Psammopolia arietis is a moth of the family Noctuidae.

It occurs on Pacific Coast sand beaches from Mendocino, California to south-western Alaska.

It is absent from the inland Strait of Georgia.

[1] Adults are on wing from late July to early September.

The larvae live in sand dunes and feed on Lathyrus littoralis, Polygonum paronychia, Abronia latifolia and an unspecified grass.