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Beetles and the Decline of Western Pine Forests

The current fast-moving beetle epidemic is bigger than any other in recorded history

The native mountain pine beetle, no bigger than a grain of rice, is responsible for killing millions of acres of pine trees in the western United States. The current fast-moving beetle epidemic is bigger than any other in recorded history. This particular epidemic was triggered by an extended drought, warmer than usual winters, and aging forests; conditions that weaken the pine trees and provide a perfect habitat for beetles. Traveling through our western U.S. coniferous forests, you can see entire landscapes turning red and brown as trees die.The beetles bore into the bark of pine trees, lay eggs, and introduce a blue stain fungus which blocks the flow of water and ultimately kills the tree. Adult beetles emerge from infested trees the following summer, traveling up to several miles to attack new trees. Unfortunately, the beetle epidemic cannot be stopped; however, steps are being taken to lessen the impacts. Foresters are able to protect some high value areas, such as homes and campgrounds, by removing recently infested trees and using insecticides on individual trees. This significant change in the forest landscape will influence fire behavior. The U. S. Forest Service, other agencies, local communities, and property owners are working together to remove dead, dying, and hazardous trees. This will help protect people, roads, trails, powerlines, campgrounds, other facilities, and critical watersheds.When the beetles run out of mature trees to infest, or beetle larvae are killed during an unusually cold winter, population numbers will decline. Periodic beetle epidemics are a natural part of the forest system and represent one of the ways nature rejuvenates forests. Mountain pine beetles generally do not attack small pine trees, or other tree species such as fir, aspen, or spruce. These young trees will make up the next forest.

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