Arborvitae: Leafminers
Photo by: R.S. Byther
Biology
Various species of leafminers may attack arborvitae. In general, leafminer damage is very similar to that of the cypress tip moth.
Damage is typically limited to tips of twigs, where leaves and twigs are fed upon from the inside by small larvae. Damaged leaves and twigs turn brown. Webbing and dark pellets of frass (excrement) may be visible.
Heavy infestations can cause severe damage. Similar damage from leafminers may also be seen on junipers.
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!
- Several naturally-occurring parasites help control leafminer populations. Avoid use of broad-spectrum insecticides which may kill beneficial organisms.
- Remove damaged portions of the plant to improve appearance, when practical.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
Apply thoroughly to new growth as a protective spray (follow label instructions for products applied as a drench). Apply at the end of May and again in mid-June. 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 Images
Photo by: A.L. Antonelli
Photo by: A.L. Antonelli
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