WSU Extension

Hortsense

Caption: Pear slug and damage
Photo by: R.D. Akre
  
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Ornamental Plum : Pear slug
(revision date: 2/14/2019)


Biology
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 on their bodies. The adult sawfly is a small, dark, wasp-like insect which is usually about 1/4" long. The larvae feed on the leaves of plum, cherry, and pear trees. Leaves are typically skeletonized (the upper layers of the leaf are eaten away, leaving only the veins and the lower leaf surface). Heavily damaged leaves may drop. The pear slug can be found from mid- to late spring and again in late summer. There are two generations per year.
Management Options

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

Chemical Management


Chemical control measures are rarely necessary except for very severe infestations. Apply when larval damage approaches 25% to 30% defoliation. 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 Captain Jack's Deadbug Brew R-T-U [Organic]
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 4-472
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • 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