Cooley Spruce Gall Adelgid

Colorado spruce, white spruce, Norway spruce, Douglas fir

What you will see:

  • Large brown pineapple–like structures at end of twigs
  • Large green pineapple-like structures at end of twigs
  • Small cotton ball-like egg masses

Life cycle:

  • Overwinters as females attached to the current year’s twigs at the bases of buds
  • Females mature and lay 150 to 200 olive-green eggs Eggs hatch into yellow nymphs
  • Nymphs move to needle bases to feed and form galls
  • Nymphs molt three times in the gall and emerge in August and September
  • Mature nymphs crawl to needles and molt into winged females
  • Nymphs lay a second generation of eggs (up to 60) then die
  • These eggs hatch into the overwintering females

Cultural practices:

  • Remove and destroy green galls
  • This technique is only effective where the trees have few galls
  • Plant less susceptible trees (true firs)
  • Effective chemical treatments include systemic and foliar insecticides. Follow your Consulting Arborist’s recommendations.
  • An integrated approach
  • When caring for urban trees it is important to make a complete evaluation of all environmental conditions to accurately diagnose all stress factors and prescribe care based on specific circumstances. This prescriptive care will help your tree meet its full potential.