Pine beetle outbreak ends in Colorado

Experts delivered good news about Colorado’s beloved aspen trees, which turn mountainsides bright yellow and orange every autumn: They’re generally faring well after suffering worrisome die-offs from drought in previous years. The U.S. Forest Service and Colorado State Forest Service conduct an aerial survey of the state’s trees every year, and the 2015 survey was released recently. It showed the mountain pine beetle has returned to pre-epidemic levels after attacking more than 5,300 square miles of forest since 1996, leaving large swaths of forest a dull reddish-brown. The epidemic subsided because few vulnerable trees were left for the beetles to infect, the survey found. The beetle primarily attacks tall, slender lodgepole pines, but it also got into larger ponderosa pines. A related insect, the spruce beetle, attacked another 285 square miles of spruce trees last year for a total of 2,500 square miles since 1996. That was a smaller increase than the year before, but Cain said it’s too early to tell whether the epidemic has peaked...more