WSU Extension


Cucumber, Pumpkin, Squash
Angular leaf spot 
Cucumber mosaic virus 
Curly top (Beet curly top virus) 
Pollination failure 
Powdery mildew 
Root rot 
Verticillium wilt 
White mold 
Brown marmorated stink bug 
Spider mites 
Squash bug 
Western spotted cucumber beetle 

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Caption: Spider mites under microscope
Photo by: L.K. Tanigoshi
Cucumber, Pumpkin, Squash : Spider mites
(revision date: 3/10/2017)

Spider mites are tiny, eight-legged mites which range in color from yellowish to green or red. They typically feed on the underside of leaves, causing a yellowish to bronze stippling or speckling of leaves. Severe infestations can cause entire leaves to turn yellow and may reduce yields. Spider mite feeding is usually accompanied by webbing on the underside of leaves. The mites may be visible as "moving dust" in the webbing. Mite infestations are worse in hot, dry, dusty conditions.
Management Options

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

Chemical Management

Several applications may be needed. Begin applications when mites or their damage is first observed (usually late spring).

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Azamax Botanical Insecticide, Miticide, & Nematicide [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 71908-1-81268
  • Bonide Mite X RTU
    Active ingredient: clove oil, cottonseed oil, garlic oil/powder  |  EPA reg no: 4-04001
    Active ingredient: clove oil, cottonseed oil, garlic oil/powder  |  EPA reg no: 998920-08001
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Whitney Farms Insecticidal Soap for Organic Gardening [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 67702-21-73327
  • 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 mites and eggs under microscope
Photo by: Unknown