True Fir: Spruce budworm
categories: Conifers Ornamentals True Fir True Fir Insects
revision date: 2023-04-12 12:00
Photo by: T.J. Fitzgerald
Biology
These larvae feed on the buds and foliage and may tie shoot tips together with webbing to make a nest. They are typically green to brown in color with a darker head and grow to approximately 1″ in length. The adult is a dark gray moth. Spruce budworms are mainly pests of balsam and subalpine firs. They also attack spruces and Douglas fir. This insect is an infrequent pest in the landscape.
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-pick and destroy on small trees (where possible).
- Avoid use of broad-spectrum insecticides which may kill natural predators and parasites including parasitic wasps.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Apply insecticides in spring (May) when larvae are feeding on old needles and before they enter buds.
- June to July applications will control larvae on new growth.
- If Bt is chosen, be sure to apply when insect is feeding. The best time to apply is when caterpillars are young. Use a spreader-sticker with liquid Bt formulations.
- 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.