Pear-Armyworm and cutworm

Includes

Bertha armyworm (Mamestra configurata)
Spotted cutworm (Xestes c-nigrum)

Pest description and crop damage Several species of armyworms and cutworms attack tree fruits. The most serious pests of tree fruit in the PNW are the spotted cutworm and the Bertha armyworm. The adults are large moths ranging in color from gray to brown with spots on the wings. These moths are attracted to lights. Larvae are dirty white, reddish, gray, or black caterpillars up to 2 inches long. The larvae of these moths feed on buds and leaves, chewing holes in buds and ragged holes out of leaves. They also feed on the growing tips, particularly on small trees or in high density plantings. On larger trees, most of the feeding will be on the lower branches and may be concentrated to a few stems or limbs, while other stems are undamaged. Best time for control is early in the season.

Biology and life history Weeds are the preferred source of food for these larvae, and eggs typically are laid on weeds around the trees. Depending on species, they may overwinter as pupae or larvae in the soil. The larvae spend the day in the soil, then climb up the tree during the night to feed, often following the same path.

Management-cultural control

Control weeds, grasses, and debris in the orchard that provide cover. Encourage natural enemies of cutworms like birds and spiders.

Home orchardists: Hand-pick cutworm larvae, using a flashlight to find them, if practical. Caterpillars can be trapped by tying plastic wrap tightly around branches and trunk, then applying Tanglefoot or a similar sticky material to the plastic wrap. Remove these in the fall.

Management-chemical control: HOME USE

  • acetamiprid (armyworm only)
  • azadirachtin (neem extract)-Products containing neem extract may be phytotoxic to some pear cultivars. Some formulations are OMRI-listed for organic use.
  • Bacillus thuringiensi var. kurstaki (Btk)-Cutworm only. Some formulations are OMRI-listed for organic use.
  • Beauveria bassiana-Some formulations are OMRI-listed for organic use.
  • bifenthrin-Highly toxic to bees.
  • carbaryl-Highly toxic to bees.
  • esfenvalerate-Highly toxic to bees.
  • gamma-cyhalothrin-Highly toxic to bees.
  • imidacloprid-Cutworm only. Soil drenches may have residual activity in woody plants lasting for 12 or more months. If short-term management is the goal, consider other approaches.
  • insecticidal soap-Some formulations are OMRI-listed for organic use.
  • kaolin-Applied as a spray to foliage, stems and fruit, it acts as a repellent to some insect pests. Some formulations are OMRI-listed for organic use
  • lambda-cyhalothrin-Highly toxic to bees.
  • permethrin-Highly toxic to bees.
  • pyrethrins-Some formulations are OMRI-listed for organic use.
  • spinosad-Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin-Highly toxic to bees.

Management-chemical control: COMMERCIAL USE

  • Chemical control for armyworms and cutworms is generally not required in commercial pear orchards.