Bark beetles killing more trees along the front range, according to a Colorado State Forest Services report

FORT COLLINS, Colo. — The latest findings about the health of Colorado’s forests are a “mixed bag”, according to forestry experts.

On Tuesday, the Colorado State Forest Service released its annual report tracking the damage from forest pests.

“Insects are so closely tied to a lot of that temperature and precipitation so in Colorado it’s really been a number of years, actually 31 years, since we’ve been below average temperatures so that makes it really hard to be a tree in Colorado,” CSFS forest entomologist Dr. Dan West said.

West uses an airplane each summer to fly over all 24 million acres of forested land in Colorado. He visually inspects each acre to pinpoint problem spots where bark beetles may be moving in and killing trees.

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“When we’re flying over some areas and you don’t expect to see anything and you do, it really is alarming,” West said.

According to the report, the front range is experiencing a surge in activity from the mountain pine beetle. In 2021, the insect impacted 1,500 acres statewide. In 2024, that number grew to 5,600 affected acres and included areas in Jefferson County and Castle Rock.

“That’s kind of a big deal along the front range as more and more people are moving to our front range and living in our wildland-urban interface. it really affects every one of us,” West said.

Not only do the dead trees cause forests to be less visually attractive, but they also create more fuel for more damaging wildfires.

“What it does is it changes the fuel arrangement of the trees and the forests that we see,” West said. “It takes those needles and puts them on the forest floor so should a fire start, it has the ability to burn hotter and the effects of that fire can certainly be greater.”

According to the report, a cool and wet 2023, followed by a hot and dry 2024, exacerbated the bark beetle problem.

“Four out of the last five years have been below average precipitation, and so trees take that precipitation and turn it into resin. That resin then helps defend against a lot of these forest pests,” West said.

Without as much resin protection, trees are unable to protect themselves against pests.

The western spruce budworm is having the most widespread impact on Colorado’s forests. In 2024, West and his team observed 207,000 affected acres compared to 91,500 acres in 2021.

“As these bark beetles continue to build populations, they affect and kill more trees. We really start to see the effect on our everyday lives. not just with the air we breathe and the water we turn on but the places that we love to recreate,” West said.

The report does contain some positive news. Spruce beetle populations have decreased dramatically over the past four years. In 2021, they were active across 53,400 acres. In 2024, that number dropped to 11,000.

“Beetle populations within and near Rocky Mountain National Park continue to decline as available uninfested trees are depleted,” the report said.

Bark beetle infestations are not new to Colorado. The state has seen ebbs and flows of destruction in the past several decades. The last few years have been considered a lull in activity.

“Comparatively, thinking about in history, we’re much lower on some of these pests than we’ve ever seen and although the numbers can be staggering, when we put it into perspective we had many many more acres affected of western spruce budworm in the 1980’s than we’re seeing currently,” West said.

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According to West, the data he collects each summer helps guide forest managers in mitigating the impact pests have on the forest and the people who enjoy it.

“We have some tools in our toolbox. it’s not just doom and gloom,” he said.

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