Vast swaths of the ponderosa pine forests that blanket Colorado’s Front Range mountains could turn rust-colored and die over the next five years as pine beetles begin to spread aggressively, new federal forecasts show. Aerial surveys conducted by the U.S. Forest Service over the last year found ev idence of rapidly spreading beetle infestations along the mountains and foothills that stretch from southern Larimer County to southern El Paso County, including the western flank of metro Denver. Already, pockets of dead trees are visible from Interstate 70 and U.S. 285. The rapid uptick in beetle-killed trees near the state’s largest cities and major highways prompted state leaders to form a task force this month to grapple with the outbreak. Gov. Jared Polis issued an executive order Dec. 15 and created the Mountain Pine Beetle Ponderosa Outbreak Task Force to address the growing wildfire threat and the beetles’ potential impact to watersheds, recreation and infrastructure. “We’ve been through several cycles of outbreaks. But what’s new here is the start of a massive outbreak in the western Front Range, very close to our population centers … where projections show that over the next several years, there will be near-100% fatality for ponderosa pines,” Polis said in an interview. A forecast map released by the governor’s office shows that beetles could kill nearly all of the ponderosa pines along the Front Range. The map, produced by the U.S. Forest Service, shows how experts predict the beetles will spread through the forests unless a major weather event, like flooding or an extended extreme freeze, slows their expansion. The impacted area extends from near Jamestown, northwest of Boulder, to the forests south of Pikes Peak. It also includes areas east of Lake Granby and along the I-70 corridor between the western edge of Denver and Georgetown. Pine beetles have ravaged forests in Colorado’s mountains for three decades now. There’s little to be done to stop the beetles from spreading, Colorado State Forester Matt McCombs said. “There are ways to mitigate the impacts,” McCombs said. “But our ability to stop the spread is very limited.” How pine beetles work Pine beetles are native to Colorado and help thin out diseased and dying pine trees, creating more space for younger, healthier trees to thrive. But continuous warmer temperatures and drought — conditions made more likely by climate change — have sapped otherwise healthy trees’ defenses to the beetles. A dead pine tree showing signs of pine beetle infestation stands off Interstate 70 near Black Gore Creek on Thursday, Dec. 18, 2025, near Vail. (Photo by Timothy Hurst/The Denver Post) Dry and stressed trees produce less resin, which is the natural defense to beetles. A lack of extreme cold periods in spring or fall has also allowed pine beetles to continue to spread. If Colorado experiences a relatively warm and dry winter followed by a warm, dry spring, the beetles will expand rapidly, McCombs said. The small black beetles are also able to spread quickly in dense forests with trees that are relatively the same age, McCombs said. Forests become unhealthy and homogenous when wildfires are suppressed and people do not actively manage the woods, he said.  Outbreaks are less likely in forests with a variety of tree species of different ages, according to the Forest Service. “Right now, because the trees are all the same age and are in close proximity, it’s sort of a ready-made buffet for the mountain pine beetle,” he said. In the summer, mountain pine beetles emerge from the now-dead tree in which they were born and seek a new tree nearby to procreate and lay eggs. The larvae spend the winter and spring under the bark by feeding on the tree and fungus, before coming to the surface in the summer and seeking a new tree to bore into. The beetles can fly more than a quarter-mile in search of a new host tree. One infected tree can produce enough beetles to spread to up to 10 new trees, McCombs said. The needles on an infested pine tree turn to a rust color within a year, though sometimes the color changes within weeks. The needles then fall from the branches and the tree dies, turns grey and eventually falls down. The dry needles and dead trees can serve as ready fuel for fire. Once pine beetles infect a tree, nothing can be done to save it. “People are rightfully alarmed — and my hope is that we can translate that alarm into action,” McCombs said. A map produced by the U.S. Forest Service shows current and recent pine beetle infestations along Colorado's Front Range and nearby ranges (shaded blue) and the expected spread of the beetles by 2030 (shaded yellow, orange and red). (Courtesy U.S. Forest Service) Reducing impacts Along with the formation of the task force, Polis will include a list of recommended actions in his budget request to the state legislature, which is scheduled to convene Jan. 14. The recommendations will include wildfire risk-management strategies, assistance to help landowners pay for wildfire and beetle mitigation, an expansion in the use of beetle-killed timber and funding for research on beetles. “The increased fire risk and tree mortality, combined with the high population and infrastructure density on the Front Range, is not just a concern for forest health — it is a public safety, water quality, recreation and economic issue,” Polis’ executive order states. Colorado’s forests have experienced pine beetle outbreaks for years, but the Front Range remained mostly unscathed. An outbreak of beetles that began in the late 1990s has impacted 3.4 million acres of forests, primarily lodgepole pines in Summit, Grand, Eagle and Routt counties. The beetles killed up to 90% of trees in some of those areas. Pine beetles began to attack ponderosa pines along the Front Range in the early 2010s, but heavy rains and flooding stopped their spread. The presence of beetle-killed trees intensified the two largest wildfires in state history, the Cameron Peak and East Troublesome fires of 2020, according to the Colorado State Forest Service. Beetle-killed trees make fires more complex and more intense, and they increase the rate of spread, said Mike Morgan, the director of the Colorado Division of Fire Prevention and Control. The state has made significant investments in its firefighting staff and equipment in the years since the 2020 fires, he said. “We know we can’t change the fact that we’re going to have a lot of beetle-kill trees, but we can reduce impacts from that by working together,” Morgan said. Piles of pine tree logs that were felled and covered in plastic are seen in the Idaho Springs Cemetery on Thursday, Dec. 18, 2025, in Idaho Springs. The logs showed signs of beetle infestation. (Photo by Timothy Hurst/The Denver Post) Related Articles Colorado looks to logging to help re-balance forests in an era of climate-triggered megafires Southwest Colorado forests under attack by pine beetle Colorado’s snow season is having an abnormally warm and dry start — boding poorly for snowpack Dead trees are more unstable and pose greater risks for people hiking, biking and camping in Colorado’s forests, said Dan Gibbs, the executive director of the Colorado Department of Natural Resources. Fallen trees and disturbed roots can also create less-stable slopes that are more prone to sliding and erosion. The new task force will convene leaders from state and federal agencies, utilities, tourism groups, insurance and timber companies, housing organizations and conservation experts. The Polis administration plans to appoint members of the task force by Feb. 1. While there’s little to be done at scale to prevent the spread from the current outbreak, McCombs expressed hope that the task force’s work would better prepare Colorado for beetle infestations and promote better forest management. “The opportunity is for us to think about how to protect communities, our forests, our water supply — that’s going to be a key focus,” he said. “But I hope, concurrently, that we can think about this idea and promise ourselves that we’ll never get in this pickle again. We have a responsibility as Coloradans to better manage our forests.” How to recognize a pine beetle infestation These symptoms are indicators of pine beetle infestations: ► 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. ► 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. For more information about beetle management options and wildfire mitigation visit: csfs.colostate.edu/live-wildfire-ready. Source: Colorado State Forest Service. Get more Colorado news by signing up for our Mile High Roundup email newsletter. ...read more read less