Wingspan 23-28 mm.
The diagnostic zigzag lines and bands of dark and pale colour make this species easy to identify.
A rather local species, occurring in the southern half of Britain, chiefly among ash (Fraxinus), the foodplant. The larvae burrow into the bark of ash trees, and can eventually kill the tree if present in numbers.
The adults are on the wing in July and August, and are attracted to light after dark.