Dendroctonus jeffreyi, known generally as the Jeffrey pine beetle or mountain pine beetle, is a species of crenulate bark beetle in the family Curculionidae. It is found in North America. The Jeffrey pine beetle is monophagous on the Jeffrey pine tree, a dominant yellow pine and most concentrated in areas ranging from Southwestern Oregon to Baja California to western Nevada. In its native range, it causes a significant amount of damage as large numbers of tree mortality have been documented. It is known to cause significant changes to the composition and structure of the Jeffrey pine tree.