Silent Insect Killer Ravages American West

Mar. 28, 2008— -- The American West is under attack by a silent killer that's causing some of the worst-ever destruction to hit the nation's forestland: the mountain pine beetle.

"People are looking out their windows and seeing dead trees where they used to see green," said Sandy Briggs from the Forest Health Task Force in Aspen, Colo.

Despite their small size (approximately 5 millimeters when fully grown), these beetles are doing enormous damage, wiping out millions of acres of lodgepole pines as an epidemic of them explodes across the West.

"We have about 1,500,000 acres of trees that have been infested," said Clint Kyhl, an incident commander for the U.S. Forest Service, referring to devastation in Colorado and Wyoming alone. That's roughly twice the size of Rhode Island.

The epidemic began in 1996, but in the last year it has really taken off. Five years from now all of Colorado's lodgepole pine forests, another 6 million acres, will be wiped out, and the beetles are expected to infest the entire West over the next 15 years, state forestry officials say.

Colorado is just one of eight states across the West that has been impacted, along with Wyoming, South Dakota, Washington, Oregon, Utah, Montana and Idaho, as well as large parts of Canada in British Columbia and Alberta.

"The forest conditions were just right — we had all of these older forests with lots of larger-diameter old trees — the bigger trees produced more beetles so it really expanded quickly," explained Bob Cain, a Forest Entomologist with the U.S. Forest Service.

In addition, recent drought conditions have made the trees even more susceptible to the insects, and milder-than-normal winters have helped the beetles thrive.

"The bugs cannot survive a cold winter. We have not had a very cold winter for about 10 years," said Rick Cables from the Rocky Mountain Region division of the U.S. Forest Service.

Mostly it's the larvae that do the most damage, feeding on the tree's inner bark and leaving a blue fungus. In effect, the bugs are starving the trees to death.