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 in length. 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 (Aza-Direct, Atrevia 3% SL)-Aza-Direct at 0.012 to 0.025 lb ai/A; Atrevia 3% SL at 0.015 to 0.03 lb ai/A. OMRI-listed for organic use.
  • Bacillus thuringiensis (Xentari, Biobit, BT NOW, Javelin)-Xentari and Biobit at 0.5 to 2 lb product/A; BT NOW at 1 to 3.5 pt/A; Javelin at 0.25 to 1.5 lb product/A. PHI 0 days. REI 4 hr. Armyworms only. Add an appropriate spreader-sticker to enhance control. Most effective on small, actively feeding larvae. OMRI-listed for organic use.
  • Beauveria bassiana GHA (BotaniGard ES, BoteGHA ES, Botanigard Optima ES, BoteGHA Optima ES, Mycotrol Optima ESO, Principle WP) BotaniGard ES, BoteGHA ES at 0.25 to 1 quart in 5 to 100 gal water/A; Botanigard Optima ES, BoteGHA Optima ES, Mycotrol Optima ESO at 0.25 to 1.25 quarts in 5 to 100 gal water/A; Principle WP at 0.25 to 1 lb of product per 100 gal/A. Adjust water volume to ensure good coverage but avoid runoff. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • 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, Shenzi 400SC, Vantacor, Plaid SC) 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, Malathion 57 EC, Fyfanon 57% EC, Martin's Malathion 57%, Gowan Malathion 8, Malathion 8-E)- Drexel Malathion 5EC, Malathion 57 EC, Fyfanon 57% EC, Martin's Malathion 57% at 1.25 lb ai/A; Gowan Malathion 8, Malathion 8-E at 1 to 1.25 lb ai/A. PHI 0 days. Limit 2 treatments per cutting. Retreatment interval 14 days. REI 12 hr. Armyworm only.
  • methoxyfenozide (Intrepid 2F, Engame, Troubadour 2F, Vexer DRV, WithStand, Insurgent) 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, Kibosh SC, Estero 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, Cortes MAXX) Mustang at 0.035 to 0.05 lb ai/A; Mustang Maxx or Cortes 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.). 2026 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.