Colorado Landowners Should Protect Against Pine Beetles by Early Summer

Millions of adult bark beetles will set off in search of new hosts this summer in Colorado. Landowners attempting to prevent the spread of the beetles must act soon to effectively protect their trees, according to Sky Stephens, forest entomologist for the Colorado State Forest Service.

“Colorado landowners at risk for mountain pine beetle infestation need to take steps to protect their trees before the beetles fly and infest new trees,” said Stephens. Mountain pine beetles generally depart dying trees to seek new hosts starting in early July.

According to aerial detection surveys, the mountain pine beetle epidemic moved closer to population centers along the Front Range in 2009. Five area counties (Larimer, Boulder, Clear Creek, Gilpin and Park) suffered 80 percent of all new mountain pine beetle activity, representing more than 300,000 acres.

While there is no effective treatment available to save trees already infested by mountain pine beetles, Stephens said landowners can effectively fight the insects on two fronts. Preventive treatments can be applied to non-infested trees; trees that are dead or dying from beetle infestation should be “sanitized,” or treated to kill late-stage larvae and pre-emergent adults. Sanitation involves cutting the trees down and then employing a proven method to kill beetles living under the bark, such as removing the bark itself, or chipping or burning the wood.

Chemical sprays are generally recommended to prevent infestation in a small number of high-value trees, while pheromones may deter the beetles from infesting larger stands. Stephens said that several new pine beetle-prevention products have also hit the market more recently, but haven’t yet been extensively tested for safety and effectiveness.

“When considering preventive treatments, landowners should contact the nearest Colorado State Forest Service district office to discuss the best options to meet their specific forest management objectives and address local conditions,” Stephens said. She also suggested that landowners follow all product label instructions and warnings, and recommends using licensed pesticide applicators to apply chemical products.

The Colorado State Forest Service provides more information about mountain pine beetle treatments at