The recent cold snap across the Rocky Mountains have people wondering whether the cold temperatures — which reached well into the double-digits-below-zero for several nights in a row and as low as -38F near Steamboat Springs, Colorado — will have any impact on the mountain pine beetle populations decimating the region's lodgepole pine forests.
Unfortunately, most scientists seem to agree that while it got cold enough in Colorado over the last week, those cold temperatures were not sustained for a long enough period of time to kill off those populations, although it may have weakened and stressed them somewhat.
So what exactly is the magic number needed to kill off the beetles? Most scientists say it takes about a week or more of -30 F temperatures to freeze mountain pine beetles:
Peter Kolb, Montana State University (Missoulian):
"The magic number is often 30 to 40 below zero," said Kolb after another western cold spell in early January. "The mountain pine beetle has adapted to survive down to around that temperature. When we get colder temperatures for prolonged periods of time, it does stress them."
Sky Stephens, entomologist with the Colorado State Forest Service (7News):
...studies show that pine beetles are only affected when the temperature plummets to minus 30 Fahrenheit for 72 consecutive hours.
Janelle Smith, US Forest Service spokeswoman (Denver Post):
"We need it to be sustained, at least two or three weeks" with temperatures of minus 20 or lower, Smith said. "These short cold snaps will not do the job."
Rick Newton, US Forest Service District Manager in Silverthorne, CO (9news.com):
"Historically, cold weather can potentially reduce the population or slow them down. In some cases if it’s cold enough actually kill a sizable population," said Newton.
"We generally look at somewhere between 10 days and two weeks of 20 below zero weather," Newton said.
Mountain pine beetles are native to the forests of the North American West, but in recent years, warmer winters and sustained droughts combined with a historical legacy of fire suppression have allowed the deadly critters to flourish.
Since 1996, mountain pine beetles have infested 4.6 million acres of forests in Colorado and Wyoming alone.