Lesser Peachtree Borer, Synanthedon pictipes

Order: Lepidoptera

Family: Sesiidae

Description

Adult males and females resemble wasps and are similar in appearance. Lesser peachtree borer moths have clear wings and slender, dark blue bodies with pale yellow markings. They are roughly 1.3 cm or 0.5 inches long.

Unlike most moth species, lesser peachtree borer moths are active during the day. Male moths have antennae with fine tufts as well as narrow yellow bands on the second and fourth abdominal segments.

On average, female moths lay 400 eggs. The eggs are small, oval shaped and reddish brown. Mature lesser peachtree borer larvae are roughly 2.5 cm or 1 inch long with light brown heads and creamy white or pinkish bodies. 

Quick Facts

  • The lesser peachtree borer is a native moth of North America and a pest of trees that produce stone fruits (Prunus spp.) such as peach, plum and cherry.
  • This pest attacks older trees and can be found in branches, scaffold limbs, and portions of the trunk above the ground. Effective prevention is often adequate in managing this pest.
  • The peachtree borer (Synanthedon exitiosa) and lesser peachtree borer are two closely related species. Although they have similar biology, there are important differences. For more information on peachtree borer, the webpage can be accessed here.
Lesser ptb larva

Lesser peachtree borer larva (Synanthedon pictipes)
Whitney Cranshaw, Colorado State University, Bugwood.org

Lesser ptb adult

Carroll E. Younce, USDA Agricultural Research Service, Bugwood.org

Lesser peachtree borer adult

Injury on cherry tree trunk

Randy Cyr, Greentree, Bugwood.org

Injury on cherry tree trunk caused by lesser peachtree borer.

damage on tree branch

Carroll E. Younce, USDA Agricultural Research Service, Bugwood.org
Damage on tree branch caused by lesser peachtree borer.

Damage to black cherry tree

James Solomon, USDA Forest Service, Bugwood.org

Damage to black cherry tree caused by lesser peachtree borer attacking a pruning scar.

Life History and Habits

Female moths prefer laying eggs in cracks or under bark in areas that were previously damaged. Lesser peachtree borer moths will lay eggs on scaffold limbs, branches, and trunk.

Upon hatching, larvae burrow into bark through cracks caused by winter injury, pruning, or mechanical wounds. Various larval stages overwinter in galleries formed under tree bark and resume feeding the following spring. Fully developed larvae pupate in cocoons covered with frass. Before moths emerge, pupae partially move out of hiding. Pupal skins are often left protruding from bark after moths emerge.

Injury

Lesser peachtree borer infestations tend to be severe in older orchards with prior Cytospora canker infections, winter injury, or other wounds caused by pruning or machinery. Gum exuded from wounds oxidizes over time, giving older wounds a darker color. Larvae feed and enlarge underneath the bark, which causes girdling of the trunk or limb. Production of injured limbs decreases, and when fruits are produced the weakened limbs may break under the weight. It is important to note that wounds exuding clear gum without particles of wood are not due to feeding of peachtree borer.

Prevention

This pest is not usually problematic in orchards that are well maintained. Careless pruning, broken branches, sun scalds, water injury, and cracked limbs from scale infestations degrade the health of trees and makes them more susceptible to lesser peachtree borer attack. When damage is present, it is recommended to clean the damaged area of all rotten wood and debris before applying tree paint.

Monitoring

Pheromone traps are an effective tool for monitoring peachtree borer abundance. Monitoring data from traps can be used to determine the most effective time to apply insecticides. When moth flights are increasing, monitoring the number of cocoons and empty pupal cases protruding from bark near the tree base is also helpful.

Cultural Control

Hand removal of larvae is an effective option for trees near homes or residential landscapes. A knife or wire can be inserted into galleries to remove or crush larvae. However, it is important to cut bark vertically and avoid cutting more than necessary, as the additional damage to the bark may further degrade tree health.

Chemical Control

Foliar sprays are only effective when applied during egg hatch, which is best estimated with pheromone traps. Spraying should be done after the first moths are captured in traps. Sometimes multiple sprays may be warranted for older trees with cracking and sun scalded limbs since they are more susceptible to injury.

References

Bessin, R. 2019. Lesser Peachtree Borer. University of Kentucky: College of Agriculture, Food and Environment. Available https://entomology.ca.uky.edu/ef213

Virginia Tech. (n.d.). Lesser Peachtree Borer, Synanthedon pictipes (Grote & Robinson. Virginia Tech. Available https://www.virginiafruit.ento.vt.edu/lptb.html