Therefore, infestations of black cutworms in Iowa and other northern latitudes depend on annual migrations of moths from southern overwintering sites in Texas and Mexico. Even so, black cutworms cannot survive winters in regions with freezing temperatures. Biologyīlack cutworm is native to North America and widely distributed. They are orange-brown in color but become darker brown as they develop. Pupa: Pupae are approximately ¾ inch long and are found in the soil. Black cutworm larvae (left) can be distinguished from other cutworm larvae, such as dingy cutworm (right), by examining the size of tubercles. Black cutworm larvae are 2 inches long at maturity. As a comparison, for dingy cutworm, the tubercles are roughly the same size (Photo 4). 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. The tubercles are used to distinguish black cutworms from other cutworm species that rarely cause economic injury in corn. There are pairs of dark tubercles (wart-like bumps) along the side of the body. Their skin is grainy and light grey to black, and they have a dark brown head (Photo 3). Larva: Black cutworm larvae are caterpillars with three pairs of legs near the head and four pairs of fleshy prolegs on the abdomen. Usually, adults lay eggs on dense, low-lying vegetation near larval food sources. They are typically laid in clusters of 10-30 but may be laid singly. Photo by Adam Sisson.Įgg: Eggs are white, globular, and ribbed. Black cutworm moth with more distinct markings. Wing markings are most distinct on newly emerged moths moths may be difficult to identify as they age or become damaged. Key identification features include a small black dagger mark that extends from a bean-shaped spot near the area of the wing where the light band begins (Photos 1 and 2). Forewings are dark brown to black in color with a light band at the end of each wing. IdentificationĪdult: Adult black cutworm moths are approximately 1.5 inches long. It is sporadic and unpredictable, making it essential to scout to determine whether larvae are present in a field or if management is required. Black cutworm ( Agrotis ipsilon) is a migratory pest that arrives in Iowa with spring storms each year.
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