Douglas Fir: Douglas fir tussock moth
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 caterpillar 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
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!
- 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: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- 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
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.
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.