Pine beetle infestations are quickly spreading across large areas of Colorado’s ponderosa pine forests, evident from aerial surveys conducted by the U.S. Forest Service over the last year.

The USFS surveys found beetle infestations in mountainous and foothill regions from Larimer County to El Paso County have been on the rise over the last year, suggesting large areas of forests near major Colorado metro areas could look a lot different within the next five to 10 years.

To combat the pine beetle problem, Gov. Jared Polis created a Ponderosa Mountain Pine Beetle Task Force in a Dec. 15 executive order.

“Colorado has long been a leader in forest health and fire mitigation efforts, and this is no exception,” Polis said. “As the latest outbreak of pine beetles begins to take shape along the densely populated Front Range, we are taking an aggressive approach to boost tools and partnerships to help protect our communities, forests and key water sources, and equipping homeowners with the resources they need to better protect their homes.”

The governor will also submit a supplemental request to the state legislature, recommending actions aimed at reducing wildfire risk, supporting landowners and saving them money on risk mitigation investments, and strengthening Colorado’s long-term response to the pine beetle outbreak.

The Polis administration plans to appoint members of the task force by Feb. 1.

Beetle-caused mortality to forests can create public safety hazards, alter fire behavior and make fire suppression more challenging for firefighters, the USFS said.

Pockets of beetle-killed trees are already visible along the major Front Range highways like U.S. Highway 285 and Interstate 70.

According to the USFS, warming climates and drought have created optimal environmental conditions for the beetles to spread into neighboring trees.

Very low temperatures are necessary to diminish the beetles’ progress. The state has recently been experiencing prolonged dry conditions, which weaken the trees’ defenses.

“A very high level of tree mortality, especially among ponderosa pines, is likely to continue for the next decade,” the USFS said.

The Colorado State Forest Service has an online map of Colorado showing where pine beetle infestations have been prevalent and expanding from 2022-2024.

The interactive map shows ponderosa pine forests in portions of Larimer, Gilpin, Clear Creek, Boulder, Jefferson, Park and Douglas counties are experiencing elevated levels of infestation from mountain pine beetles.

In addition, lodgepole pine forests in Park and Gunnison counties that evaded prior bark beetle outbreaks are experiencing elevated mortality of trees as populations of mountain pine beetles expand.

Lastly, ponderosa pine forests on the Uncompahgre Plateau in western Colorado have also been affected by increased pine beetle activity.

A forecast map from the USFS shows that beetles could kill nearly all of the ponderosa pines along the Front Range.

The map shows how foresters predict the beetles’ spread through the forests; however, unless a major weather event like flooding or an extended freeze cycle happens to slow the expansion, the beetles will continue to find new trees and spread across the forested regions.

The mountain pine beetle is native to Colorado and ranks first in destructiveness among the tree-killing bark beetles that are native to the West, according to the U.S Department of the Interior.

Bark beetles infest pine trees by laying eggs under the bark. When the eggs hatch, the larvae mine the area beneath the bark and eventually cut off the tree’s supply of nutrients. The beetles also carry a fungus that causes dehydration and inhibits a tree’s natural defenses against beetle attacks.

From the late 1990s through 2013, mountain pine beetles affected 3.4 million acres of forests in Colorado, predominantly attacking lodgepole pines, according to the Colorado State Forest Service. The beetles killed up to 80-90% of trees in some lodgepole pine forests in Summit, Grand, Eagle and Routt counties during the epidemic.

Pine beetles attacked ponderosa pine forests along the Front Range in the early 2010s, but heavy rains and flooding, like the 2013 floods, stopped their spread.

“This is not a time to panic, it’s a time to ramp up and take action to reduce the impacts of this outbreak and ensure we never allow our forests to become this vulnerable ever again,” Matthew McCombs, state forester and director of the Colorado State Forest Service, said in a news release.

The Colorado State Forest Service said residents should look for these telltale signs and symptoms of mountain pine beetle infestation:

• Popcorn-shaped masses of resin, called pitch tubes, on the trunk that may be brown, pink or white.
• Boring dust in bark crevices and on the ground immediately adjacent to the tree’s base.
• Woodpecker damage, where the birds have stripped portions of the bark in search of larvae, leaving accumulations of bark at the base of the tree.
• Presence of live mountain pine beetles (eggs, larvae, pupae and/or adults)
• Exit holes on the bark’s surface where adult beetles have emerged.
• Foliage turning yellowish to reddish throughout the entire tree crown, which usually occurs eight to 10 months after a successful attack.