You might remember how Colorado’s most significant mountain pine beetle outbreak—from the late 1990s through 2013—reshaped forests across the state. While these insects are native to Colorado and play a natural role in forest ecosystems, periodic outbreaks can kill large numbers of trees, particularly in dense or drought-stressed forests. This year, Douglas County is preparing for increased mountain pine beetle activity in Ponderosa pine forests along the Front Range.
What can you do?
First, keep reading to be informed of how mountain pine beetles behave during different seasons and steps you may need to take to reduce wildfire risk this year.
About Mountain Pine Beetles in Douglas County
Mountain pine beetles attack pine trees by burrowing under the bark, disrupting the tree’s ability to transport water and nutrients, often killing the tree within a year.
In Douglas County, risk is expected to be greatest in western areas near Roxborough and adjacent national forest lands, where conditions are more favorable for infestation. While Ponderosa and Lodgepole pines are most susceptible, nearly all pine species can be affected.
“Pine beetle outbreaks are cyclical and expected, but how we respond depends on the stage of the beetle’s life cycle,” said Mike Alexander, Office of Emergency Management Director. “This summer, residents should focus on identifying infested trees. If a tree begins turning yellow and then red, it is likely dying from a beetle attack. While it may be tempting to remove it immediately, transporting an infested tree while beetles are still active can spread the infestation to new areas.”
What to Look For
Douglas County residents are encouraged to routinely check pine trees on their property for early signs of infestation, including:
- Popcorn-like pitch tubes (white, pink, or brown) on the trunk
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Fine sawdust (boring dust) around the base of the tree in late summer and fall
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Increased woodpecker activity or bark flaking
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Needles turning yellow in summer, then red towards fall
It is important to note that once a tree begins to yellow and die over the summer, it must be removed, eventually. There is nothing residents can do to save the tree at that point.
Why Timing Matters
Mountain pine beetles spend most of the summer developing beneath the bark of infested trees. Moving infested wood before the beetles become dormant can unintentionally spread them to healthy forests and neighborhoods.
It’s summer, so mountain pine beetles are now flying and actively attacking pine trees, meaning the trees they previously infested will begin to slowly die.
Residents are encouraged to monitor and mark infested trees during the summer and plan for removal after beetle activity has subsided to avoid spreading the beetle infestation by hauling infected trees.
By September, when beetles begin entering dormancy, most infested trees can be safely removed and properly disposed of.
Removing Dead Trees Supports Wildfire Resilience
While infested trees should remain in place during the active beetle season, removing dead trees once beetles are dormant helps reduce hazardous fuels, improve defensible space around homes and help reduce the pine beetle population next year.
Forestry experts emphasize that overcrowded and stressed trees are most vulnerable to attack, making ongoing forest management one of the most effective prevention strategies. Residents can help improve forest health by:
- Removing trees already stressed by insects, disease, or drought
- Thinning dense stands of trees to reduce competition
- Maintaining tree health through proper watering and care
- Removing dead trees when it is safe and appropriate to do so
Plan for Fall and Winter
Beginning this fall and winter, residents can work with qualified arborists to apply preventive treatments to uninfested trees before the next flight season. These treatments can help protect healthy trees from future attacks, but are not effective once a tree has already been successfully infested.
Douglas County is working closely with the Colorado State Forest Service and regional partners to provide consistent, science-based guidance to help residents protect their forests, homes, and communities.
Learn more about how to identify and manage pine beetles by visiting Douglas County’s Mountain Pine Beetle resource page: Learn more about pine beetle prevention and wildfire preparedness