E-48
DEPARTMENT OF ENTOMOLOGY
field crop insects

CUTWORMS IN CORN
C. Richard Edwards and F. Thomas Turpin, Extension Entomologists

The black cutworm is the most commonly observed species of cutworm that causes damage to corn plants in Indiana. Other damaging cutworms are the bristly, bronzed, clayback, dark-sided, dingy, glassy, spotted, and sandhill.

RECOGNITION OF POTENTIAL PROBLEM
The primary indicators of a potential cutworm problem are: a heavy moth flight, egg-laying, and larvae hatching just prior to corn planting. Although it is difficult to predict a cutworm infestation in a specific field, research indicates that several field conditions increase the probability for a cutworm problem. These conditions include the following: early spring weed cover prior to planting, corn following soybeans, and fields located adjacent to heavy permanent vegetation, such as woodlands, ditches, etc.
Cultural practices and environmental situations that contribute to these field conditions include: reduced tillage, a late, wet spring, or fields with poor drainage, which delays spring tillage. Because cutworms are opportunistic pests that prefer to feed on many weed species, they will feed on corn after weeds are killed or removed. Research indicates that destroying weeds with herbicides and/or tillage 7 or more days prior to planting may diminish the chances of cutworm damage because the cutworms starve before the corn emerges. Thus, producers with "high-risk" fields may wish to alter the timing of tillage/herbicide applications to reduce the potential for cutworm damage in corn.

DETECTION
Cutworm moth emergence, flight, egg-laying, hatching, and larval activity are related to weather conditions. Moth flights are monitored using light traps and pheromone traps. When insect, field, and weather conditions make it necessary to begin sampling for larvae,
advisories are issued through Purdue Extension Service newsletters.
Cutworm damage may occur during April, May, and June when the corn seedlings emerge and continue until the plants are knee high. Small cutworms (early instars) may eat small holes in leaves. As cutworms grow, feeding damage characterized by lodged or cut plants may occur below, at, or above the soil surface. When feeding an inch or more underground, cutworms chew holes in the stalks, often causing plants to wilt and die. Cutworms generally feed at night and hide under clods or in loose soil during the daytime.
The success of any cutworm management program depends upon the recognition of field conditions that may favor development of cutworms, early detection of a cutworm infestation, systematic sampling, and if required, the properly timed application of an insecticide.

Black Cutworm

PURDUE UNIVERSITY COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, IN 47907