WSU Extension


Crown gall 
European canker (Nectria canker) 
Fire blight 
Pacific Coast pear rust 
Pear trellis rust 
Powdery mildew 
Pseudomonas blossom blast and dieback 
Stony pit 
Virus diseases 
Apple-and-thorn skeletonizer 
Brown marmorated stink bug 
Codling moth 
Cutworms and armyworms 
Pear psylla 
Pear slug (pear sawfly) 
Pearleaf blister mite 
San Jose scale 
Spider mites 

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Caption: Pear psylla
Photo by: E.C. Burts
Pear : Pear psylla
(revision date: 3/22/2021)

The brownish-gray adult pear psylla is about 1/10" long, with clear wings held rooflike over the body. The wings may have a smoky gray spot halfway along the inner margin. The red-eyed nymphs range in color from yellow to dark brown, depending on age. Pear psylla nymphs feed on leaves, preferring succulent new growth in the upper portions of the canopy. Damaged leaves may be blackened or burned in appearance. Psylla feeding produces large amounts of honeydew, a sweet, sticky material which causes russeting when it drips onto fruit. Honeydew may attract ants and often becomes covered with a growth of dark sooty mold. Psylla feeding can cause reduced vigor of trees, stunting, and fruit loss. The pear psylla spreads the organism which causes pear decline.
Management Options

Non-Chemical Management
  • Several insect predators including green lacewings, ladybird beetles, and predaceous bugs help control pear psylla populations. Avoid use of broad-spectrum insecticides which kill beneficial insects.
  • Provide proper culture to prevent susceptible flushes of succulent growth. Prune lightly, supply moderate amounts of nitrogen, and remove water sprouts and suckers.
Select non-chemical management options as your first choice!

Chemical Management

Apply oil products during the delayed-dormant season. Apply kaolin clay, insecticidal soap, or neem during the growing season as populations begin to build. As with other oil-based products, care should be taken in timing insecticide applications to early morning/late evening to minimize the potential for leaf burn during hot weather. 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.
  • Bug Buster-O [Organic]
    Active ingredient: pyrethrins  |  EPA reg no: 1021-1771-54705
  • Garden Safe Fungicide 3 Conc - OMRI - [Organic]
    Active ingredient: clarified hydrophobic extract of neem oil  |  EPA reg no: 70051-2-39609
  • Pyola Insect Spray R-T-U
    Active ingredient: pyrethrins, canola oil  |  EPA reg no: 67702-6-56872
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Safer Brand Garden Defense Multi-Purpose Spray Conc [Organic]
    Active ingredient: clarified hydrophobic extract of neem oil  |  EPA reg no: 70051-2-42697
  • Safer Brand Insect Killing Soap Conc II [Organic]
    Active ingredient: potassium salts of fatty acid  |  EPA reg no: 42697-60
  • Surround At Home Crop Protectant
    Active ingredient: kaolin clay  |  EPA reg no: 61842-18-56872
  • Whitney Farms Outdoor Insect Killer
    Active ingredient: canola oil, pyrethrins  |  EPA reg no: 67702-6-73327
  • This list may not include all products registered for this use.

+ Show larger images

Caption: Pear psylla
Photo by: E.C. Burts
Caption: Honeydew and russeting from pear psylla
Photo by: E.H. Beers