(WOODLAND PARK, Colo.) — The Colorado State Forest Service (CSFS) is warning landowners to be aware of mountain pine beetle (MPB) infestations.

During the summer MPB will migrate to new trees and by October the evidence shows which trees are playing host. The CSFS says to look for the following:

  • Pitch tubes: These look like popcorn, but they’re actually globs of sap. Sometimes healthy trees can flush beetles out with their sap, but if you see multiple pitch tubes or tubes that are red or pink, there’s a good chance that the beetles have successfully infested the tree.
  • Frass: Look around the base of the tree and in crevices in the bark. If you see sawdust, it means that the beetles have been boring into the tree’s bark.

The CSFS recommends looking near trees that were previously attacked which can be spotted from “their dead, orange crowns.”

  • On the left, a ponderosa pine with pitch tubes from MPB infestation, and on the right, a close-up of the pitch tubes.
  • A ponderosa pine with pitch tubes from a mountain pine beetle infestation
  • A close-up of the pitch tubes

According to the CSFS, the only treatment after a tree has been infested is to remove it prior to the following spring. Hauling away or chipping the tree are both options but the tree should be taken at least a mile away from healthy trees.

A Colorado native, the mountain pine beetle (Dendroctonus ponderosae) can naturally thin out the forests. They kill weak and sick trees which makes room for new trees and organisms and feeds the current ones. A forest that is already stressed out from severe conditions like drought or wildfires cannot safely handle a MPB infestation.

The CSFS says, “Healthy, well managed forests are more resistant to MPB outbreaks.”