Mountain Pine Beetles

The mountain pine beetle is a naturally occurring bark beetle whose history can be traced into the 1800s. Bark beetles tend to be specific to certain types of trees; the pine beetle is specific to Lodgepole pine and Ponderosa pine trees. Other bark beetles active in Cordillera include the spruce beetle and the fir beetle. Beetle activity tends to move in cycles where the populations grow and shrink. Around 2000 in Canada, beetle activity exploded into an epidemic which moved south, reaching Cordillera around 2004 and peaking in 2009 and 2010. Since 2010, beetle activity in Cordillera had subsided and in 2013 it appeared to be at pre-epidemic levels. However, even at nonepidemic levels, beetles continue to inhabit and kill trees within Cordillera. Property owners are encouraged to spray healthy Lodgepole pine trees or use pheromones to prevent future beetle activity.

In the summer, around the end of June or early July, beetles leave the trees they have inhabited all winter by drilling out of the tree, leaving numerous round holes in the bark. They fly out of the tree only to seek another tree to inhabit, drilling into new trees and creating tunnels to lay eggs. These eggs hatch into larvae in the fall. Beetle activity often kills the tree because the burrowing under the bark interrupts the flow of moisture and nutrients for the tree. Beetles also carry a blue fungus that, once inside the tree, also interrupts the flow of nutrients.

Protecting Healthy Trees

There are 2 steps that property owners should take to protect healthy trees:
  1. Healthy trees should be sprayed with a repellent in the spring, before the beetles fly. Cost per tree to spray is around $10. Cordillera has been using permethrin as the active ingredient of the spray; it is considered the least toxic of all the approved chemicals for pine beetle. At current levels of beetle activity the repellent is very effective.
  2. Beetle infested trees (that often die anyway) should be cut and removed from the property. Removing infested trees also removes the beetles inside and prevents them to attack new, healthy trees.

Cordillera Open Space

The Cordillera Property Owner Association (CPOA) and the Cordillera Metro District (CMD) have been addressing pine beetle issues in community open space. Special attention has been paid to areas adjacent to private property where Cordillera continues to spray healthy trees and remove infested trees.

Several large areas of open space, of thousands of Lodgepole pine, were heavily impacted by the mountain pine beetle. At the peak of the epidemic, trees were dying faster than they could be cut. In these areas, it was unrealistic for the CMD and the CPOA to spray individual trees, nor would it have been environmentally friendly. It was also unrealistic to have a meaningful impact on the epidemic by cutting individual trees; hence clear-cutting large swaths of trees was done, saving the community thousands of dollars and knocking down the epidemic in Cordillera.

Lodgepole Pine Regeneration

In 2006, Cordillera conducted the first clear cuts. Experts advised that natural re-vegetation would be noticeable in about five years. In some locations, Cordillera planted hundreds of Lodgepole saplings. Today, staff estimate that the survival rate of the planted saplings is around 25% and the number of those saplings that are actually flourishing is much less. More importantly, as predicted by experts, natural vegetation has started and is much more prolific then the trees planted by hand.


Aspen is another common species of tree in Cordillera. Aspen are interesting as they grow from roots that spread from other aspen trees and new trees are considered clones. In the fall you may notice that large groups of aspen turn gold at the same time, while others are still green. This is because the leaves of all of the trees in a clone turn at one time.

Aspen trees in Colorado are also experiencing a high level of mortality. There is not one definitive cause for this decline. Experts cite several contributing factors, including several summers of drought, rising temperatures, old age and disease. This has been labeled Sudden Aspen Decline, or SAD. When a stand of aspen begins to experience health issues, the entire stand may become affected. What is alarming about SAD is that some aspen stands that are dying show no signs of regeneration or new growth. There is no treatment for SAD.

Tree Removal

Cordillera supports mitigation efforts for wildfire and mountain pine beetle. Property owners are encouraged to contact Mr. Bill Wentworth to report their efforts. Removal of tree and vegetation that is not related to wildfire or forest health must be approved by the Design Review Board.

Please contact Public Safety by phone at 970-569-6261. Please email Bill Wentworth or call him at 970-306-3632 for more information.