True Fir: Balsam twig aphid

• Categories: Conifers Ornamentals True Fir True Fir Insects
• Last review date: 2026-01-29 12:36

Biology

Balsam twig aphids feed on needles and buds of firs. Three distinct forms of the balsam twig aphid occur. Aphids may be:

1. Small and yellow green
2. Large and bluish-gray
3. Have woolly white secretions which make them appear powdery.

The aphids mat needles together and cause new growth to be deformed and stunted. Some needles are killed and drop from the tree, leaving rough twigs.

A large amount of honeydew (a sticky material excreted by the insects) is produced, which may be covered with a black growth of sooty mold.

Healthy trees will tolerate moderate infestations easily.

Management Options

See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.

Non-chemical Management

Select non-chemical management options as your first choice!

• Provide proper plant culture. Healthy plants can tolerate more insect damage.
• Avoid overfertilization. High levels of nitrogen in the foliage encourages aphid reproduction. Switch to a slow-release or low-nitrogen formula if necessary.
• Hose infested trees with a strong stream of water to wash off insects.
• Prune and destroy individual, heavily-infested branches.
• Encourage natural aphid predators, including ladybird beetles and green lacewings. Avoid use of broad-spectrum insecticides which can kill beneficial insects.

Chemical Management

• Apply in spring.
• A second application may be needed in June.
• 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

If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.

• R-T-U Year-Round Spray Oil
  Active ingredient: mineral oil
  EPA registration number: 6218-78
• Safer Brand BioNEEM Multi-Purpose Insecticide and Repellent Concentrate [Organic]
  Active ingredient: azadirachtin
  EPA registration number: 70051-6-42697
• Safer Brand Insect Killing Soap Concentrate II [Organic]
  Active ingredient: potassium salts of fatty acid
  EPA registration number: 42697-60
• This list may not include all products registered for this use.