Wingspan c.12 mm.
This rather colourful species is distributed fairly commonly in much of England and Wales, and in some parts of Ireland.
The adults fly during June to August, and can be attracted to light. Although superficially similar to other Caryocolum species, the blackish triangular mark near the base of the costa is generally diagnostic.
The larvae feed on greater stitchwort (Stellaria holostea) in Britain, initally mining the leaves in a gallery and later between spun shoots.