Douglas Fir: Douglas fir twig weevil
Photo by: Unknown
Biology
The Douglas fir twig weevil is a small, wingless, grayish-black beetle with white markings and sometimes pinkish spots. The adult lays eggs in twigs in the summer.
The larvae mine under the bark or inside twigs. Infested twigs and small branches often turn a reddish-brown and die back.
Small, stressed trees are especially susceptible to attack by the weevils, particularly in dry years.
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 culture and minimize stress for trees, especially young ones. Healthy plants are more able to withstand insect feeding.
- Prune and destroy infested twigs, burning where possible.
- Hand-pick adults to control minor infestations on small trees, where practical.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply in July to early August to seedling or small trees.
- 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.