Several species of cutworms are found in New York; the black cutworm is most commonly found in corn. The adults (moths) migrate into the state from the southern overwintering sites on the spring storms and are attracted to weeds on which they lay their eggs. One or more generations may occur per year, but it is the first generation which causes economic loss in NY corn. Cutworm larvae are large (1 to 2 inches long when fully grown), smooth, dull-colored caterpillars, which curl tightly when handled. They hide in the soil during the day and feed at night at the base of small corn plants during May and June. Symptoms include missing, cut, or wilted plants. The large, nearly mature larvae do most of the feeding damage. Each one is capable of destroying several plants, and damage may appear very suddenly as the larvae grow larger.
The key to cutworm control is to monitor emerging plants closely, particularly in fields with conditions favoring cutworm outbreaks. These conditions include late planting; weed infestations; low, wet areas; and fields previously in pasture or sod. Cutworm problems may be worse in fields planted with minimum or no tillage. Plowing, good weed control, and early planting should help reduce cutworm problems. Check fields every two or three days until plants are well established for signs of missing, cut, or wilted plants. Search for the larvae in the soil near damaged plants. Treatment is suggested (Table 3.6.1) if 5 percent or more of the plants have been cut. Cutworm larvae should be controlled while small – 1/2 inch long or less. Since the larvae are active at night, chemicals should be applied late in the day. When the soil is dry and crusted, larvae remain beneath the soil surface and will be difficult to control. Only the infested area and a 20- to 40-foot surrounding border need be treated. Direct the spray at the base of the plants. Portions of the field may need to be disked and replanted if damage has gone beyond the point of control.
Application of soil insecticides at planting does not provide effective control of cutworms despite claims by the insecticide manufacturer.
- IPM for Insect Pests of Field Corn - a free Moodle course from the NYS IPM Program
- Western Bean Cutworm identification card – including larval stages (PDF)
- Western Bean Cutworm Pest Alert, North Central IPM
- Cornell Sweet Corn Monitoring Network
- Penn State Pest Watch (Includes WBC data from NY, New England and other states)
- Ontario WBC Trap Network