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Caption: Pear slug and damage
Photo by: R.D. Akre
Hawthorn : Pear slug
(revision date: 3/10/2017)

Pear slugs, or pear sawflies, are insect larvae which resemble a small greenish or black slug. They are typically 1/4" to 1/2" long, tadpole-shaped. and produce large amounts of slime. The adult sawfly is a small, dark, wasp-like insect about 1/4" long. The larvae feed on the leaves of cherry, plum, and pear trees, as well as hawthorn. Leaves are typically skeletonized, with only the veins and lower leaf surface remaining. Heavily damaged leaves may drop from the tree. The pear slug typically has two generations per season and can be found on trees from mid- to late spring and again in late summer.
Management Options

Non-Chemical Management
  • Hand-pick and destroy individual larvae, when practical.
  • Hose pear slugs from foliage with a strong stream of water.
Select non-chemical management options as your first choice!

Chemical Management

Apply if larvae are numerous or skeletonizing damage exceeds 25% of foliage. Thorough coverage is essential for products applied as foliar sprays. 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.
  • Safer Brand Insect Killing Soap Conc II [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 42697-60
  • This list may not include all products registered for this use.

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Caption: Pear slug and damage
Photo by: R.D. Akre