True Fir: Balsam twig aphid
categories: Conifers Ornamentals True Fir True Fir Insects
revision date: 2023-04-04 12:00
Photo by: A.L. Antonelli
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, or (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
Use Integrated Pest Management (IPM) for successful plant problem management.
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
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- 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
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.