Mountain pine beetle populations reached epidemic level on the Hebgen Lake Ranger District in 1970. Infested area increased from 6,680 acres in 1970 to 78,000 acres in 1977. Buildup ratio of trees killed in 1976 to trees killed in 1977 is 1:8. Approximately 1,700,000 trees, containing 175 MMBF of merchantable timber, are currently infested. An accelerated program of logging infested trees and silvicultural treatment to reduce the inventory of large diameter trees is recommended. In high use areas (campgrounds and administrative sites), 3,027 trees are currently infested. Buildup ratio is expected to exceed 1:1 in 1978. In high use areas all green lodgepole pine 7 inches d.b.h. and larger, which are to be retained, should be sprayed with the protective spray Sevimol 4. Infested trees should be removed prior to July 1, 1978. Trees that have been dead for several years may be a hazard and should be removed.