Surface cutworms: These are pests of early-season vegetables and flowers, feeding on the succulent tissue of newly transplanted or emerging plants. A single surface-feeding cutworm may destroy many plants in 1 night. They chew or cut off the plant at or below the soil surface, and then hide under dirt clods or in the soil during the day. They do not eat much of the plant, but take only a few bites from the stem, often causing the plant to topple over.
Climbing cutworms: They feed aboveground on any part of the plant. Their favorite foods are the tender young leaves, buds, and flowers of vegetables and herbaceous plants. Sometimes they infest vines or climb up into the tops of fruit trees to feed on leaves or buds. In 1 night, climbing cutworms may devour all but the stem of a young plant and then move to another plant to feed.
Subterranean cutworms: These spend their lives in the soil. They feed day and night on the roots and underground stems of vegetables, sod, and grains, causing plants to wilt and die. Many other insects and diseases cause similar symptoms. Dig in the soil around the dying plant for cutworms to confirm that they are the cause of the problem.
The adults of all cutworms are dark, night-flying moths with bands or stripes on their forewings and lighter-colored hindwings. They feed at dusk on the nectar from flowers, and may be seen fluttering around lights at night.
Since cutworms feed in the soil or hide there during the day, insecticides are most effective if they are applied around the base of plants. Use an insecticide containing carbaryl or diazinon on vegetables and lawns when stem cutting or leaf chewing is observed. To control subterranean cutworms, water the soil lightly after applying the insecticide. Control cutworms on flowers with an insecticide containing diazinon. Make sure your plant is listed on the product label. Since cutworms are difficult to control, it may be necessary to repeat the dusting or spraying at weekly intervals. Before transplanting in the area, apply a preventive treatment of an insecticide containing diazinon, chlorpyrifos, or the biological insecticide Bacillus thuringiensis (Bt), and work it into the soil. Cultivate the soil thoroughly in late summer and fall to expose and destroy larvae and pupae. Further reduce damage with cutworm collars around the stem of each plant or group of plants. These collars can be made of stiff paper, milk cartons, tin cans, or aluminum foil. They should be at least 2 inches high and pressed firmly into the soil. To reduce injury from climbing cutworms, inspect your plants at night with a flashlight and pick off and destroy any cutworms you find.
