Mountain Pine Beetles May Fly Earlier This Year Says Colorado State Forest Service

The mountain pine beetles that have killed millions of Colorado pines in recent years may already be flying, earlier than typical summer dispersion dates.

“I’ve already begun hearing reports of beetles flying north of Red Feather Lakes,” said Sky Stephens, Colorado State Forest Service forest entomologist, citing observations from other beetle experts in northern Colorado.

The historical peak for mountain pine beetle emergence in Colorado’s lodgepole pine forests has been mid-to-late July, while that from ponderosa pines usually occurs in early August. However, Dave Leatherman, a retired CSFS forest entomologist, predicted an earlier-than-usual emergence of adult beetles this year after surveying lodgepole and ponderosa pines northwest of Fort Collins in late May.

“The beetles already appeared to be in advanced stages of development,” Leatherman said. “My guess was that emergence from these trees certainly would occur before the expected peak.”

Stephens said landowners may still have time this summer to protect their trees from the beetles, if they haven’t already taken action. Preventive chemical and pheromone treatments can be applied to non-infested trees. Chemical sprays generally are recommended to prevent infestation in a small number of high-value trees, while pheromones may deter the beetles from infesting larger stands.

“Before applying preventive treatments, landowners should contact their local CSFS district office to discuss the options that best meet their specific forest management goals,” Stephens said. The CSFS recommends using licensed pesticide applicators to apply chemical products, and emphasizes that landowners applying treatments themselves should carefully follow all product label instructions and warnings.

Stephens said that prior to applying treatments, it is important to confirm that a tree hasn’t yet been infested, as there is no effective treatment available to save mountain pine beetle-infested trees. Trees in the “too late” category can be identified by trunks peppered with popcorn-shaped masses of expelled tree resin and boring dust in bark crevices or at the base of the tree.

According to aerial detection surveys conducted last summer, five Front Range counties – Larimer, Boulder, Clear Creek, Gilpin and Park – suffered 80 percent of all new mountain pine beetle activity in 2009. The beetles have impacted 2.9 million acres of Colorado forest since the current infestation began in 1996.