Seeley Swan Pathfinder -

By Andi Bourne

Douglas-fir Tussock moth outbreak damaging trees – causing allergic reactions


August 8, 2019

USDA, Forest Service

A Douglas-fir tussock moth caterpillar. There have been many reports of finding these while picking huckleberries around Seeley Lake and in the Swan. If handled, they can cause an allergic reaction, in some cases creating severe irritation.

Douglas-fir trees throughout western Montana are being damaged by an outbreak of Douglas-fir tussock moth (DFTM). It is localized to the historic outbreak regions including Missoula. Caterpillars and the egg masses of the Douglas-fir tussock moth can cause "tussockosis."

 The Montana Department of Natural Resources and the USDA Forest Service are currently monitoring the scope and extent of damage. For the previous one to two years, DFTM have damaged the tops of ornamental Colorado blue spruce, which is typical prior to noticeable damage in Douglas-fir forests. 

DFTM are voracious feeders...

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