Contarinia spp.

Photo courtesy of USDA Forest Service Archive, USDA Forest Service,

Signs & Symptoms

Photo by Tracy Olsen, Pennsylvania Dept. Agriculture (PDA).

  • Swollen, yellow needles where maggots are active
  • After emergence of maggots, needles with possible reddish-brown appearance
  • Premature needle loss

Where to Look

Photo by Chal Landgren, OSU.

  • Sites with native Douglas-fir trees nearby

Similar Symptoms As

Photo by Tracy Olsen, Pennsylvania Dept. Agriculture (PDA).

  • Rhabdocline needle cast
  • Cooley spruce gall adelgid


  • By April, place emergence traps under the north side of previously infested trees.
  • Place several traps per field; check frequently to detect and count the midges.
  • Monitor for adult female midge emergence to effectively time spray applications.
  • Check degree-day emergence models online.

Management Options

  • Encourage and protect natural predators.
  • Remove heavily infested trees before larvae exit the needles in the fall.
  • Base insecticide application on collection of adults in emergence traps or field scouting. Insecticides will be effective only against adults.
  • Make first application as traps or weather dictate; often at bud swell to bud break.

Host Susceptibility

host susceptibility graph

  • High susceptibility: Douglas-fir

Management Calendar

  • Look for swollen, yellow needles: June through December
  • Place emergence traps: Mid-March through Mid-May
  • Apply spray control measures based on monitoring: Mid-April through Mid-June
  • Remove infested trees: August through Mid-October