Cotoneaster: Cotoneaster webworm
Photo by: C.R. Foss
Biology
The cotoneaster webworm is a dark brown caterpillar, 1/4″ to 1/2″ long. It typically ties clumps of leaves together with webbing and feeds within the nests, skeletonizing leaves.
The caterpillars feed during the summer and fall, overwintering in nests on the plant and pupating in the spring.
The dark gray, night-flying adult moth emerges in the spring to lay eggs.
The webworm is primarily a problem on Cotoneaster horizontalis (rock cotoneaster).
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!
- Hand-pick and kill caterpillars.
- Prune out and destroy nests.
- Remove any overwintering nests found on the plant.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Monitor plants and apply product 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.
Additional Image
Photo by: S.J. Collman
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.