The spruce beetle, which has significantly damaged the Rio Grande National Forest, is rapidly making inroads into the San Juan National Forest.

The U.S. Forest Service held a meeting this week to kick off a planning process for how to deal with the beetle and the trees it kills while feeding.

“We’re not coming to you with a proposal of what we want to do,” said San Juan National Forest Supervisor Kara Chadwick at Tuesday night’s meeting. “This is designed to give us all a common understanding of spruce-beetle dynamics and the current epidemic and to discuss what we can do about it on the ground.”

In recent years, beetles have damaged 23,000 acres in La Plata County and about 209,000 of the 1.8 million acres of the San Juan National Forest.

Forest Service entomologist Tom Eager gave the standing-room-only crowd in the Vallecito Room at Fort Lewis College a primer about the beetle, one of many predators attacking Colorado forests, along with mountain pine, western pine, pinyon ips and Douglas fir beetles.

“These are predators, just like a pack of wolves hunting a wounded moose,” Eager said. “For them, a blow-down of old spruce is like a McDonald’s hamburger stand.”

The beetle, which has a “better sense of smell than a bloodhound,” primarily attacks Engelmann spruce, he said, although a large stand of blue spruce by Cascade Creek has been hard hit.

Female attack beetles are the advance scouts, seeking older spruce that are generally distressed in some way, perhaps blown over in a wind or enduring a drought. When they find a prime candidate, Eager said, they send out a chemical to attract other female and male spruce beetles. The beetles burrow under the bark of the spruce, lay their eggs and feed on the phloem layer, which is a sugar, he said.

“People say, ‘They’re insects, why don’t they just freeze in the winter?’” Eager said. “They convert that sugar into glycol, which is antifreeze. They’ve been in a symbiotic relationship with the spruce for millennia, and they’ve survived many cold winters.”

The key to stopping the cycle, he said, is for an extremely cold, dry winter, so the beetles’ trees aren’t insulated by snow.

“We haven’t seen one of those in a while,” Eager said. “And the way things are going, we may not see one anytime soon. Climate change is the wild card here.”

While a number of ways to deter or kill spruce beetles have been developed to work on small areas or individual trees, he said, there’s nothing yet that will work on the scale of the landscape in the San Juan.

The Forest Service will hold open houses at the three districts within the San Juan National Forest – Dolores, Columbine and Pagosa Springs – sometime in the next couple of months, Chadwick said, and may plan a field trip to Wolf Creek Pass or into the Rio Grande National Forest so people can see beetle damage first-hand.

Forester Laurie Swisher, who manages a vegetation database, said only about 20 percent of the areas in the San Juan National Forest are appropriate for management techniques. The rest are either in wilderness or special management areas or are areas too inaccessible or fragile to manage. The Forest Service would like the public to comment about how to handle the areas where the agency can do mitigation and restoration work.

Swisher said the first priority is safety. The agency wants to make sure people cannot be harmed by trees falling on trails, roads and campgrounds, and that power lines are not damaged.

“Then we want to look at the potential for salvage logging of the dead trees,” she said. “We could use the timber sales receipts to put back into restoration where we did the logging.”

Logging can be a touchy word for environmentalists, but it may allow for a more diverse forest inventory that would be more resilient to future insect attacks, Eager said.

“One of the reasons we’re worried about saving old spruce is a human value,” he said after being asked if aspen, which are often the first trees to grow in destroyed areas, might create the largest aspen forest in the country here.

“We’re worried our grandkids aren’t going to see the same kind of forests we did,” he said. “But this is not all doom and gloom. Aspen come roaring back into these areas like a freight train, and you’re right, for tourism, that could be a jewel.”

abutler@durangoherald.com

Beetle facts

In 2014, 480,000 acres in Colorado were affected by the spruce beetle.

Of the 13.2 million acres managed by the U.S. Forest Service in Colorado, more than 75 percent are out-of-bounds for any forestry management between being in protected wilderness areas or being located on slopes that are too inaccessible or fragile for any management practices.

Of the 1.8 million acres in the San Juan National Forest, about 209,000 acres have been affected by the spruce beetle.

Only 20 percent of the 209,000 acres in the San Juan National Forest are eligible for any forestry management techniques.

The average spruce beetle has a two-year lifespan.

A female attack spruce beetle lays between 80 and 150 eggs after boring below the spruce’s bark.

About 20 percent of female attack spruce beetles attack and lay eggs in more than one tree.

Up to 125 other organisms, including mites and fungi – a whole series of parasites and predators – enter a spruce with the beetle.

The average flight range for a spruce beetle is about 1 mile, but in the summer, they often are picked up by warm air currents and can travel much farther.

Learn more

Visit www.youtube.com/watch?v=DXHZcybbQQo on Fort Lewis College’s YouTube channel to view the spruce-beetle informational meeting held Tuesday.

The Colorado Forest Service and the FireWise Council of Southwest Colorado will host the Southwest Colorado Forest Health Workshop from 5:30 to 7:30 p.m. April 15 at the La Plata County Fairgrounds Extension Building, 2500 Main Ave. The workshop will cover issues such as the spruce, mountain pine, western pine and Douglas fir, pinyon ips beetles. The workshop is free, but an RSVP is requested for planning purposes to the state Forest Service at 247-5250.

Visit www.csfs.colorado.edu to learn more about the Colorado Forest Service.

Visit www.southwestcoloradofires.org to learn more about the FireWise Council.