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Mountain Pine Beetle (MPB)

Mountain Pine Beetle (MPB) is a commonly known destructive beetle native to the western portion of North America.  Although outbreaks typically start in stressed, diseased or damaged trees; however, once an outbreak has been established, MPB will also infest healthy trees.  Mountain Pine beetles are considered the most important pest involving pine trees in Colorado.  Control of MPB is difficult with short term control including sprays, covering infested trees and controlled burns.  Preventative sprays are also available in an attempt to stop infestations from spreading to otherwise healthy trees.  Long term control often includes thinning of susceptible stands of trees in order to leave well-spaced, healthy trees.  This is obviously not a remedy that is likely to be utilized in forest areas due to both financial expense and labor/time involved.

Trees experiencing symptoms of mountain pine beetles attack may include:

1. Pitch-tubes which are popcorn-shaped masses of resin on the trunk of the tree where the beetle begins tunneling.

2. Saw dust like material in the crevices of the bark and at the base of the tree.  This is caused by the beetles boring tunnels into the tree.

3. Wood peckers drilling holes on the tree to feed may also be an indicator of MPB.

4. Blue staining of the sap wood layer of the tree is an indicator of the fungus commonly found in MPB infested trees.  Several areas of the tree should be inspected to confirm activity.

5. Discoloration of foliage often does not begin to occur until 8 to 10 months after the initial attack.  Yellowish to reddish discoloration may spread through the entire crown of the tree as the infestation progresses.

Mountain Pine Beetles are similar in both size and appearance to Ips Beetles; however, the Ips Beetles have the distinctly roughened appearance to their rear ends of their wing covers.

For additional information on mountain pine beetles we recommend contacting your county extension office or an arborist for a consultation.