We may be winning one beetle battle
ASPEN ” There’s a “no vacancy” sign at Aspen Highlands that seems to be keeping the riffraff away.
Those battling bark beetles are using a pheromone to try to prevent the bugs from invading and killing relatively rare Douglas fir trees at the ski area.
“So far it looks like it’s being fairly successful,” said Jan Burke, a forest silviculturist with the White River National Forest supervisor’s office.
Bark beetles produce a pheromone that is an attractant, Burke said. It tells other beetles something like, “Hey, come join us for a buffet at this old, mature tree.”
When beetles heed the call, they overwhelm a tree’s defenses, lay eggs, and their larvae munch away and eventually kill the trees. The adults fly away and spread the devastation.
Scientists discovered an anti-attractant pheromone for Douglas fir tree beetles “that says no vacancy,” Burke said.
Beetles naturally use an anti-attractant to signal late arrivals when a host tree is occupied to capacity. The Forest Service is duplicating that attractant.
The effort to save the Douglas fir trees at Highlands began after Burke had a bad day on the slopes during the 2004-05 season: “I was fleeing the mountain in extreme humility,” she said.
Being a silviculturist, she noticed woodpecker tracks on some stately old Douglas fir trees along the easiest route off the hill. She pointed them out to a Forest Service entomologist who investigated after the snow melted. He found that a bark beetle specific to Douglas fir was attacking the trees.
The Forest Service and Aspen Skiing Co. stapled tags with the pheromone to about 350 trees that spring. The tags worked well enough that they were reapplied this year, Burke said.
Mac Smith, director of the Highlands ski patrol, said the main stand of Douglas fir at the ski area is located in the P-Chutes, a steep, triangular patch sandwiched between the Thunderbowl and Exhibition chairlifts on the lower the mountain.
Smith said he hasn’t noticed any of the trees dying since the pheromone was first applied.
Burke said there is a functional as well as aesthetic reason for saving Highlands’ stand of Douglas fir. They help stabilize a steep slope, she said.
Douglas fir are relatively rare around the Roaring Fork Valley, according to Burke. Beetles have wiped out patches of them on the opposite side of Ruedi Reservoir from Frying Pan Road and high up in Glenwood Canyon, she said.
Spruce trees and, to a lesser extent, lodgepole pines, are much more common in the national forest surrounding the valley.
Lodgepoles are getting hit hard in Eagle and Summit counties, as the rust-colored trees along Interstate 70 attest.
Different trees attract different pests. “They all have their specific beetles,” Burke said.
Unfortunately, the anti-attractant pheromone has proven effective only on the Douglas fir beetles, so far, she said.