Serving the Foothills & Mountains West of Denver
pine beetle attack

Signs and Symptoms of Mountain Pine Beetle Attack

  • Pitch Tubes - see right
  • Boring dust in bark crevices and on the ground immediately adjacent to the tree base.
  • Evidence of woodpecker feeding on trunk. Patches of bark are removed and bark flakes lie on ground or snow below tree.
  • Foliage turning yellowish to reddish throughout the entire tree crown. Usually occurs either to ten months after a successful pine beetle attack.
  • Presence of live beetles (eggs, larvae, pupae, and/or adults) as well as galleries under the bark. This is the most certain indicator of infestation. A hatchet for removal of bark is needed to check trees correctly.
  • Blue stained sapwood. Check at more than one point around the tree's circumference.

Infested Trees

  • Once mountain pine beetle infest a tree, nothing practical can be done to save that particular tree.
  • Under epidemic or outbreak conditions, enough beetles can emerge from an infested tree to kill about two same-sized trees the following year.
  • Ips and related beetles that emerge early in summer often are mistaken for mountain pine beetle, leading to early reports that "mountain pine beetle is flying." Be sure to properly identify the beetles you find associated with your trees.
  • Trees from which mountain pine beetle have already emerged (look for numerous round, pitch-free exit holes in bark) do not need to be treated.
  • The direction and spread rate of a beetle infestation is impossible to predict. However, attacked trees usually are adjacent or near previously killed trees.

pitch tubes

Pitch Tubes

Popcorn-shaped masses of resin on the trunk where beetle tunneling begins. Pitch tubes may be brown, pink or white in color.