Mountain pine beetle populations reached epidemic levels in 1972 in the Stoney Creek drainage, Ninemile District, Lolo National Forest, Montana. A total of 8,082 trees with an estimated volume loss of 34,356 board feet has occurred from 1972 to 1974. Buildup ratio was 1:1.2 from 1972 to 1973, and 1:1.8 from 1973 to 1974. Losses are expected to increase in 1975. Commercial thinning is recommended in unthinned stands.