Corn: Cutworms and armyworms
categories: Corn Corn Insects Vegetables
revision date: 2023-12-02 09:17
Photo by: K. Grey
Biology
Cutworms and armyworms are the larvae of noctuid moths. These common moths are medium-sized with fairly dull coloration. The greenish, grayish, or tan caterpillars are hairless, nocturnal, and generally spotted, striped, or otherwise marked. They may be 1⁄4″ to 1″ in length and tend to curl up when disturbed. Cutworms may feed by cutting through stems of young plants an inch or less above ground level. Several plants may be damaged in one night. While armyworms typically feed during the day, cutworms spend the day just beneath the soil surface or under debris near the host. They usually feed at night, so it is advisable to search for them with a flashlight in the dark. Weeds are their primary food source.
Management Options
Use Integrated Pest Management (IPM) for successful plant problem management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Control weeds and grasses in and near the garden.
- Remove debris that may provide shelter for cutworms.
- Hand-pick night-feeding larvae, when practical. Scratch soil at base of damaged plants to find larvae in the daytime.
- Encourage natural enemies of cutworms including birds and spiders.
- Plastic or cardboard collars extending 2″ into the soil and 2″ above the soil can be placed around individual plants or groups of plants. The barrier may help prevent cutworm attack.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Bacillus thuringiensis will provide some control if caterpillars eat enough of it.
- Use a spreader-sticker with liquid Bt formulations.
- Apply other materials to the soil surface if cutworm damage is observed.
Approved Pesticides
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
Additional Image
Photo by: K. Grey