It’s cold, but enough to kill Colorado’s bark beetles?
December 11, 2009
FRISCO, Colo. – If only pine beetles could feel windchill like the rest of us.
Recent cold, windy weather may have been bitter for humans in Colorado, but the pine beetle larvae snuggled up in the bark of area lodgepole forests are doing just fine, according to U.S. Forest Service entomologist Bob Cain.
“It would need to get even colder to have significant mortality,” Cain said.
The mountain pine beetle has devastated local forests during the last several years. Hillsides with vast swaths of red and brown trees mark their paths. The insect spends the winter burrowed under the bark of lodgepole pine trees.
Nighttime temperatures have fallen as low as 20 degrees below zero lately, but the beetles don’t die off until the thermometer dips down to about 35 below.
“And the bark provides some insulation. So it has to be that cold for long enough to get the temperature under the bark that cold. If you just have an evening or two, it’s probably not enough,” Cain said.
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Cold snaps earlier in the season can have a greater impact on beetle populations than those in the depths of winter.
“As you go into the winter, the larvae synthesize glycerol, which is an anti-freeze,” Cain said.
But for the most part, the Western Slope’s fall was relatively mild.