Western bean cutworm larvae are not cannibalistic which may result in an infestation of multiple larvae per ear. In years with severe infestations, two or more larvae per ear may be common and, although unusual, corn ears infested with more than 20 larvae have been recorded. In these crowded situations, as much as 50-60 percent of an ear's kernels may sustain feeding damage. Infestations on Dry Beans Western bean cutworm eggs are laid on the lower surface of bean leaves, in areas with the greatest concentration of foliage. First instar larvae may disperse up to 12 feet along a row and 10 feet across rows.
Larger larvae leave the pods during the day seeking protection in the soil.
Economic injury levels for yield loss and dockage are being investigated. Sampling Corn Western bean cutworm moths can be detected with black light or pheromone traps. Most of the eggs are laid during the peak moth flight in mid to late July. Light traps should be monitored regularly until after the adult population peaks. Field scouting should be initiated when western bean cutworm moths are first noticed.