COLORADO — Spruce beetles are continuing to cause problems in Colorado, already killing around 3.5 million acres of trees.

To help curb the issue, the Colorado State Forest Service does an annual aerial survey to help track where pest infestations are spreading.

The new information helps focus efforts where they’ll make the biggest impact, from preventive spraying of healthy trees to removing infested ones. The survey also gives insight into areas that could be prime for wildfire growth, so the forest service can thin certain spots to make the forest more resilient to future fires.

“So that we are fewer trees. And the few trees that do remain can be more vigorous and be able to defend themselves. Once a fire occurs, those heavy trees that are now laying on the floor burn much, much hotter. And make getting in there and dealing with wildland fire and the effects of that fire much more difficult,” said Dr. Dan West, an entomologist with Colorado State Forest Service.

Colorado State Forest Service said spruce beetles are the most damaging pest to state forests for the 9th consecutive year. The aerial survey shows bark beetle infestations spread in 2020 and moved into new areas. They’re now affecting around 80% of state forests.

In 2020, severe drought weakened trees and intensified the spread of beetle infestations. Foresters say beetle-killed trees offer more fuel for wildfires. We’ve seen that with recent fires in Colorado, especially the historic fires of 2020 and the biggest ones in state history.

State foresters encourage you to reach out to your local office. They will come out and look at the trees on your property, make sure they’re disease free and work with you on home prevention.

According to the study, the Spruce beetle affects high-elevation Engelmann spruce. Newly infested forests include eastern Gunnison and western Chaffee counties. Both counties are experiencing severe infestations. Beetle outbreaks in Huerfano and Custer counties continue to expand as well

Spruce beetle populations also increased in Hinsdale, San Juan and La Plata counties. Since 2000, the spruce beetle has affected at least 1.88 million forested acres in Colorado. The Douglas-fir beetle continued to invade Douglas-fir trees in central and southern Colorado, particularly in Gunnison, Saguache, Hinsdale and Mineral counties, where infestations are severe.

The survey was led by Colorado State Forest Service and the USDA Forest Service of the Rocky Mountain Region. Every year, the agencies aerially monitor forest health conditions on millions of forested acres across the state. Due to COVID-19 protocols, 16.3 million acres were monitored in 2020 compared to 30.2 million in 2019.