Cutworms attack tomato, corn, beans, and other vegetables.
Black cutworm (Agrostis ipsilon) caterpillars are gray to black with light bands on their sides and top with a brown head and are often described as greasy looking. They are thick-bodied and up to 1 inch long. The adults are medium-sized moths with a 1-1/2 inch wingspan. Their wings are dark brown to black and have a distinctive small black dagger or dart-shaped mark.
Variegated cutworm (Peridroma saucia) caterpillars are smooth, dull, and mottled. Some have four to six or seven pale spots down the middle of the back. They grow to about 1-1/2 to 2 inches long and will often curl up when disturbed. The adult moths are reddish-brown to grayish and mottled. Their wingspan is 1-3/4 to 2 inches.
Damage Caused by Cutworms
Cutworms attacks the transplants and seedlings of tomato, corn, bean, and other vegetables during the night and hides in the soil during the day. Young larvae climb the plant to eat the leaves, whereas older caterpillars eat through the stem of young plants about 1/2 inch above ground and then eat the plant. These older larvae curl their bodies around the stem to feed; thus older plants with thicker stems are less susceptible to attack.
Life Cycle of Cutworms
Black cutworm does not overwinter in Illinois. Adults migrate north each spring into Illinois from Gulf Coast states. Females will lay eggs on low-growing vegetation and plant debris. Successive generations occur all summer.
Management of Cutworms
- Caterpillars can be removed by hand and crushed or placed in soapy water.
- Remove plant debris and weeds that can act as places to hide, lay eggs, and alternate food sources.
- Collars of cardboard, aluminum foil, or metal can be placed around transplants at planting to prevent feeding.
- At the first sign of cutting, apply insecticides to the base of plants.
- Use postemergence sprays at the three- to five-leaf stage of sweet corn if 3 percent of the plants are cut and cutworms are still feeding.
- Treat asparagus spears when infestations exceed one larva per ten crowns.
- Ground applications to the base of the plants are most effective.
Contact your county Extension office for current pesticide controls.