The multi-pest complex is a collection of lepidopteran corn pests that can cause significant economic losses due to their erratic appearance, abundant numbers and the destruction they create throughout the growing season. Read more >>
Black Cutworm
Description: The black cutworm is black to pale gray. The larvae can be up to 1.5 inches long, have grainy sandpaper-like skin and four wart-like bumps along the top center of each body segment. The inside pair of bumps is two- to three-times smaller than the outside pair.
Plant Damage: The smaller black cutworm larvae feed on leaves, whereas larger larvae can cut or drill directly into the corn plants. Corn is susceptible to black cutworm damage from emergence to 15 inches in height. A cut plant may be flat on the ground or look like it is stuck into the ground at an odd angle, and it usually will discolor as it begins to wilt.
Infestation Window: April to May
Stalk Borer
Description: Young larvae are purple to black and have five longitudinal white stripes broken up in the middle of the body by a purple saddle. Fully grown larvae do not have the saddle marking and are instead uniformly dirty gray. Fully grown larvae can be 1.5 to 2.0 inches long.
Plant Damage: These larvae feed on leaves in the whorl or burrow into the base of the plant and then tunnel into the stalk. Damage caused by feeding in the whorl will first show irregular rows of holes through the unfolding leaves. In severe cases, an infested plant will have a very ragged appearance, with abnormal growth habits such as twisting, bending over or stunting.
Infestation Window: May to July
Fall Armyworm
Description: The fall armyworm can reach 1.5 inches long and is smooth-skinned. The larvae vary in color from light tan or green to nearly black and have three yellow-white lines along their backs with a wider dark stripe on each side of the yellow-white lines. Below the dark stripe on each side is a wide, wavy yellow stripe with red splotches. The head is dark brown with a white inverted “Y.”
Plant Damage: These larvae frequently damage the whorl of late pre-tassel corn. Several larvae may feed throughout the tightly coiled blades, resulting in numerous ragged holes when the blades unfurl. Large larvae may bore into stalks.
Infestation Window: July to September
Sugarcane Borer
Description: The larvae are tan with indistinct brown spots on each body segment and a black head. A stout hair originates in each of the spots. The winter form of these larvae lacks spots and has hair protruding from the location where the spot would appear in the summer larvae.
Plant Damage: These larvae feed on leaves in the whorl or they burrow into the base of the plant and then tunnel into the stalk. Damage caused by feeding in the whorl will first show irregular rows of holes through the unfolding leaves.
Infestation Window: May to July
Western Bean Cutworm
Description: Young larvae are dark brown with a faint, diamond-shaped pattern on their backs. As the larvae grow toward maturity, they lighten to a pale tan, gray-brown or pink-gray with three short, dark stripes immediately behind the head. The larvae reach a body length of 1 to 1.5 inches and can be distinguished from the corn earworm by having unnoticeable hair. In addition, the Western bean cutworm does not have stripes on its body sides like the corn earworm, and several larvae may be present on an ear.
Plant Damage: The larvae first feed on pollen and then move to the corn ears, eating and scarring kernels in the tip and along the side of the ear.
Infestation Window: Mid- to late-July
Corn Earworm
Description: Corn earworm larvae can be in many different colors ranging from yellow, brown, red and green with prominent bands of cream, pink, green or yellow running lengthwise on the body. The skin of the corn earworm is coarse and covered with microspines, and the head is usually dark yellow or orange. The larvae grow to be nearly 1.5 inches long when mature, and there is generally only one larva per ear.
Plant Damage: In more Southern areas, where infestations can occur early in the year, larvae attack the buds or central shoots of young corn and feed on the tender, unfolding leaves. These earworms may also feed on the developing tassel. In post-tassel infestations, larvae penetrate ears of corn by first feeding on silks and ear tips; then they penetrate down the ear, often eating kernels halfway down the cob.
