WSU Extension

Hortsense

Caption: Apple-and-thorn skeletonizer
Photo by: A.L. Antonelli
  
print version| pdf version| email url    

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


Biology
The adult of the apple-and-thorn skeletonizer is a small dark-brown moth. It 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 crabapple, apple, pear, cherry, and hawthorn. Characteristic damage includes skeletonized leaves, or leaves that are rolled into a cone and tied with webbing. Damaged leaves turn brown and drop prematurely.
Management Options

Non-Chemical Management
  • Hand-pick and destroy caterpillars.
  • Pinch caterpillars inside rolled leaves or prune and destroy infested twigs.
Select non-chemical management options as your first choice!

Chemical Management


Pesticide recommendations are for flowering (non-edible) crabapples. Apply soon after petal fall, late May, June, July and August. One or two applications however are usually enough. Bacillus thuringiensis (Bt) will provide control of 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 BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • 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
    - hide images

+ Show larger images

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