Trisetacus spp., Epitrimerus pseudotsuagae, and Nelepella ednae

Photo by Sandy Gardosik, Pennsylvania Dept. of Agriculture (PDA).

Signs & Symptoms

Photo by Robin Rosetta, OSU.

  • Bronzing and stunting of new needles, or bronzing and curling of more developed new shoots
  • Needles later turn brown, die, and drop from the shoot, leaving naked branch tips

Where to Look

Photo by Sandy Gardosik, Pennsylvania Dept. of Agriculture (PDA).

  • Localized areas in the field

Similar Symptoms As

Photo by Chal Landgren, OSU.

  • Damage caused by environmental stress
  • Other mites
  • Chemical and nutrient imbalances


  • Look for needles at the branch tip that appear white-flecked or fuzzy when mite population is high.
  • Check for clear to tan-colored eggs in clusters from late February through March.
  • Check for active mites from late April through summer.

Management Options

  • Begin chemical control measures when new mites emerge (April to May) and again in the fall (October to November).

Host Susceptibility

host susceptibility graph

  • High susceptibility: Noble fir
  • Medium susceptibility: Grand fir, Douglas-fir

Management Calendar

  • Look for new needles bronzing and stunting: March through December
  • Look for eggs: Mid-February through Mid-March
  • Spray miticide (if needed) labeled for eriophyid mites: Mid-March through May, September through Mid-November