The Langmaid's Yellow Underwing (Noctua janthina) is a species of moth in the Noctuidae family.
Very similar to the Lesser Broad-bordered Yellow Underwing (N. janthe), the Langmaid's Yellow Underwing has only slight differences. One is the the border on the hindwing is more bold, and the Langmaid's is generally darker, but that can't cause positive identification. Dissection of the genitilia may be needed for a confident identification. This species flies in July and August.