WSU Extension


Caption: Lecanium scales
Photo by: R.S. Byther
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Filbert : Lecanium scale
(revision date: 4/4/2022)

Lecanium scales are shiny brown insects found on twigs. Adults are 1/8"-1/4" in diameter and roughly turtle-shaped. They may have light markings or appear somewhat waxy. Crawlers (immature scales) are flatter. Scales produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a growth of dark sooty mold. Heavily infested branches may be wilted, yellowish, or show other signs of stress. New growth may be stunted or lacking. Twigs and small branches may be killed. Lecanium scale is a common pest in the landscape, infesting many plants including dogwood, maple, rhododendron, willow, and most fruit trees. Lecanium scales overwinter as immatures on the host.
Management Options

Non-Chemical Management
  • Natural enemies such as ladybird beetles, green lacewings, and parasitic wasps help control scale populations. Avoid use of broad-spectrum insecticides which kill these and other beneficial insects.
  • Control honeydew-feeding ants which may protect scales from predators.
  • Hand-wipe to help control minor infestations.
  • Prune and destroy heavily infested branches, when practical.
Select non-chemical management options as your first choice!

Chemical Management

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.
  • Pyola Insect Spray
    Active ingredient: canola oil, pyrethrins  |  EPA reg no: 67702-5-56872
  • Pyola Insect Spray R-T-U
    Active ingredient: pyrethrins, canola oil  |  EPA reg no: 67702-6-56872
  • Whitney Farms Insecticidal Soap [Organic]
    Active ingredient: potassium salts of fatty acid  |  EPA reg no: 67702-21-73327
  • 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.
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Caption: Lecanium scales
Photo by: R.S. Byther