Growing your own vegetable garden is rewarding in many ways, the taste of fresh carrots or peas are certainly something delightful. Inspecting your garden frequently for insects is important to a healthy, productive garden. One insect many gardeners have issues with is cutworms, especially early in the season.
There are several species of cutworms in Minnesota that feed on common vegetable plants like beans, peppers, potatoes, tomatoes, corn, peas, and more. The cutworms species common in Minnesota are the bronzed cutworm, variegated cutworm, dingy cutworm, black cutworm, glassy cutworm, and army cutworm; all are very distinct from each other in color, stripes, or spots. Cutworm larvae will grow to a two-inch length.
Cutworms are the larvae or caterpillar stage of several kinds of night-flying moths. Adult moths do not damage the vegetable plants; it is the larvae that feed on the plants. Cutworms curl their bodies around the stem and feed on it; causing the plant to be cut off just above the soil surface. New transplants or young plants are more susceptible to cutworm damage because their stems are more tender. Damage is most severe in the early season, but cutworms are active throughout the summer. Mainly cutworms feed in the evening or night, during the day cutworms hide in plant debris.
To determine if you have cutworms, regularly check your garden, especially in the morning for damage. Damage could be a complete sever, or part of the plant stem is chewed to the point that it causes wilting to the plant. In the evening, cutworms start to become active; drag your hand over the area within one foot of the damage; the cutworms will curl up into a “C” when disturbed. If damage or larvae are discovered, you can:
• Physically remove and crush or drop the insects into soapy water
• Create barriers made of aluminum foil or cardboard collars. The collars need to extend a few inches into the soil and several inches above, physically creating a barrier so the cutworms cannot damage your plants
• Mow the edge of the garden and avoid using organic mulch down the aisles to remove potential hiding places for the cutworms
• Maintain a three to four foot buffer of dry soil along the edge of the garden to make it unattractive to cutworms
Insecticides are available, but not usually necessary in the home garden. Treatment should be applied to the stems, or foliage for the climbing cutworms in the evening before the cutworms come out for feeding. Common insecticides are carbaryl, cyfluthrin, or permethrin. CAUTION: Read all insecticide labels very carefully before buying and again before using to ensure proper application. It is especially important that the label specify recommended use on the specific plant you wish to treat, or generally on vegetables or flowers. The label is the final authority on how you may legally use any pesticide.
Inspect your gardens frequently for insects to minimize damage, and control populations before they multiply. For more information on cutworms, visit www.extension.umn.edu/garden/insects/find/cutworms-in-home-gardens/.