Aspen's Douglas-Fir Bark Beetles

This Spring, Aspen Fire is working with with local partners  (City of Aspen, Pitkin County, Aspen Skiing Company, Colorado State Forest Service, ACES, and USFS) to address the spread of bark beetles on the face of Aspen Mountain. Due to ongoing drought conditions, Douglas-fir beetle populations are likely to increase and detrimentally impact our forests near town.

Why Is Aspen Fire Involved?

Because wildfires behave differently in beetle-killed forests.

Fires in beetle-killed areas are typically more severe, difficult to revegetate, and can experience high erosion. Red trees have greater fire risk than bare trees. In roughly 10 years, 80% of beetle-killed trees will fall and fire risk becomes extreme, especially during specific weather conditions.

The map (below, left) is AFPD's wildfire risk map. This tool factors in vegetation, topography, neighboring land features, and many other elements to inform wildfire risk reduction. Notice that areas of "Very High" wildfire risk overlap with proposed beetle treatment zones (below, right). By preventing additional beetle kill, we are helping keep our local forests green and resilient while reducing hazardous future fuels buildup adjacent to town.

The Science

Mitigation Strategy

Forested areas dominated by Douglas-fir trees around the City of Aspen area will be treated beginning in May 2022  with MCH pheromone pouches of repellent that will be attached to trees. The pouches repel bark beetles by mimicking communications, signaling to incoming beetles that the trees within the treatment area have already been attacked. The beetles, sensing the trees are already infested, move on rather than attacking the treated trees. Studies have shown that MCH packets have a 90% efficacy rate.

Treatments are planned for several years, as drought conditions continue, until beetle populations are reduced and tree defenses have rebounded.

For More Information please contact David Coon, City Forester: david.coon@aspen.gov