Pacific Northwest Insect Management Handbook

Vetch hay-Armyworm and cutworm

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Many species

Pest description and crop damage Caterpillars vary in color when full grown: 1 to 2 inches long. They feed on foliage of older plants or cut off young plants at ground level. Larvae of both commonly feed on plants at night, hiding in or on the soil surface under leaf litter by day.

Management-chemical control

  • azadirachtin (Neemix 4.5 IGR) at 0.12 to 0.30 ai/A. OMRI-listed for organic use.
  • Bacillus thuringiensis (Biobit HP) at 0.5 to 2 lb/A. PHI 0 days. Armyworms only. Add an appropriate spreader-sticker to enhance control. Most effective on small, actively feeding larvae. Some formulations are OMRI-listed for organic use.
  • Beauveria bassiana GHA (Botanigard Maxx) at 0.5 to 1 qt/100 gal. PHI 0 days. REI 4 hr.
  • Chromobacterium subtsugae (Grandevo WDG) at 1 to 3 lb product per 100 gal/A. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • chlorantraniliprole (Coragen, Prevathon) at 0.045 to 0.098 lb ai/A. Prevathon max rate is 0.067 lb ai/A. PHI 0 days. REI 4 hr. Do not exceed 0.2 lb ai/A or 4 applications per season. Make one application per cutting.
  • malathion (Drexel Malathion 5EC) at 0.625 to 1.25 lb ai/A. PHI 0 days. REI 12 hr. Armyworms only. Limit 2 treatments per cutting. Retreatment interval 14 days.
  • methoxyfenozide (Intrepid 2F) at 0.06 to 0.16 lb ai/A. PHI 0 days graze, 7 days hay. REI 4 hr. Do not exceed 0.5 lb ai/A per year. Limit one treatment per cutting.
  • spinosad (Entrust SC) at 0.031 to 0.0625 lb ai/A. PHI 0 days for forage; 3 days for hay or fodder. REI 4 hr. Do not exceed 0.186 lb ai/A per season. Do not graze cattle until spray has dried. Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin (Mustang, Mustang Maxx) Mustang at 0.035 to 0.05 lb ai/A; Mustang Maxx at 0.0175 to 0.025 lb ai/A. PHI 3 days cutting and grazing; 7 days for seed. REI 12 hr. Do not apply more than 0.05 lb ai per cutting or 0.15 lb ai per season of Mustang or 0.025 lb ai per cutting and 0.075 lb ai per season of Mustang Maxx. Retreatment interval 7 days.

Kaur, N. (Ed.). 2024 Pacific Northwest Insect Management Handbook.
© Oregon State University.

Use pesticides safely!

  • Wear protective clothing and safety devices as recommended on the label. Bathe or shower after each use.
  • Read the pesticide label—even if you’ve used the pesticide before. Follow closely the instructions on the label (and any other directions you have).
  • Be cautious when you apply pesticides. Know your legal responsibility as a pesticide applicator. You may be liable for injury or damage resulting from pesticide use.

Trade-name products and services are mentioned as illustrations only. This does not mean that the participating Extension Services endorse these products and services or that they intend to discriminate against products and services not mentioned.