Douglas Fir Tussock Moth (DFTM)

Doug Fir Tussock Moth - caterpillar

What It Is

The DFTM is a native insect that experiences outbreaks every 7 to 10 years. Usually the outbreaks last about three years. Trees will sometimes survive a single defoliation but may not survive repeated attacks. 


Normally DFTM is kept in check by native predators and pathogens. During outbreak situations landowners may chose to treat high value trees when the DFTM caterpillars first emerge, usually in early May.

2015 Outbreak

In 2015, Jefferson County experienced an outbreak of DFTM in the southern portion of the county.

The U.S. Department of Agriculture Forest Service (USFS) and Colorado State Forest Service (CSFS) monitored the outbreak. Because the federally threatened Pawnee Montane Skipper is known in the area of Jefferson County that was experiencing DFTM activity, treatment choices were limited.