Hawthorn: Spider mites

Biology

Spider mites are tiny, eight-legged and variably colored from yellow or green to red or brown. When viewed through a hand lens, they appear as tiny moving dots. Spider mites typically feed on the underside of leaves, causing yellowish to bronze stippling or speckling. Severely infested leaves may turn yellow and drop from the tree. Fine webbing may be present on leaves or in branch crotches. Hot, dry, dusty conditions are especially favorable for development of severe spider mite infestations.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

• Predacious mites and insect predators such as ladybird beetles may naturally control spider mite populations. Avoid use of broad-spectrum insecticides that kill these beneficial insects.
• Wash spider mites from plants with a strong stream of water.
• Provide proper plant culture. Healthy plants are more tolerant of damage.
• High levels of nitrogen in the foliage encourage spider mite reproduction. Switch to a slow-release or low-nitrogen fertilizer.

Chemical Management

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

• Begin monitoring for spider mites 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 Images