Survey: Beetles infested half-million acres of Larimer County pines last year

In 2011, 587,000 acres of pine trees in Larimer County showed some level of active infestation by the mountain pine beetle.

That finding is among the results of an annual aerial insect and disease survey released by the Colorado State Forest Service and U.S. Forest Service in February.

For the second consecutive year, the northern Front Range experienced the highest mortality rates affecting ponderosa, lodgepole and five-needle pine trees, according to the survey. More than 3.3 million acres have been invaded by mountain pine beetles in Colorado since the first signs of the outbreak in 1996, making the spread of the insects the most significant forest health concern statewide.

Although an additional 140,000 acres of trees killed by the pine beetles were detected across the state in 2011, the epidemic has slowed down in many areas. Foresters and land managers are now focused on removing standing dead trees that pose a threat to human safety.

The aerial survey data also indicated that spruce bark beetles continued to spread at higher elevations, especially in southern Colorado. Statewide, there were about 262,000 acres of dead spruce trees in 2011, which brings the total affected acreage since 1996 to 741,000.

Jeff Jahnke, state forester and director of the Colorado State Forest Service, part of the Warner College of Natural Resources at Colorado State University, said that ongoing forest management can help prevent such extensive insect outbreaks in the future.

“Active forest management on both public and private lands can lead to healthier trees on the landscape and create the diversity necessary to reduce future large-scale insect epidemics,” Jahnke said. “If we don’t plan now for ongoing management of these forests, we will set the stage for another mass disturbance like the current bark beetle epidemic.”

To view the full aerial survey results, go to the US Forest Service website.