The buff ermine (Spilarctia luteum) is a moth of the family Arctiidae. It is sometimes placed in the genus Spilosoma. The wings of this species are buffish yellow (the males tend to be more yellow in colour than the females) and are typically marked with a diagonal row of dark spots on the forewing and a few other scattered spots on both forewings and hindwings. The extent of black markings varies considerably, however, from almost spotless examples to largely black melanic forms. The wingspan is 34-42 mm. The species flies from May to July The larva is pale brown and very hairy. It is polyphagous, feeding on a wide variety of trees, shrubs and herbaceous plants. This species overwinters as a pupa.
It is found throughout the temperate belt of the Palearctic region south to northern Turkey, Georgia, Kazakhstan, southern Siberia (excluding Buryatia), Eastern Mongolia, Amur Region, China, Korea and Japan.