WSU Extension


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Spider mites 

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Caption: Spider mites under microscope
Photo by: L.K. Tanigoshi
Cotoneaster : Spider mites
(revision date: 3/22/2021)

Spider mites are tiny, eight-legged, and of various colors from yellowish to dark to red. They may be found on the upper or lower surface of leaves and often produce a fine webbing on the leaf surface or between leaf and stem. Spider mite feeding results in a very fine yellowish speckling or stippling on the leaves. Severe infestations may cause leaf yellowing and weaken plants. Spider mite infestations are often worse during dry, dusty conditions.
Management Options

Non-Chemical Management
  • Hose mites from plants with a strong stream of water.
  • Conserve natural predators such as ladybird beetles, lacewings, and predatory mites. Avoid use of broad-spectrum insecticides which kill these beneficial predators.
  • High levels of nitrogen in the foliage encourage spider mite reproduction. Switch to a slow-release or low-nitrogen fertilizer.
  • Provide proper culture for plants. Healthy plants are more tolerant of damage, while drought-stressed plants are more susceptible.
Select non-chemical management options as your first choice!

Chemical Management

Apply early spring when mites are present. Soaps may need to be applied several times. 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 salts of fatty acid  |  EPA reg no: 42697-60
  • This list may not include all products registered for this use.

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Caption: Spider mites under microscope
Photo by: L.K. Tanigoshi
Caption: Spider mite damage on leaf
Photo by: A.L. Antonelli
Caption: Spider mite webbing
Photo by: A.L. Antonelli
Caption: Spider mites and eggs under microscope
Photo by: Unknown