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Caption: Apple-and-thorn skeletonizer
Photo by: A.L. Antonelli
  
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Ornamental Cherry : Apple-and-thorn skeletonizer
(revision date: 6/26/2015)


Biology
The apple-and-thorn skeletonizer is a yellow-green caterpillar with small black spots. As a young caterpillar it feeds on the underside of leaves. More mature caterpillars move to the upper surface of the leaf, use silk to tie the edges of the leaf together near the base, and feed inside the tent-like structure. Leaves are skeletonized, with all tissues eaten away except veins and the lower leaf surface. Skeletonized leaves turn brown and drop. The feeding caterpillars produce large quantities of webbing and frass (excrement). The adult apple-and-thorn skeletonizer is a small dark-brown moth. Apple, birch, hawthorn, mountain ash, and willow may also be attacked.
Management Options

Non-Chemical Management
  • Remove caterpillars by hand. Pinch tied leaves to kill caterpillars.
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.
  • 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
  • Safer Brand Caterpillar Killer for Trees, Shrubs & Vegetables Conc II [Organic]
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 70051-106-42697
  • Safer Brand Caterpillar Killer/Trees, Shrubs, & Vegetables Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 42697-23
  • This list may not include all products registered for this use.
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Caption: Apple-and-thorn skeletonizer
Photo by: A.L. Antonelli