Hydraecia medialis is a moth in the Noctuidae family. It is found in western North America. East of the Cascades, it occurs as far north as the Cariboo region in south-central British Columbia. The range extends across the Rocky Mountains in Montana and then spreads north and south on the Great Plains to reach Alberta, the western Dakotas and northern New Mexico. The habitat consists of open ponderosa pine forests, drier sagebrush steppe and juniper woodlands. The larvae probably bore into the stems and roots of Lupinus species.