An increase in mountain pine beetle outbreaks in North America has been linked with climate change.
A study of the number of trees killed by bark beetles in Oregon and Washington over 30 years suggests climate is having a significant impact on beetle activity.
Warmer winter temperatures and drought stress on trees are among the factors influencing larger outbreaks.
Scientists looked at beetle activity over a greater time period and scale than previously studied.
Read more at US Forest Service and University of Idaho