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.
Use Integrated Pest Management (IPM) for successful plant problem 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.
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
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.
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.