Steamboat Springs The spruce beetle epidemic has swelled faster than U.S. Forest Service officials anticipated and is threatening trees within the Steamboat Ski Area.
The beetle population increased dramatically within the Routt National Forest this year, said Andy Cadenhead, U.S. Forest Service team leader for beetle suppression.
Aerial surveys done every year from 1996 through 2000 showed between 40 and 80 trees killed each year by spruce beetles. But aerial surveys done this past July showed spruce beetles had killed about 10,000 trees, and the number is increasing, he said.
Since the aerial survey, crews have been in the forest examining infested trees.
"We are finding a lot more than 10,000," he said. "This has happened a little quicker than we expected."
Weather and the 1997 Routt Divide Blowdown are to blame for the beetle boom. Warm, dry weather the past two summers and fall has allowed the beetles to double the pace at which they normally multiply, Cadenhead said.
The beetles have a plentiful supply of trees on which to feed. In 1997, winds exceeding more than 120 mph toppled more than 4 million trees on 13,000 acres within the Routt National Forest.
"The beetles are picking the best trees," Cadenhead said. "Right now, their nutrition is the best it can be."
Spruce beetles seek the fallen trees to feed on the cambium layer under the bark, while the dying trees' natural defenses diminish. When the blowdown happened, the beetles' habitat increased dramatically.
A large population of beetles doesn't need dying trees to live in. Instead, about 2,000 beetles collectively attack one standing tree, exhausting the tree's defenses and eventually killing it.
From that one tree, between 30,000 and 40,000 beetles can be produced.
"The numbers are astronomical," Cadenhead said.
To combat the beetles, the Routt National Forest has 40 people doing beetle suppression and surveys.
"Can we stop this epidemic?" Cadenhead asked. "The answer is no. We have thousands of acres. We can't stop the epidemic. We are choosing to protect certain areas."
Crews are concentrating on protecting the ski area, campgrounds and scenic corridors.
Suppression efforts include spraying pesticides and cutting and peeling trees.
So far at the ski area, crews have found infested trees on top of Mount Werner.
Suppression crews have cut and peeled 530 trees on the ski area this fall. Crews continue to peel the base of standing trees to kill beetles. Concentrated efforts to remove infested trees have also occurred at numerous campgrounds, including Hahn's Peak, Seedhouse, Granite Summit and those on Rabbit Ears Pass.
"We have a good chance at protecting some of the areas," Cadenhead said.
Because of early snowfall, crews are not spraying pesticides at campgrounds. Pesticides are not being used if there is a potential exposure to water sources, including snow, he said.
"We are gearing up to spray next spring," he said.
Cadenhead said the beetle epidemic is natural, and so is beetle infestation in live trees. He said the potential death of every mature spruce tree in parts of the Routt National Forest also is natural.
In fact, the forest depends on the infestation for regeneration. The spruce beetles will infest only older spruce trees, which will allow younger trees to grow.
The life cycle for spruce trees is between 150 and 300 years, Cadenhead said.
"Our spruce is between 100 and 150 years old," he said. "The trees are ripe."