Extension Update: Cutworms in Northeast Montana and Western North Dakota

Montana State University Extension has received reports of cutworms in Northeast Montana and Western North Dakota (Roosevelt, Sheridan, Valley and Williams County). Cutworms are moths that are native to North America with one reproductive cycle per year. The larvae of the moth is the stage that is damaging to crops. There are two main types of cutworms present in the MonDak region and both varieties may cause damage to small grains, alfalfa, canola, peas and sugar beets. Pale Western Cutworm larvae feed on the plants’ stems below the surface and can be found below the surface of the soil, 2-5 inches deep. Larvae of the Pale Western Cutworm are pale yellowish gray with two white stripes along the mid dorsal line that form a V and can reach lengths up to 1 ½ inches. The second variety, the Army Cutworm, feeds above ground at night and resides in the dry upper portions of the soil. Damage may, therefore, be visible. Army Cutworm larvae usually have a pale mid-dorsal stripe and the head is pale brown with darker brown freckles; their bodies are greenish-brown to greenish-grey with the dorsal (top) side of the body being darker than the ventral (bottom). Multiple insecticides are registered for control of cutworm and both species are susceptible to parasitic wasps. For additional information please contact your local extension office or visit msuextension.org and search for cutworm publications.