Our dying forests: Beetles gnawing way through millions of acres across West

Since 1997, a host of native beetle species has chewed through more than 40 million acres of Western forests, according to aerial surveys by the U.S. Forest Service. That’s as much space as all of America devotes to its lawns. And the beetles show no signs of crashing. They kill by burrowing into the fleshy layer of nutrient-conducting phloem — just under the bark — which their larvae eat and effectively girdle. Various bugs have swallowed 2 million acres of Utah forests, a patchwork about as large as Yellowstone National Park. In Montana, with more than 6 million acres of beetle carnage, second only to Colorado, the frost-free season has extended by two weeks in the past half-century. That’s pleasantly milder for people who once routinely bundled themselves against 40-below zero winters, but it’s torturous for pine trees. "In the arid West, you only have a growing season if it has enough water, just like your garden," said Steve Running, ecology professor and University of Montana Climate Change Studies Program director. But the region hasn’t gained water, and most climate models predict it will lose moisture to evaporation even when more falls as snow or rain...more