WSU Extension

Hortsense

Caption: Arborvitae cypress tip moth damage
Photo by: R.S. Byther
  
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Arborvitae : Leafminers
(revision date: 3/8/2016)


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

Non-Chemical Management
  • 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.
Select non-chemical management options as your first choice!

Chemical Management


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.
  • Bonide Captain Jack's Deadbug Brew RTSpray [Organic]
    Active ingredient: spinosad  |  EPA reg no: 4-471
  • Bonide Systemic Insect Control
    Active ingredient: acephate  |  EPA reg no: 239-2461-4
  • GardenTech Worry-Free R-T-U
    Active ingredient: pyrethrins, piperonyl butoxide  |  EPA reg no: 1021-1801-71004
  • This list may not include all products registered for this use.
Images
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Caption: Arborvitae cypress tip moth damage
Photo by: R.S. Byther
Caption: Arborvitae cypress tip moth damage
Photo by: A.L. Antonelli
Caption: Juniper cypress tip moth
Photo by: A.L. Antonelli