Grape: Cutworms and armyworms

Biology

Cutworms 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. At night, cutworms climb into the plant and feed on buds and shoots. They typically spend the day just beneath the soil surface or under debris near the host. Weeds are the primary food source for cutworms.

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 around plants that provides shelter for cutworms.
• Hand-pick night-feeding larvae, when practical. Scratch soil at the 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 plants. The barrier may help prevent cutworm attack.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• Apply when first tiny worms are seen for most effective control.
• Apply weekly until threat subsides. Bacillus thuringiensis will provide some control if caterpillars eat enough of it.
• Use a spreader-sticker with liquid Bt formulations.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

• Bonide Captain Jack's Deadbug Brew R-T-U [Organic]
  Active ingredient: spinosad (spinosyn A+D) [EPA registration number: 4-472]
• Bonide Thuricide BT Concentrate
  Active ingredient: Bacillus thuringiensis subsp. kurstaki [EPA registration number: 4-226]
• This list may not include all products registered for this use.

Additional Images