The adult of the apple-and-thorn skeletonizer is a small dark-brown moth. It overwinters as an adult, laying eggs in the spring. The caterpillars are yellow-green in color with black spots and brown heads. They feed on the leaves of several plants including crabapple, apple, pear, cherry, and willow. Characteristic damage includes skeletonized leaves, or leaves that are rolled and tied with webbing. The feeding caterpillars produce large amounts of webbing and small dark frass pellets (excrement).

Management Options

Non-Chemical Management

Hand-pick caterpillars.
Pinch tied leaves to kill caterpillars inside.

Select non-chemical management options as your first choice!

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

Apply if damage is noticed. Several applications may be needed during the season. Bacillus thuringiensis (Bt) will provide control of young feeding caterpillars. Use a spreader-sticker with liquid Bt formulations. Applications made in late spring and early summer for control of aphids and other insect pests often reduce this insect as well. 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 BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
Active ingredient: azadirachtin | EPA reg no: 70051-6-42697
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.

Images

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Caption: Apple-and-thorn skeletonizer Photo by: A.L. Antonelli

WSU Extension

Hortsense