Cutworms

It’s not uncommon to hear from home gardeners who have planted their gardens and have nice, young plants thriving. Then one morning they check the garden and find one or more plants lying on the top of the ground — having been ‘cut’ at the base (above the roots). This is a sure sign of cutworms.

Cutworms are the immature, or larval, stage of miller moths that are seen fluttering around lights on summer nights. The larvae are plump, grayish, or brown, measure 1 to 2 inches long when mature, and curl up when disturbed. The species most often observed in our gardens is the variegated cutworm (Peridroma saucia), which feeds near the soil surface and cuts stems below ground level or just above it. The larvae are called cutworms because they cut down young plants as they feed on stems at or below the soil surface.

Cutworms feed mainly at night, and they coil up to rest during the day in the soil. Some gardeners will go out at night with flashlights to check for cutworms working above ground. You can also check at dawn for cutworms. They will feed on just about all garden vegetables and flowers. Some common vegetable hosts include asparagus, bean, cabbage and other crucifers, carrot, celery, corn, lettuce, pea, pepper, potato, and tomato.

Most cutworm damage occurs on vegetable seedlings early in the season when plants are small and have tender tissue. Cutworm populations vary greatly from year to year and, when numerous, can devastate a garden. Most of the damage caused by cutworms occurs when they chew stems of young plants at or slightly above or below the soil line. Sometimes the severed plants will drop into their burrows.

Climbing species of cutworms, (e.g., variegated cutworm) can climb the stem of trees, shrubs, vines, and garden plants and eat the leaves, buds and fruit. Other species, such as glassy cutworms, remain in the soil and feed upon roots and underground parts of the plant.

Management

Regularly check your garden, especially during late afternoon and evening when cutworms are more active, so you can detect their activity when they are first present. Also inspect your plants in the morning when damage is fresh and easier to see. Watch for plants cut off near the ground or plants that are noticeably wilting (when cutworms chew on the stems but do not sever the plant). You may also detect droppings on the ground, which can indicate cutworm feeding.

Control

For non-chemical control, place a collar of stiff paper, aluminum foil or cardboard around each plant. Insert the protective collar at least 1 inch below the surface and extend it 2 to 3 inches above the soil surface around the plant. When a freshly cut plant is found, carefully dig up the soil around the plant’s remaining root-ball and destroy exposed cutworms. Sometimes more than one cutworm will be found, so do a thorough search. Deep spading in late summer or fall destroys cutworm eggs in gardens. The spading also exposes the pupae (the stage between larval and adult form) to the weather and to birds searching for food. In addition, it is important to keep weeds under control as they also can serve as food for cutworms.

You can protect plants with a residual product if you are experiencing a severe problem. Treat the stems or the foliage (for climbing cutworms). For the best results, apply insecticides in the evening. A dusting of Carbaryl (Sevin) is the preferred treatment. Caution: Read all insecticide labels very carefully before buying and again before using to ensure proper application.

For information on topics related to home grounds and gardening, contact the Limestone County Office of the Alabama Cooperative Extension System at (256) 232-5510.