The wingspan is 35–38 mm. The length of the forewings is 16–20 mm. Has no pale grey tints; the red-brown ground colour varying only to dark grey; the claviform (club-shaped) stigma is produced as a dark dash to outer line; upper stigmata pale with partial black outlines, a black basal streak with pale patch above it; hindwing pale fuscous, paler at base; the form achates Hbn. has the forewing uniform red brown; while humeralis Haw. is fuscous grey with the red tints absent; ab. nigrifusa nov. [Warren] is wholly suffused with black, the orbicular stigma and traces of outer and submarginal lines remaining pale grey.Seitz, A. Ed., 1914 Die Großschmetterlinge der Erde, Verlag Alfred Kernen, Stuttgart Band 3: Abt. 1, Die Großschmetterlinge des palaearktischen Faunengebietes, Die palaearktischen eulenartigen Nachtfalter, 1914
