WSU Extension

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Caption: Woolly pine aphid
Photo by: R. Portman
  
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Pine : Pine aphid
(revision date: 2/14/2019)


Biology
Pine aphids are long-legged dark green or brown aphids covered with a white, woolly material. They are found in colonies on the needles. The aphids produce large amounts of honeydew (a sweet, sticky material) which is often covered by a black growth of sooty mold. Heavy aphid infestations may cause trees to turn yellowish, but otherwise cause only minor damage.
Management Options

Non-Chemical Management
  • Avoid use of broad-spectrum insecticides which kill predators and parasites, including ladybird beetles, green lacewings, and parasitic wasps.
  • Reduce levels of nitrogen in foliage to decrease aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer.
  • Prune and destroy heavily infested branches.
  • Hose aphids from trees with a strong stream of water, when practical.
Select non-chemical management options as your first choice!

Chemical Management


Thorough coverage of the foliage is important, including thorough penetration of needle clusters. Apply one of the following if aphids begin to build up. 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.
  • Bonide Systemic Insect Control
    Active ingredient: acephate  |  EPA reg no: 239-2461-4
  • R-T-U Year-Round Spray Oil
    Active ingredient: oil/pet distillate  |  EPA reg no: 6218-78
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Safer Brand Insect Killing Soap Conc II [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 42697-60
  • This list may not include all products registered for this use.
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Caption: Woolly pine aphid
Photo by: R. Portman