Douglas-fir Tussock Moth in the Pacific Northwest

photo of a mature DFTM larvaDouglas-fir tussock moth (DFTM, Orgyia pseudotsugata) is a native insect that feeds on the needles of Douglas-fir and several true firs throughout the western US and Canada. Heavy defoliation may lead to tree mortality, and hairs from the DFTM caterpillars cause allergic reactions for some people. View additional information about DFTM biology, effects on treesmanagement options, or recent suppression projects in OR and WA.


 DFTM populations typically increase in the Pacific Northwest every 9-11 years, sometimes causing defoliation that is detectable during aerial detection surveys.  Even during DFTM outbreaks, visible defoliation is often only found in localized areas. After ~3-4 years, outbreaks usually collapse due to the effects of natural enemies, that include a virus, parasites, and predators and/or larval starvation. An Early Warning System has been in place since 1979 to alert forest managers to changes in local Douglas-fir tussock moth populations. Each year, pheromone traps are placed on forest lands in many western states as a cooperative effort among state forestry agencies and the USDA Forest Service.  For the Pacific Northwest, products from this Early Warning System include maps, trend charts, reports, a spreadsheet, and a database.


 In Oregon and Washington, this trapping program is a cooperative effort by Oregon Department of Forestry, Washington Department of Natural Resources, and the USDA Forest Service Pacific Northwest Region.


Links to Other DFTM webpages:

   DFTM home (overview) Early Warning System (overview)
       biology      maps
       effects      trends
       management      reports
       recent suppression projects      spreadsheet



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