Mountain pine beetles affect pine trees by laying eggs under the bark. The beetles introduce blue stain fungus into the sapwood that prevents the tree from repelling and killing the attacking beetles with tree pitch flow. The fungus also blocks water and nutrient transport within the tree. On the tree exterior, this results in popcorn-shaped masses of resin, called “pitch tubes”, where the beetles have entered. The joint action of larval feeding and fungal colonization kills the host tree within a few weeks of successful attack (the fungus and feeding by the larvae girdles the tree, cutting off the flow of water and nutrients).
Originally called Black Hills or Rocky Mountain Pine beetle. Beetle that feeds on bark; one generation per year. Cylindrical, black adults; the head is obvious from above. About 4-7.5 mm long, indented along the elytra. Larvae are white with a sclerotized head.