Controlling Cutworms and Other Leaf eaters



INTRODUCTION

Cutworms are the larvae (caterpillars) of several species of night-flying moths. The larvae are called cutworms because they cut down young plants as they feed on stems at or below the soil surface. There are also species of climbing cutworms that move up plants and feed upon foliage, buds and shoots. The adults are night-flying moths and do not cause damage. Most cutworms attack a wide range of plants. Some common vegetable targets are asparagus, bean, cabbage and other crucifers, carrot, celery, corn, lettuce, pea, pepper, potato, and tomato. In addition, a few species feed on turfgrass.

Identification

The most common species of cutworm in gardens are the bronzed cutworm, variegated cutworm, black cutworm, dingy cutworm, glassy cutworm and army cutworm.

Cutworms can be quite distinct from one another. Some cutworms are a uniform color while others are spotted or striped. Some larvae are dull and others appear glossy or shiny. Cutworms curl up into a tight "C" when disturbed.

Adult moths are moderate sized, brown or black insects showing various splotches, or stripes in shades of gray, brown, black or white. They usually are about one inch with wingspans up to 1 1/2 inches across. Typically, the front wings are darker than the hind wings and are patterned.

Life Cycle

Female moths can lay hundreds of eggs, singly or in small clusters. They typically deposit them on low-growing plants and on plant residue. Migrating moths lay eggs on the soil and the larvae hatch to feed on plants. Young larvae feed on the foliage or small roots of weeds or crops until they reach about 1/2 inch in length. Emerging or newly emerged weeds can be very attractive sites for egg laying and feeding by small larvae. At this stage, they can begin feeding on seedling stems, either cutting through them or burrowing into them. Corn, peppers, tomatoes, beans, and the crucifer family are common hosts, but they will attack many kinds of herbaceous plants.

Cutworm larvae grow as large as two inches and may go through as many as three generations per year. Native cutworms overwinter in weedy areas, grassy fields or pastures. If weeds are permitted to grow in the fall after crop harvest and the fall and winter seasons are mild, large numbers of cutworms may survive to attack vegetables in the spring. Cutworm abundance and development is greatly affected by weather, especially rainfall. Moths mate and lay eggs from early spring (black cutworm) to late summer/fall (dingy, glassy, and bronzed cutworm), beginning the next generation.

Damage

Most cutworm damage occurs on vegetable seedlings early in the season when plants are small and have tender tissue. Although cutworms are active throughout the summer, they are rarely a problem after spring. Cutworm populations vary from year to tear and when 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. Some cutworms, e.g. black, bronzed, and army cutworms, can be very injurious, attacking and cutting new plants nightly.

Climbing species of cutworm, (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. 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). To verify cutworms are present, dig around the plant just under the surface. Control is more effective when the larvae are small.

Cultural

Remove weeds and plant residue to help reduce egg-laying sites and seedling weeds that nourish small cutworms. Till your garden before planting which helps expose and kill overwintering larvae. Tilling also removes plant residue, which helps to discourage egg laying.

Physical

You can control cutworms by placing aluminum foil or cardboard collars around transplants. This creates a barrier that prevents cutworm larvae from feeding on plants. When placing these collars around plants, make sure one end is pushed a few inches into the soil, and the other end extends several inches above ground. This should prevent most species of cutworms from getting to your plants.

Insecticidal

The use of insecticides in home gardens is usually not necessary. However in severe cases insectcide may be indicated. Examples of common insecticides that are effective against cutworms.

Common name: carbaryl medium contact

Common Name: cyfluthrin medium-long contact

Common Name: permethrin medium-long contact

* Long residual can persist as long as four weeks. Medium residual can persist as long as 10-14 days.

CAUTION: 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.


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