"The Fraser fir is . . . in peril, badly affected by this adelgid," said Andrew Liebhold, a research entomologist for the U.S. Forest Service in Morgantown, W.Va.
"I don't expect them to totally disappear in my lifetime," Liebhold said. But the die-off of Fraser firs at Mount Mitchell is a major concern. Younger trees are growing there now, "but the danger is when they're older" and reach 20 feet, a height at which, for unknown reasons, adelgids crave their sap.
Balsam firs, including the Canaan and Fraser varieties, are common in North America, especially from Massachusetts to Maine and the Canadian provinces of Quebec and Ontario. They thrive in cold areas mainly because adelgids struggle to survive in exceedingly cold temperatures.
But farther south, the trees struggle. Climate change could worsen the problem, Powell said, if temperatures warm in the northern range, Massachusetts and much of New England.
Christmas trees in American forests are home to birds, and, in the Canaan Valley, the West Virginia northern flying squirrel, which was recently taken off the endangered species list.
"It's part of our national heritage, people have gone out to get their own tree for generations, and this is the prize tree they went for," Powell said.
The balsam woolly adelgid is an uninvited guest in North America, but it's been around so long that it seems like part of the family. It came from Europe before the 1900s, when there were no regulations guarding against invasive pests, Jill Sidebottom, a forestry extension specialist at North Carolina State University, wrote in an essay last year.
It probably arrived in New England and moved into the southern Appalachians in the 1950s, where the population probably exploded. It "has caused the destruction of the Fraser fir in the natural stands," Sidebottom wrote.