Oak: Western oak looper
Photo by: S.J. Collman
Biology
The Western oak looper feeds mainly on the foliage of the Oregon white (or Garry) oak (Quercus garryana).
Mature larvae of the Western oak looper are about 1″ long and light brown with black spots when mature. They move in a characteristic “looping” or measuring-worm fashion.
The adult moth is yellowish to dark brown. Severe infestations are rare but can result in almost total defoliation of trees. No permanent damage is done by occasional outbreaks.
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!
- Severe outbreaks seldom occur.
- Provide proper culture. Healthy trees can better tolerate insect damage.
- Hand-pick caterpillars when practical.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply in July, or early August when larvae are feeding.
- It is mostly a pest in Oregon.
- If Bt is chosen, be sure to apply when insect is feeding. Best time 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
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.