Mountain Pine Beetles (image) Dartmouth College Share Print E-Mail Caption Mountain pine beetles (pictured here) have killed pine forests over more than 140,000 square miles in the western US, but warming winters can't be blamed for the full extent of recent outbreaks in the region, a Dartmouth College and US Forest Service study finds. Credit Jeff Foott Usage Restrictions Must credit Jeff Foott. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.