This is a very localised subspecies of dumetata, a species whose nominate form occurs in central and southern Europe: hibernica represents a relic population, presumably left behind after the retreat of the Ice Age, found only in the Burren area of County Clare, Ireland where it was first discovered in 1991.
Wingspan c. 26mm. The adult moths fly in August and are attracted to light. They can also be found visiting the foodplant and other flowers after dusk. The larval foodplant is buckthorn (Rhamnus catharticus).