KETCHUM, Idaho – The U.S. Forest Service has started spraying Sun Valley Resort’s famous ski area on Bald Mountain with a pheromone intended to turn aside an attack of Douglas-fir bark beetles.
Aerial spraying of the pheromone called methylcyclohexenone started Thursday on about 2,000 acres on the mountain. The pheromone is produced naturally by the beetles and lets other beetles know a tree is already full of beetles.
The Forest Service hopes spraying healthy trees will trick beetles into staying away. Officials say the population of beetles naturally expands following a fire, in this case the nearly 75-square-mile Castle Rock Fire that burned in the region in 2007.
“It allowed the beetle population to explode,” Joe Miczulski, recreation and winter sports specialist for the Ketchum Ranger District, told the Idaho Mountain Express.
Miczulski said a helicopter is being guided with an onboard GPS that has been downloaded with the locations of where to spray.
A second round of spraying is planned for late June to combat the beetles.
“There is always an endemic population,” Miczulski said. “It’s usually small.”