In Pine Brook Hills, Beetle Season Is a Winter Job

When did you last look closely at the bark on your ponderosas? The flight was over by mid-September. Every tree this year's mountain pine beetles were going to attack has already been attacked, and in each of those trees the next generation is now developing quietly under the bark. Nothing in the canopy looks different in November. The months when a homeowner can change what happens next summer have started anyway.

The Summer 2026 issue of the Pine Brook Press opened with this subject. HOA president David Downing passed along a warning from local arborists that the Front Range has more than twice as many mountain pine beetles as it did the summer before. That figure is the arborists' estimate, not an official count. The official numbers point the same way, and the calendar behind them explains why winter is when this gets decided.

The beetles are already inside

The Colorado State Forest Service describes the mountain pine beetle's year as one cycle in three stages:

1. July to mid-September. Adults fly and attack new trees.
2. September to December. Eggs hatch, and larvae begin developing under the bark.
3. January to June. Larvae finish developing, then pupate in late May and June before the next flight.

So a tree that was hit in August is carrying the next brood right now. CSFS's management guidance is plain about the timing. Inspect pines in the fall, after the adults have flown, and remove infested trees by the following spring, disposing of the wood properly so the beetles can't spread. The agency also says an infested tree can't be saved. Removing it is meant to protect the trees around it, not the tree itself.

That turns November through May into a deadline more than an off-season. Whatever is still standing and infested when the flight starts in July becomes next year's source.

The regional count, and why it runs low

CSFS's aerial survey mapped 5,544 acres of beetle-affected ponderosa forest across nine Front Range counties in 2025. In 2024 it mapped 2,236 acres, so the total rose 148% in a year. Boulder County accounted for 601 mapped outbreak acres in that analysis, or about 171 acres once adjusted for severity. CSFS cautions that these are survey estimates, not a tree-by-tree census.

Two details shape how to read those numbers. First, CSFS's May 2026 outlook calls the outbreak localized and not yet epidemic, while warning that it is increasingly visible and could expand. Second, the 2025 survey covered about 13.4 million Colorado forest acres. In 2024 it covered nearly 30 million, and CSFS says the reduced coverage likely understates impacts statewide. Closer to home, Boulder Reporting Lab reported in February that Boulder County has seen increased beetle activity in several areas, including upper Lefthand Canyon and Jamestown.

The trend is up, and the official counts likely run low. What happens on any single hillside comes down to individual trees and the people who own them.

Fifty properties out of four hundred

Pine Brook Hills already organizes around this. Each spring when beetle pressure rises, the HOA recruits and trains volunteer tree inspectors. This spring seven Beetle Buster teams inspected more than 50 properties and tagged dozens of pines for removal. Their trainer is Jim Adams, a self-taught arborist the newsletter calls an all-around Local Hero. Residents could also sign up for a Beetle Buster assessment at the Boulder Mountain Fire Auxiliary's Community Safety Fair on May 30, where the Colorado State Forest Service spoke about protecting the forest from beetles.

The same column does the math. Fifty properties out of about 400 in Pine Brook Hills is one-eighth of the neighborhood. It asks residents to become their own beetle busters, because one dead or dying tree on a property can lead to a handful of dead trees the next year. The newsletter lists the signs to look for:

• Brown, thinning needles on pine branches
• Bore holes in the bark that look like nail holes
• Puffs of white or pink resin that look like popcorn
• Sawdust-like boring dust, called frass, at the base of the tree or caught in the bark
• Recent woodpecker activity

Since this is the season CSFS recommends for inspection, that list is most useful now, with bare ground around the trunks and the summer's activity left in the bark.

The free drop-off closes on Nov. 14

Finding an infested tree is half the job. The other half is the wood, and the free county options are nearly gone for the year.

Boulder County runs two Community Forestry Sort Yards that take logs, branches, and forest litter for free. According to the county's Oct. 16 notice, the Meeker Park yard at 8200 Hwy 7 in Allenspark closed for the season on Saturday, Oct. 31. The Nederland yard at 291 Ridge Road closes at 5 p.m. on Saturday, Nov. 14. Nederland is open Wednesday through Saturday from 9 a.m. to 5 p.m. and closed Wednesday, Nov. 11, for Veterans Day. Counting from Thursday, Nov. 5, that leaves six open days: Nov. 5, 6, 7, 12, 13, and 14.

The sort yards turn away beetle-infested logs and chunk wood only during the July 15 to Sept. 15 flight season. In November they accept them, provided the logs follow the yard's prep rules. Branches must be trimmed flush, ends squared, logs at least 4 inches in diameter, and wood stacked by length. The county lists Wayne Harrington at 303-678-6368 for questions about yard status.

Neighborhood chipping won't help with beetle wood. Boulder County's Wildfire Partners Community Chipping Program chips slash from pruning and thinning at neighborhood events organized by a volunteer host. It specifically excludes tree removal projects and mountain pine beetle-infested wood, which it says needs separate management and disposal.

So a tree tagged in December or February has no free county drop-off waiting for it. The yards' 2026 seasons opened in May, which falls inside CSFS's window but only a few weeks before pupation.

What CSFS lists for wood that stays on the mountain

Through the rest of the winter, the wood from an infested tree is mostly handled where it falls or taken somewhere private. CSFS lists four ways to treat infested material:

• Chipping, which destroys the habitat under the bark
• Debarking the logs
• Solar treatment, which means stacking cut logs off the ground in full sun under clear plastic. CSFS says this takes four to six weeks of hot weather, so it fits late spring better than January.
• Burning, only where it is safe and locally permitted

CSFS also points residents to transfer stations, landfills, and wood drop-off businesses, and recommends confirming each site's rules first. Its firmest instruction is about movement. Don't move infested wood unless you're taking it to a secure location, because moving it can spread the beetles. For a neighborhood of steep driveways and dense ponderosa stands, that rules out a woodpile of infested rounds next to the garage until spring. The brood would just finish developing there.

Thinning is the longer-term option. CSFS calls thinning overly dense stands the most successful forest management strategy for tree vigor, since beetles most often attack stressed trees. The Pine Brook Press makes the local version of the point. Trees growing too close together and trees under drought are the most vulnerable, and the recent mild winters and dry conditions have given beetles an easy target in local ponderosas.

Nov. 14, twice over

Saturday, Nov. 14, is the Nederland yard's last day. It is also the first day of the Boulder Mountain Fire Auxiliary's main annual event, Boulder Mountain Handmade, at the Elks Lodge, 3975 28th St. The market runs Nov. 14 and 15 from 10 a.m. to 4 p.m. It is the Auxiliary's only fundraiser and supports the Boulder Mountain Fire Protection District. Alongside work from Colorado artisans, it has Boulder Mountain Creates, a market-within-the-market for art and crafts by fire district residents, and Boulder Mountain Bakes, the bake sale stocked by district households. Wild Horse Circle residents Jane and Steve Glotzer volunteer with the Auxiliary, and Jane leads the neighborhood craft area and the make-and-take table.

That weekend you could drop off a trailer of squared-off logs in Nederland on Saturday morning and come down the canyon for pie at the Elks Lodge before 4.

I've spent my career helping people see what a property can become, and on a Pine Brook Hills lot the ponderosas are a big part of that, both in how the place feels and in what it's worth. If you're weighing removals or thinning this winter and want to talk through how it changes the look of your land, I'm happy to walk it with you. Kristi Clary is always glad to hear from neighbors in the Pine Brook Hills community. Let's Connect.