The mountain pine beetle, Dendroetonus ponderosae Hopk., has been at epidemic levels in second-growth ponderosa pine stands in the Ninemile area of the Lolo National Forest and surrounding private lands since 1969. An impact survey, using two levels of photography and a small ground sample, was conducted to estimate a loss of 592,469 board feet IP of ponderosa pine on 2,592 acres of infested land. The infestation is expected to continue at about the same level in 1973.