Natural enemies and life-history traits are described and discussed in relation to the control of Choristoneura je:oensis (on Abies sacliatinensis), Dendrotimus superans (on A. sachalinensis and Picea jezoensis), and Lyniantria dispar (on Larix leptolepis and Betula platyplzylla) in Hokkaido, Japan. Outbreaks of the todo-fir budwonn (C. jezoensis) occurred during 1965-75 in plantations of A. sachalinensis. The population in natural forests, however, remained at low levels during this period. The budworm parasite Lissonota saturator was more abundant in the natural, mixed coni fer/broadleaf forests than in the todo-fir plantation. Control methods utilizing life-history traits of the pests are outlined. The hemlock caterpillar (D. superans) overwinters in the soil in its larval stage: to control it, every tree stem was banded with vinyl tape to impede larvae crawling up to the canopy. For gypsy moth (L. dispar), predation of egg masses by birds was encouraged by pruning the lower branches of larch (L. leptolepis) and birch (B. platyphylla). none