Cherry-Peachtree borer

Synanthedon exitiosa

Pest description and crop damage Peachtree borer is a clearwing moth native to North America and common in the Northwest. Adults are a metallic blue-black. The male moth may have bands of light yellow scales on the abdomen, and resembles a wasp. The female has an orange band around the abdomen. Full-grown larvae are one inch long and whitish with a brown head. Larvae burrow into the bark of the crown and feed on the cambium. Feeding is restricted to an area a few inches above and below the soil line. Young trees can be girdled completely and killed. Older trees are rarely girdled, but the feeding reduces vigor and makes them vulnerable to other pests and diseases. Infested trees bleed frass-infested gum during the growing season.

Biology and life history The borer overwinters as a larva on or under the tree bark, usually below ground. As temperatures rise above 50°F in the spring, the larva resumes feeding on the tissues under the bark. At maturity in May and June, the larva pupates. Adult moths emerge beginning in June and continue through September. Eggs are laid quickly after mating, and the young larvae hatch after 8 to 10 days and bore immediately into the base of the tree. Larvae in the bark above the soil line usually do not survive the winter in cold areas.

Pest monitoring This insect can do substantial damage if not controlled-one larva can kill a small tree. Therefore, the finding of a single larva justifies action in a small home orchard.

Management-biological control

Several wasp species are parasitic on the larvae or pupae of the borer.

Management-cultural control

Protect the base of the tree from larval entry by placing a cone around it before egg laying begins. Light metal or flexible plastic works. The cone should be pushed 1 to 2 inches into the soil and should fit snugly around the trunk at the top to prevent the tiny larvae from getting beneath it. Budding tape or other flexible material will help seal the top.

Alternatively, if there are only one or a few peach trees in a home orchard, it is quicker and cheaper to control this insect by worming. Use a pocket knife or some pointed instrument to remove dirt around the tree and dig out the larvae.

Management-chemical control: HOME USE

  • gamma-cyhalothrin-Highly toxic to bees.
  • lambda-cyhalothrin-Highly toxic to bees.
  • pyrethrins-Some formulations are OMRI-listed for organic use. Highly toxic to bees.
  • zeta-cypermethrin-Highly toxic to bees.

Management-chemical control: COMMERCIAL USE

Growing-season sprays

Direct sprays to the trunks and bases of trees. A full dilute drenching spray gives best control.

  • esfenvalerate (Asana XL) at 4.8 to 14.5 fl oz/A. REI 12 hr. PHI 14 days. Extremely toxic to fish and aquatic invertebrates; avoid spray drift and runoff to surface waters.
  • lambda-cyhalothrin (Warrior II) at 1.28 to 2.56 fl oz/A. REI 24 hr. PHI 14 days. May disrupt beneficial mite populations. Extremely toxic to fish; avoid spray drift and surface runoff.
  • permethrin (Pounce 25WP) at 6.4 to 12.8 oz/A. REI 12 hr. PHI 3 days. Extremely toxic to fish and aquatic invertebrates; avoid spray drift and runoff to surface waters.