Douglas Fir: Douglas fir tussock moth
categories: Conifers Douglas Fir Douglas Fir Insects Ornamentals
revision date: 2023-04-12 12:00
Photo by: R.D. Akre
Biology
Douglas fir tussock moth larvae start at branch tips at the top of the tree and work down, feeding mainly on the new foliage and causing severe defoliation. They may be found under webbing on the branches. Severe tussock moth outbreaks are very sporadic and last usually around three years before subsiding. The larvae feed on the needles of Douglas fir, spruce, pine, larch, and true firs. They feed mainly on forest trees and are infrequent pests in the landscape. The caterpillars are distinguished by three long tufts of black hairs on their body (two in front, one in back) and lighter tufts along their back. The hairs from tussock moth caterpillars break off easily and may cause skin or respiratory irritation.
Management Options
Use Integrated Pest Management (IPM) for successful plant problem management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Parasites and other natural controls keep this pest in check most of the time.
- Prune and destroy (burn, if possible) heavily infested branches.
- Do not touch caterpillars with bare hands. Hand-pick caterpillars only with gloves.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Monitor trees and apply when caterpillars first appear.
- 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.