WSU Extension


Caption: Aphid colony
Photo by: A.L. Antonelli
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Birch : Aphids
(revision date: 3/10/2017)

Aphids are small yellowish to greenish insects often found on the underside of leaves and on new growth. Aphids on birch typically feed on the leaf veins and produce large amounts of honeydew, a sticky material which may attract ants or become covered with a black growth of sooty mold. Developing leaves which have been injured by aphid feeding may show a typical "corrugated" or wrinkled growth pattern, with the insects often found on the underside in the distortions. Some yellowing of the leaves may be observed with heavy aphid infestations.
Management Options

Non-Chemical Management
  • Hand-wipe or prune to control small, isolated infestations when practical.
  • Wash aphids from foliage with a strong stream of water.
  • Encourage natural enemies, including ladybird beetles, lacewings, and parasitic wasps.
  • Control honeydew-feeding ants, which may 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 foliage is important, including lower leaf surfaces. Apply when aphids are first noticed. 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.
  • All Seasons Horticultural & Dormant Spray Oil Conc [Organic]
    Active ingredient: oil/pet distillate  |  EPA reg no: 4-80
  • Bug Buster-O [Organic]
    Active ingredient: pyrethrins  |  EPA reg no: 1021-1771-54705
  • 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: Aphid colony
Photo by: A.L. Antonelli
Caption: Aphid cast skins
Photo by: R.S. Byther