WSU Extension

Hortsense

Cherry : Apple-and-thorn skeletonizer
(revision date: 5/7/2015)


Biology
The adult of the apple-and-thorn skeletonizer is a small dark-brown or reddish-brown moth. The skeletonizer overwinters as a pupa or an adult, with the females laying eggs in the spring. The caterpillars are yellow-green in color, have black spots and brown heads, and feed on the leaves of several plants including apple, crabapple, pear, and hawthorn. Caterpillars are about 1/2" long at maturity. Characteristic damage includes skeletonized leaves, or leaves that are rolled into a cone and tied with webbing. Damaged leaves are brown and papery and drop prematurely.
Management Options

Non-Chemical Management
  • Hand-pick and destroy caterpillars when practical.
  • Pinch caterpillars inside rolled leaves or prune and destroy heavily infested twigs.
  • Naturally-occurring enemies help control populations of apple-and-thorn skeletonizers. Avoid use of broad-spectrum insecticides which kill beneficial insects.
Select non-chemical management options as your first choice!

Chemical Management

Bacillus thuringiensis (Bt) will provide control to young feeding caterpillars. Use a spreader-sticker with liquid Bt formulations. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Thuricide BT Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 4-226
  • Bull's-Eye Bioinsecticide
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 62719-314-56872
  • ferti-lome Borer, Bagworm, Tent Caterpillar & Leafminer Spray
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 62719-314-7401
  • Monterey Garden Insect Spray [Organic]
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 62719-314-54705
  • This list may not include all products registered for this use.
Images
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Caption: Apple-and-thorn skeletonizer
Photo by: A.L. Antonelli