First, the good news about the bark beetles that have been ravaging western forests for almost a decade: A new report indicates they may finally have eaten themselves out of house and home after killing conifers on some 42 million acres of forests at prime fish and wildlife altitudes.
Now the bad news: The same report showed evidence that warm winters have allowed the bugs to push into higher altitude areas where cold temperatures once held them back.
The U.S. Forest Service report said aerial surveys showed beetle-killed trees on 3.8 million acres of public down, the second consecutive year of a decline, and less than half of the nine million trees killed in 2009.
Researchers say while pine and spruce beetle outbreaks are cyclical in the west. Traditionally their advances were stopped because the bugs could not withstand winter temperatures that dropped well below zero for long periods of time - routine in the mountain West, until recently.