WSU Extension

Hortsense

Caption: Giant conifer aphids on pine
Photo by: A.L. Antonelli
  
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Juniper : Aphids
(revision date: 2/14/2019)


Biology
Aphids on junipers are typically fairly large (up to 1/5" long) black insects with long legs. Aphid feeding weakens plants, causes foliage to turn brown, and may kill twigs and branches or cause premature foliage drop. The aphids often occur in large dark colonies on twigs and branches. They produce honeydew, a sweet, sticky material, and may be attended and protected by honeydew-feeding ants. Dark sooty mold may grow on the honeydew, making plants appear unhealthy.
Management Options

Non-Chemical Management
  • Hand-wipe to control small, isolated infestations when practical.
  • Wash aphids from foliage with a strong stream of water.
  • Encourage natural predators and parasites, including ladybird beetles, lacewings, and parasitic wasps.
  • Control honeydew-feeding ants, which often protect aphid colonies.
  • Provide proper nutrition. High levels of nitrogen in the foliage encourages aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer.
Select non-chemical management options as your first choice!

Chemical Management


Thorough coverage of the foliage is important, including lower leaf surfaces. Apply one of the following when aphids become noticeable. plants. 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.
  • Bayer Advanced Power Force Multi-Insect Killer R-T-S
    Active ingredient: cyfluthrin  |  EPA reg no: 72155-39
  • Bonide Systemic Insect Control
    Active ingredient: acephate  |  EPA reg no: 239-2461-4
  • 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: Giant conifer aphids on pine
Photo by: A.L. Antonelli