About 6.3 billion dead trees are still standing in 11 Western states, up from 5.8 billion five years ago, according to U.S. Forest Service statistics compiled for The Associated Press.

Since 2010, a massive infestation of beetles has been the leading cause of tree mortality in the West and now accounts for about 20 percent of the standing dead trees, the Forest Service said. The rest were killed by drought, disease, fire or other causes.