Cosmia diffinis, the white-spotted pinion, is a moth of the family Noctuidae The species was first described by Carl Linnaeus in 1767. It is found in central and southern Europe, to the north it is found up to central England and the southern parts of the Netherlands. There is a disjunct population in Gotland. To the south, it is found down to Spain, Italy, Russia, northern Greece and Bulgaria. In the east, it is found as far as Lithuania and the Black Sea.