"Recent inspections in Jefferson County showed larvae at a typical stage for a May emergence."”

GILPIN COUNTY — The Gilpin County CSU Extension Service hosted a March 31 workshop on pine beetles at the Gilpin Library. The meeting had a good turnout of 37 virtual attendees and 30 in person. It focused on the status of the epidemic and treatment methods for dealing with infected trees.

Gilpin County CSU Extension Agent Jennifer Cook moderated the meeting. Dan Allen and Collin Wassink from the Colorado State Forest Service (CSFS) gave slide presentations on the status of the current epidemic, the life cycle of pine beetles, and recommended management practices. Kelby Woodard from the Clear Creek Watershed and Forest Health Partnership (CCWFHP) gave a presentation on community wildfire risk.

Allen started the meeting by discussing the causes and size of the current Mountain Pine Beetle epidemic. A dry winter and warm temperatures benefited the beetles, and they are expected to fly at the end of May and early June through the first of September. There were concerns that the beetles would emerge early, but recent inspections in Jefferson County showed the larvae at a typical stage for a May emergence.

In contrast to the previous epidemic of 2009-2011, when Mountain Pine Beetles were infecting Lodgepole Pines, this time around they are attacking primarily Ponderosas. The beetles attack mature trees with a diameter greater than six inches. Ecologically, they are beneficial when they kill diseased or dying pines, setting up a burn recovery cycle for the forest.

Allen presented maps showing the spread of the beetles along the Front Range since 2022. The biggest concentrations currently are in southern Gilpin County, but they are spreading northward. Beetles can fly up to a half mile after emerging but can go farther depending on the wind.

Wassink spoke about the life cycle of a beetle from eggs to larvae to pupae to adult beetles. He showed slides of larvae galleries under the bark and the difference between Mountain Pine and Ips Beetle galleries.

There were slides that showed how to determine if a tree has been infected by identifying white pitch tubes on the trunk. A pitch tube is the tree’s way of defending itself by using sap like a water cannon to push the beetle out. Pitching requires the tree to have sufficient water, so droughts and dense stands weaken its ability to resist an attack.

Several management possibilities were presented to deal with an infected tree. The recommended solution was to take the infected trees to the Gilpin Slash Site for disposal. Slash from infected trees is not a problem, since the larvae are only in the trunks. The slash can be disposed of along with regular slash. Logs need to be four to six feet in length, with diameters less than 16 inches.

Wassink also discussed prevention methods, including pheromone pouches and pesticide spraying. Mitigation of weaker trees so there is more water for the remaining trees is also a management strategy.

 Recovery options after beetles have infected a property include species and age stand diversity. Wassink emphasized that beetles are part of the ecosystem and have a role in maintaining healthy forests.

Woodward’s presentation was about wildfire risk. He spoke about the factors that contribute to wildfire risk—fuel, weather, topography—and ways to approach mitigation.

Kelby Woodard from the Clear Creek Watershed and Forest Health Partnership (CCWFHP) during a presentation on assessing wildfire risk at Mountain Pine Beetle workshop at the Gilpin Library.

Photo by Wes Isenhart

The one statistic in his presentation that stood out was that 90% of the area that burned in a wildfire in Colorado between 2002 and 2025 started from 3% of the days that had Red Flag warnings. Wildfire risk is highest during Red Flag warning days.

For more information about the pine beetle epidemic or management options like pheromone pouches, contact the Gilpin CSU Extension Service at 303 582-9106 or extension.colostate.edu/gilpin. Prevention methods need to be deployed before the adult beetle’s fly starting in late May.

Use the search term: “Colorado State Forest Service Mountain Pine Beetle” to find the CSFS webpage about Mountain Pine beetles.