Mountain pine beetle (Dendroctonus ponderosae) is an insect pest. It was first detected in Washington in 1955.
Mountain pine beetles inhabit pines, particularly the Ponderosa Pine, Lodgepole Pine, Whitebark Pine, Scots Pine and Limber Pine. The bristlecone pines and pinyon pines are less commonly attacked. During early stages of an outbreak, attacks are limited largely to trees under stress from injury, poor site conditions, fire damage, overcrowding, root disease or old age. As beetle populations increase, the beetles attack the largest trees in the outbreak area.