A no-choice feeding study was used to evaluate larch casebearer development and survival on eight species of conifer seedlings and two foliar stages of larch from molting to the fourth-instar larvae through adult eclosion. Percentage survival through adult eclosion varied on foliage of western larch (spring—flush stage, 44%; fall—bud set stage, 23%), Douglas-fir (40%), grand fir (26%), Englemann spruce (26%), western white pine (10%), and lodgepole pine (6%). No survival occurred on ponderosa pine or western hemlock. The rate of development differed among conifer seedling species, and between foliar stages of larch.