Palaeosia is a monotypic moth genus in the family Erebidae erected by George Hampson in 1900.

Its only species, Palaeosia bicosta, the two-ribbed arctiid or two-ribbed footman, was first described by Francis Walker in 1854.

It is found in south-eastern Australia.

The larvae feed on lichen.

This Lithosiina-related article is a stub.