Mountain pine beetles on rise in Colorado

Posted: June 29, 2012

The mountain pine beetle is about a quarter-inch long, has a one-year life span, is native to North America and, if left unchecked, this little bugger can kill forests.

That is the fear of forestry experts throughout Douglas and Elbert counties, who are keeping their eye on trees that have succumbed to the beetle.

Michael Bahm is a forestry consultant for Castle Pines who spent 30 years with the state forest service. The Castle Rock resident now spends his retirement as a consultant traveling Douglas and Elbert counties, which he said is in the midst of a 20-year cycle of high mountain pine beetle activity.

Source: Our Colorado News

In the last four years, Bahm has seen infected trees in Castle Pines increase from one tree in the first year to 40 trees in the third year and about 170 infected trees last year. The numbers don’t reach the epidemic standard of two trees per acre, but the increase remains alarming, he said.

The trend is the same from northern Douglas County through the Black Forest, east of Franktown and south past Monument Hill, Bahm said.

“Dry weather escalates the problem because the trees get under stress, and that’s what mountain pine beetles like, is stressed trees,” he said.

Mountain pine beetles typically seek out trees that are distressed or weakened by overcrowding or drought conditions. Trees that are not thinned are competing for moisture and nutrients, Bahm said, making them more vulnerable to beetle attack.

Mature insects emerge between mid-July and mid-September to find a new host tree, usually near the tree where they emerged. The beetle will bore into the new host tree, where they mate and produce about 75 eggs, according to the Colorado State University Extension Office.

Signs of a mountain pine beetle attack include popcorn-shaped masses of resin, called “pitch tubes” on the trunk of a tree, boring dust in bark crevices on the ground and evidence of woodpecker feeding on a tree. Once a tree is infested, nothing practical can be done to save the tree, according to the extension office.

“You lose at least two trees for every infested tree if you don’t treat it,” Bahm said. “That’s why you’ll see those groups get larger and larger and larger until the population abates. That’s usually a cycle of several years.”

The landscape managers at Castle Pines hope to get ahead of the beetles before that cycle gets out of hand.

Dave Cooper, the homeowner association landscape technician, works with Bahm to help homeowners with their beetle-kill trees before an infestation spreads. While homeowners in Castle Pines are diligent about protecting their forest, he is more concerned about those trees close to but outside of the upscale subdivision.

Cooper is keeping his eye on a small grove of infested pine trees just south of the Happy Canyon exit. About 20 dead pine trees on the west side of Interstate 25 appear to be in no-man’s land, but have in recent years proven a feast for a host of mountain pine beetles, Cooper said.

His inspection confirmed there are 20 dead or dying trees on the property, with nine of those trees impacted by active infestation. Cooper hopes to identify the owner of the property where the trees are, in hopes of notifying the landowner and stopping the infestation before it spreads.

“The way the pine beetles attack, there are 20 now, next year there will be 50 and the year after that there could be 150,” Cooper said. “Several appear to be in the right-of-way but the majority appear to be on some private properties that are fairly close to I-25. Those trees need to be removed.”