WSU Extension

Hortsense

Ornamental Cherry
 
Disease
Armillaria root rot 
Bacterial canker 
Brown rot 
Coryneum blight (Shothole) 
Leaf spot 
Virus diseases 
Insect
Aphids 
Apple-and-thorn skeletonizer 
Cherry bark tortrix 
Pear slug 
Redhumped caterpillar 
Scales 
Shothole borer 
Spider mites 
Tent caterpillars 



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Caption: Pear slug and damage
Photo by: R.D. Akre
  
Ornamental Cherry : 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. The adult sawfly is a small, dark, wasp-like insect which is usually about 1/4" long. The larvae feed on the leaves of cherry, plum, 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 often drop from the tree. The pear slug has two generations per season and can be found from mid- to late spring and again in late summer.
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

Apply when sawflies and damage are noticeable. 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.
Images

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