WSU Extension

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Caption: Douglas-fir tussock moth
Photo by: R.D. Akre
  
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Spruce : Douglas fir tussock moth
(revision date: 1/27/2016)


Biology
Douglas fir tussock moth larvae are distinguished by three long tufts of black hairs on their body (two in front, one in back) and lighter tufts along their back. They feed on the needles of spruce, Douglas fir, and true firs. On trees grown in the open, the larvae start at the top and work down, feeding mainly on the new foliage. Tussock moth outbreaks are sporadic. The hairs from tussock moth caterpillars break off easily and may irritate the skin.
Management Options

Non-Chemical Management
  • Parasites and other natural controls keep this pest in check most of the time.
  • Do not touch caterpillars with bare hands. Use gloves to handpick caterpillars.
Select non-chemical management options as your first choice!

Chemical Management


Monitor trees and apply when caterpillars first appear. Horticultural oils, soap-based products and some other products may cause discoloration of spruce needles, particularly on Colorado blue spruce. Read labels carefully and test on a small area before application. 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 Systemic Insect Control
    Active ingredient: acephate  |  EPA reg no: 239-2461-4
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Safer Brand Caterpillar Killer for Trees, Shrubs & Vegetables Conc II [Organic]
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 70051-106-42697
  • Safer Brand Caterpillar Killer/Trees, Shrubs, & Vegetables Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 42697-23
  • This list may not include all products registered for this use.
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Caption: Douglas-fir tussock moth
Photo by: R.D. Akre