Prociphilus spp.

Alternate host: Ash tree (Fraxinus spp.)

Photo by Chal Landgren, OSU.

Signs & Symptoms

Photo by Chal Landgren, OSU.

  • General decline of trees and eventual death of the leader and branch tips
  • Typically on 3- to 4-year-old trees
  • Stunted young trees
  • Ant activity around trunks and roots
  • Clusters of white aphids on the roots

Where to Look

Photo by Chal Landgren, OSU.

  • Localized areas in the field

Similar Symptoms As

Photo by Chal Landgren, OSU.

  • Nutrient deficiencies
  • Root problems


  • Scout for ants around the trunks and roots. (Prociphilus spp. feed directly on conifer roots and often are attended by ants. Ants may defend the aphid from natural enemies and move aphids around.)
  • Dig trees and search for root aphids.

Management Options

  • Keep trees healthy and free of pests, disease, and cultural problems.
  • Obtain seedlings from nurseries that have no root aphids.
  • Use available systemic insecticides.

Host Susceptibility

host susceptibility graph

  • High susceptibility: Fraser fir, Noble fir
  • Medium susceptibility: Grand fir, Douglas-fir
  • Low susceptibility: Nordmann fir, Turkish fir

Management Calendar

  • Look for trees declining; drastic growth reduction: All year round
  • Look for ants around trunks and roots: Mid-April through July
  • Spray insecticide (if needed): May through June