Platyprepia is a genus of tiger moths in the family Erebidae. It contains only one species, Platyprepia virginalis, Ranchman's tiger moth, which is found in western North America, ranging from southern Monterrey Bay in California across Nevada and southern Utah to Colorado and north to southern British Columbia. The habitat consists of wet lowland prairies, wet meadows, wet forests and in riparian zones along creeks in dry desert regions.