Juniper: Spruce spider mite

Biology

Foliage of plants infested with spruce spider mites is often speckled, stippled, or bleached-looking. Severely damaged leaves or twigs may drop. Some species of spider mites produce fine webbing on the plant. They may be a problem to control because of the dense foliage typical of ornamental junipers. These mites are extremely small and are easily spread by wind, birds, and people. They overwinter as eggs on the host and can begin hatching as early as April or May.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Predaceous mites and insect predators such as ladybird beetles may naturally control spider mite levels. Avoid use of broad-spectrum insecticides that kill these predators.
• Wash spider mites from plants with a strong stream of water.
• Keep plants healthy to increase pest tolerance.
• Switch to slow-release or lower-nitrogen fertilizers. High levels of nitrogen in the leaves can increase spider mite reproduction rates.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• Begin monitoring for spider mite in the late spring or especially 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.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

• Safer Brand Insect Killing Soap Concentrate II [Organic]
  Active ingredient: potassium salts of fatty acid [EPA registration number: 42697-60]
• This list may not include all products registered for this use.

Additional Image