What Trees are Attacked?:
Trees favored by the mountain pine beetle (Dendroctonus ponderosae) are lodgepole, ponderosa, sugar and western white pines. Outbreaks frequently develop in lodgepole pine stands that contain well-distributed, large-diameter trees or in dense stands of pole-sized ponderosa pine. Extensive outbreaks can kill millions of trees.
How are Trees Killed?:
The small, black mountain pine beetle begins attacking most pine species on the lower 15 feet of the trunk. These trees are generally killed by beetles of a single generation.
Except when adults emerge and attack new trees, the mountain pine beetle completes its life cycle under the bark. They effectively girdle the tree when building egg and feeding galleries in the innerbark. The first sign of an infested tree is generally discolored needles that quickly turn completely brown.
Except when adults emerge and attack new trees, the mountain pine beetle completes its life cycle under the bark. They effectively girdle the tree when building egg and feeding galleries in the innerbark. The first sign of an infested tree is generally discolored needles that quickly turn completely brown.
Prevention and Control:
Thinning thick stands of pines to moderate stocking levels and multiple age groups is the most effective method to minimize a mountain pine beetle epidemic. Approved insecticides can be effective but are expensive and only used in high value stands of trees.
