Black cutworm larvae vary in color from light gray to black and are about 1 1/2 inches long when fully grown. Numerous convex skin granules give the larvae an overall shiny and "greasy" appearance. Tubercles on the body are paired, but uneven in size. Pupae are brown, spindle-shaped, and about 3/4 inch long. The adults are nocturnal moths with a robust body and wingspan of about 1 1/2 inches. The moths are dark gray, with a black, dagger-shaped marking toward the outer edge of the forewing. The inner two-thirds of the forewing is dark. The females lay ribbed, globular, white eggs in clusters of 10 to 30 near larval food sources.