Juniper: Aphids

categories: Conifers Juniper Juniper Insects Ornamentals

revision date: 2024-06-05 08:28

Colony of black Giant conifer aphids on branch.
Giant conifer aphids on pine
Photo by: A.L. Antonelli


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

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

Non-chemical Management

Select non-chemical management options as your first choice!

  • 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.

Chemical Management

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

  • Thorough coverage of the foliage is important, including lower leaf surfaces.
  • Apply one of the following when aphids become noticeable.
  • 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.