Cutworm Natural Insect Control

Cutworms are the larvae (caterpillars) of several species of flying moths that are present throughout North America and a common garden pest. The larvae are called cutworms because they cut down young plants by feeding on stems at or just below the soil surface. Cutworms feed on a wide range of garden plants.

There are upwards of 20,000 species of cutworms, ranging in color from brown to black with colored splotches or stripes in shades of gray, brown, black and white. These insects have body lengths that vary from 1 to 2 inches.

Most garden cutworm damage occurs early in the season when plants are young and tender. Cutworms need not be a problem in organic gardens. They can be controlled without chemical pesticides either by limiting cutworm access to plants or with a natural pesticide.

Cutworm Collars

Cutworm collars are an effective means of controlling access to tomato plants in an organic garden.

Make collars from a smooth 3/16 inch aluminum insulation jacketing. Aluminum insulation jacketing can be found at hardware and home improvement stores in 24 or 36 inch wide rolls.

With tin snips, cut 4 inch wide strips of the aluminum insulation jacketing long enough to form a circle that will clear the stems of plants by about 1/2 inch. Wear garden gloves when handling tin to avoid cuts from sharp edges. Overlap the edges slightly and secure them with a couple of short sheet-metal screws. These durable collars can be re-used year after year.

Place a collar over each plant after planting, pushing the edge of the collar one inch into the soil and leaving 3 inches above ground.

For those who wish to avoid the expense of buying aluminum insulation jacketing, a free alternative method is using empty aluminum beverage cans to make cutworm collars. Simply cut the tops and bottoms out of the cans to make an instant collar. Be especially careful with these however as the thin aluminum will have very sharp edges.

Natural Pesticide

For the control of cutworms on plants that do not lend themselves to cutworm collars, Bacillus thuringiensis (Bt) is a widely available, natural occurring bacterium that is a very effective natural pesticide for controlling not only surface feeding cutworms but climbing cutworms as well. The kurstaki strain of Bt is applied as a spray to control cutworms. Bt has a limited spectrum of activity and does not kill beneficial insects. It is essentially nontoxic to people, pets and wildlife making it safe to use in comparison to chemical pesticide that can have adverse effects.

Bt does not kill rapidly so it often takes several days to see results. This is not a cause for concern however as insects that have consumed Bt eat little or nothing before they die.