markings on their back.
Mature larvae are about 1-inch long.
Host plants include vegetables, clover, alfalfa, tobacco, wheat, corn, grasses, and broadleaf weeds.
It rarely feeds on corn, but when it does, it usually nips the ends of young corn leaves.

Figure 7. Pale western cutworm. Frank Peairs, Colorado State University. Bugwood.org.

Pale Western Cutworm

Region: Great Plains, Texas Panhandle, westward to Rocky Mountains
Larvae are yellow-brown with green-gray stripes along the back and sides. The head is amber to black with a black, inverted V marking on the front of the head.
Host plants include wheat, oat, corn, barley, alfalfa, and sunflower.
Cutworm burrows into the soil feeding on the stem below the soil surface. The greatest amount of injury usually occurs from April to June in dryland crops.

Figure 8. Sandhill cutworm. James Kalisch, University of Nebraska. Bugwood.org.

Sandhill Cutworm

Region: Sandy soils
Larvae are white to pale gray with faint white stripes on the back and sides and the head is dull red-brown in color.
Larvae are seldom seen above the ground surface because they feed on the underground plant parts.

Figure 9. Variegated cutworm. Frank Peairs, Colorado State University. Bugwood.org.>

Variegated Cutworm

Region: All states
They can attack forest trees, vegetables, and field crops including corn, alfalfa, clover, cotton, sunflower, tobacco, and wheat.
Larvae vary in color and have a line of pale yellow dots along the back.
Larvae can feed on corn leaves and may eat the center of the stalk down to 2 to 3 inches below the ground, or often cut plants near the soil surface.

For more information on cutworm management consider reading Management of the Most Common Cutworms.

Sources:

¹Hein, G.L., Campbell, J.B., Danielson, S.D., and Kalisch, J. 1993. Management of the army cutworm and pale western cutworm. G1145. University of Nebraska Extension.

²Bailey, W. Black cutworm monitoring and forecasting program. University of Missouri.

³ Black Cutworm. Purdue University. https://extension.entm.purdue.edu

⁴Steffy, K., Rice, M., Andow, D., Gray, M., and Van Duyn, J. 1999. Handbook of corn insects. Entomology Society of America.

⁵ Peairs, F.B. 2010. Caterpillars in small grains. Colorado State University Extension.

Web sources verified 2/9/18

ID 180218110644

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Identification of Cutworms