Understanding Mountain Pine Beetles in Black Forest

Black Forest is currently experiencing a growing mountain pine beetle outbreak in ponderosa pine forests. Many residents are noticing fading trees, pitch tubes, woodpecker activity, and increasing tree mortality across the area.

One of the biggest challenges during beetle outbreaks is that many people remove the wrong trees at the wrong time. Understanding when trees were attacked, which trees currently contain developing beetles, and how forest structure affects wildfire and ecosystem health is critical to making informed decisions.

This page is intended to help residents understand:

• The mountain pine beetle timeline
• How to identify infested trees
• What should be removed
• What can wait
• Why some dead trees should remain
• How forest health and wildfire mitigation work together

The Beetle Timeline

Mountain pine beetles operate on a multi-year cycle.

A tree that looks dead today was usually attacked the previous year.

That means:

• Trees fading red or orange in 2026 were generally attacked in 2025
• Trees attacked during 2026 may still appear mostly green this summer
• Beetles developing beneath the bark right now are expected to emerge later this year

This timing is important because mitigation efforts are most effective before new beetles emerge and fly to surrounding trees.

Why Timing Matters

The current window for slowing beetle population growth is short.

Before Mid-June

This is the most effective period to:

• Identify recently infested trees
• Remove infested trunkwood
• Dispose of infested material before beetle flight intensifies

After Mid-June

Mountain pine beetle flight activity is expected to increase significantly.

Once flight season intensifies:

• Transporting infested wood is generally discouraged
• Freshly cut pine can attract additional beetles because of sap and pitch odors
• Certain cutting activities may unintentionally worsen spread

At that point, infested wood may need to be:

• Chipped
• Ground
• Buried onsite
• Otherwise contained locally

Mountain pine beetle management is seasonal, and strategies that are appropriate in winter or spring may not be appropriate during summer flight season.

Understanding the Maps

Each year, the USDA Forest Service and Colorado State Forest Service conduct aerial detection surveys across Colorado forests.

These surveys identify:

• Fading trees
• Areas of mortality
• Expanding beetle infestations

The maps are extremely useful for understanding regional outbreak patterns, but they can also be misunderstood.

Aerial surveys typically detect trees that are already fading from attacks that occurred during the previous year.

For example:

• Trees mapped as “faders” in 2025 were usually attacked in 2024
• Newly infested green trees may not yet appear on the maps

This means ground-level inspections are still critical for identifying currently infested trees.

Identification

What Trees Should Be Removed Right Now?

The highest priority trees are generally:

• Trees still green but already infested
• Trees beginning to fade or wilt
• Trees with hard brown pitch tubes
• Trees with blue-stained wood beneath the bark

These trees may still contain developing beetles preparing to emerge later this season.

The goal is to interrupt the next generation before flight begins.

Pitch Tubes

Pitch tubes are one of the clearest signs of mountain pine beetle activity.

Hard Brown Pitch Tubes

Hard, dried pitch tubes usually indicate older attacks where beetles are already developing beneath the bark.

These trees are often priority candidates for removal before flight season.

Fresh Pink or Sticky Pitch Tubes

Fresh pink, cream-colored, or gooey pitch tubes may indicate a very recent attack.

Some of these trees may survive. Others may become next year’s fading trees.

At this stage:

• Blue stain fungus may not yet be present
• Beetles may still relocate to nearby trees
• Removing lightly attacked trees does not always stop spread

Blue-Stained Wood

Mountain pine beetles carry a fungus commonly called blue stain fungus beneath the bark.

When blue staining is visible in trunkwood, it usually indicates:

• Beetles successfully colonized the tree
• Beetle development is underway or recently completed
• The tree is unlikely to recover

Blue-stained trunkwood is the material that should be prioritized for removal or proper disposal before beetle flight intensifies.

Common Misconceptions

“All Dead Trees Should Be Removed”

Not necessarily.

Some standing dead trees, also called snags, provide valuable wildlife habitat and may remain standing for decades in appropriate non-hazard locations.

Woodpeckers feed on wood-boring insects within dead trees and help create nesting cavities used later by:

• Bluebirds
• Nuthatches
• Swallows
• Other cavity-nesting species

Many of these birds also consume bark beetles and other forest insects.

In areas away from structures, roads, and access routes, retaining some wildlife trees may support long-term ecosystem health.

What Material Actually Matters?

One common misconception is that all slash material contains mountain pine beetles.

In reality, mountain pine beetles primarily live beneath the bark of larger trunkwood.

They are generally not found throughout:

• Needles
• Small branches
• Slash piles

Most branches and slash can often be taken later to slash and mulch sites for grinding.

The highest concern is infested trunkwood with active beetles beneath the bark.

Forest Health and Wildlife Habitat

Standing dead trees can provide important habitat for decades.

Over time:

• Woodpeckers excavate cavities
• Wood softens and decays naturally
• Additional birds and wildlife move in
• Insects help recycle nutrients back into the ecosystem

In some forest management approaches, retaining at least several wildlife snags per acre is recommended where safe and appropriate.

This is especially applicable in areas where dead trees already exist from previous mortality events.

The Outbreak Is Still Expanding

The current outbreak has been building locally since approximately 2020.

At this time, the infestation is concentrated primarily within portions of Black Forest, but beetle activity has also spread into:

• Falcon Fire Protection District
• Areas near Tri-Lakes
• Additional portions of eastern El Paso County

Mountain pine beetle outbreaks can expand rapidly once populations increase.

Without early identification and management of newly infested trees, outbreaks may continue growing across the region.

Mountain Pine Beetles and Long-Term Forest Restoration

Mountain pine beetle management is not a one-season project.

Long-term forest resilience involves balancing:

• Wildfire mitigation
• Defensible space
• Forest density
• Wildlife habitat
• Ecosystem health
• Future forest regeneration

The goal is not simply to remove trees, but to create healthier, more resilient forests over time.

Learn More

Additional resources:

• Colorado State Forest Service: Mountain Pine Beetle Information
• 2025 CSFS Forest Health Report
• Black Forest Fire Rescue Firewise Program
• Additional Resources handout May 16 2026

About the Contributor

The information, field observations, photographs, and educational materials on this page were generously provided by Judy von Ahlefeldt, a longtime Black Forest resident, naturalist, and forest ecology educator with decades of experience studying ponderosa pine ecosystems, wildfire behavior, mountain pine beetles, wildlife habitat, and forest restoration in the Black Forest region.

Judy has spent many years documenting local forest conditions, beetle activity, vegetation patterns, wildlife habitat, and ecological changes across eastern El Paso County. Her work emphasizes long-term forest health, defensible space, ecosystem resilience, and the importance of balancing wildfire mitigation with wildlife habitat and restoration goals.

The photographs and educational information shared throughout this page are based on field observations and monitoring conducted in Black Forest from 2020 through 2026 and are used with permission to support public education and community awareness.