Pine Beetle Epidemic Continues To Slow, While Spruce Beetles Are Just Getting Started

The results of the U.S. Forest Service’s annual aerial survey are in, and it appears that the pine beetle infestation that has caused epic devastation in many western states is continuing to grow, but at a much decreased rate. In the Black Hills of South Dakota, the beetles spread to 34,000 new acres in 2013, an enormous area of land, but far less than in 2012, when 67,000 new acres came under attack.

“We still have an epidemic, but our encouraging news is those declines relative to the past,” Craig Bobzien, Supervisor of the Black Hills National Forest told the A.P. “We still are growing, but that rate of spread is declining..

In Colorado the survey found that the acreage of trees infected by the pine beetle has dropped to its lowest in 15 years — 97,000 acres in 2013.

“They’ve kind of eaten themselves out of house and home,” Aaron Voos of the Forest Service told Wyoming Public Media. “All of the trees that were susceptible to attack … have been either eaten and are now dead and dying, or they were able to fend off the epidemic and have developed some sort of resiliency.”

While the rate of infection of the epidemic does appear to be finally slowing down, the dramatic die-off of beetles some scientists predicted would be the silver lining of this winter’s bitterly cold temperatures, may never come.

The deep freeze is most likely too little, too late in the season. By the time serious cold hit the West, pine beetles are usually burrowed deep within the insulated trunks of trees and have winterized their systems with a sort of natural antifreeze that protects them. In order for cold to harm the beetles at this stage, the mercury needs to drop to about minus 30 to minus 40 degrees, and stay there for many days.

Cold weather is most lethal to pine beetles in the spring and fall — seasons which in some parts of the country seem to be almost disappearing.

“At that time of year, cooler conditions much warmer than this could have an effect,” Roy Renkin, a Yellowstone National Park vegetation specialist told the Billings Gazette.

Unfortunately, the Forest Service survey also found that for the fifth consecutive year, a different, but related species of tree-killing beetle, the spruce beetle, continued to infest an ever larger area in Colorado. In 2013, over 216,000 acres of Colorado forest were affected by the pest, in 2012, the beetles laid claim to around 183,000 acres of previously healthy forest.

While the spruce beetles are clearly on the move, forest managers don’t expect to see anything like the destruction caused by the pine beetle. That’s because spruce beetles attack Engelmann spruce and blue spruce which are much less common than the lodgepole, limber and ponderosa pine that succumb to pine beetles.

To date, spruce beetles have killed nearly 2 million acres of forest in Wyoming and Colorado since the mid 1990s — just a fraction of the area devastated by pine beetles during the same time.

The post Pine Beetle Epidemic Continues To Slow, While Spruce Beetles Are Just Getting Started appeared first on ThinkProgress.