Rangeland-Armyworm and cutworm

Many species, including

Army cutworm (Chorizagrotis auxillaris)
Armyworm (Pseudaletia unipuncta)
Black cutworm (Agrotis ipsilon)
Glassy cutworm (Apamea devastator)

Pest description and crop damage Larvae are 1 to 2 inches long at maturity. All, except glassy cutworm and Protagrotis obscura usually feed above ground on foliage after dark or during conditions of low light intensity.

Management-organic control

  • Bacillus thuringiensis kurstaki (many commercial products, e.g., Dipel) at 0.5 to 2 lb product/a. PHI 0 days. REI 4 hr. Armyworms only. Most effective on small caterpillars, but use highest recommended rate for fully developed ones. Multiple applications may be necessary for effective control. A spreader sticker may improve performance.
  • spinosad (Entrust) at 0.63 to 1.25 oz/a. PHI 0 days for forage; 3 days for hay or fodder. Do not apply more than 3.75 oz of Entrust (0.186 lb ai spinosad) per acre per season or make more than 6 applications per year or 3 applications within 21 days. Follow resistance management guidelines. Armyworms only. OMRI-listed for organic use.

Management-chemical control

  • beta-cyfluthrin (Baythroid XL) at 0.013 to 0.015 lb ai/a. PHI 0 days for grazing or 7 days for hay. REI 12 hr. Do not exceed 0.089 lb ai/a per season. Armyworms only.
  • bifenthrin (Brigade 2EC) at 0.1 lb ai/a. Do not exceed 0.2 lb ai/a per season. Retreatment interval: 30 days. REI 12 hr.
  • chlorantraniliprole (Coragen) at 0.045 to 0.065 lb ai/a. REI 4 hr. Do not exceed 0.2 lb ai/a or 4 applications per season. Armyworms only.
  • gamma-cyfluthrin (Declare) at 0.01 to 0.015 lb ai/a. PHI 0 days for grazing. REI 12 hr. Do not exceed 0.045 lb ai/a per season.
  • lambda-cyhalothrin (Warrior II with Zeon Technology) at 0.015 to 0.03 lb ai/a. PHI 0 days for grazing and forage; 7 days for hay. REI 12 hr.
  • malathion at 1.25 to 1.4 lb ai/a. PHI 0 days. REI 12 hr.
  • zeta-cypermethrin (Mustang Maxx) at 0.0175 to 0.025 lb ai/a. PHI 0 days graze and hay; 7 days straw. REI 12 hr.