Several species of these moth larvae are pests in the vegetable garden. The most likely pests of young cabbage plants set out early in the season are surface feeding cutworms. They spend the days hidden in the soil, and feed at night. A cutworm can sever the stems of several young plants in a single night. Adult cutworms are dark, night-flying moths with stripes on their forewings.
Apply an insecticide containing diazinon or a bait containing carbaryl around the base of undamaged plants when stem cutting is observed. Since cutworms are difficult to control, it may be necessary to repeat the application at weekly intervals. Before transplanting in an area previously full of weeds, apply a preventive treatment of an insecticide containing diazinon or the biological insecticide Bacillus thuringiensis (Bt) and work it into the soil. Further reduce damage with cutworm collars around the stem of each plant. These collars can be made of stiff paper, milk cartons, tin cans, or aluminum foil. They should be at least 2 inches high and be pressed firmly into the soil. Cultivate the soil in late summer and fall to expose and destroy eggs, pupae, and larvae.
Plant Care for Cabbage Family