By Dr. Judith von Ahlefeldt, Landscape Ecologist
Each summer, the Colorado State Forest Service (CSFS) and the national Forest Service (USDA) cooperatively conduct Aerial Detection Surveys (ADS) to monitor the health of forested lands. Each agency uses these results in its respective Forest Health Reports.
In Colorado, ADS collects graphic signatures of healthy and diseased forests that exhibit dead, live, and diseased tree crowns. Using geospatial programs, these data are presented as maps in the annual Forest Health Reports.
A layered, zoomable online map, which focuses on forest insects and diseases, currently features the mountain pine beetle ADS results. Fader (trees that are infested) information, from 2024 infestations reported in 2025 flights, is overlaid in red over a 2022-24 forest health basemap.
The 2025 aerial survey is available now to the public, although the full 2025 Colorado Forest Health report was not yet online in late April.
The graphic below uses a clip from ADS link: https://tinyurl.com/v26n5mpb.
This is presented on the online arcgis hub site as a “map view” of all of Colorado, and you must scroll over to the eastern edge of the mountains and zoom in to find El Paso County and the Palmer Divide jutting to the east into the Great Plains.
The red and gold points and polygons indicate where mountain pine beetles’ yellow-brownish faders were noted in the July-August 2025 aerial detection surveys.
Remember that the faders seen in the summer of 2025 are from trees that faded in 2025, from eggs laid by the previous year’s brood during late summer/fall of 2024. Health reports are dated the same year as the faders and aerial survey flights—not the year the mountain pine beetle’s eggs were laid in the newly infested trees.
The trees, which will fade this spring/summer, and will appear in next year’s 2026 CSFS Forest Health Report (published 2027), are still green, wilting, or yellowing now in May 2026.
Extended growing seasons in recent years, and a short winter with high early spring temperatures this year, may allow mountain pine beetles to mature earlier than the “usual” emergence times of mid- to late July. Some practitioners have already noted a few emergent adults months ahead of normal.
Inspection of this 2022-25 Fader Mortality Map (from west to east) shows isolated small locations of gold (2024) and red (2025) faders in the National Forest northwest of Monument. and north of the 2013 Black Forest Fire burn scar.
Edges of the southeastern Black Forest have significant fader mortality, for both 2022-24 (gold) and 2025 faders (red). Now there are hundreds of acres of dead trees. This map does not show where currently green trees with pitch tubes and blue-stained wood will show up this summer.
It is critical to remove currently infested trees before mid-June all over the Tri-Lakes/Black Forest area to mitigate huge increases of faders next year (green, pitch tubes, and blue stain).
Dr. Judith von Ahlefeldt can be contacted at judithvonahlefeldt@ocn.me.
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