Wingspan 4-5 mm.
A species which is spreading north and west since its discovery in Hampshire in 1914. It has now extended its range to Yorkshire, though it is still scarce in the north.
The larvae mine the leaves of sycamore (Acer pseudoplatanus) during July and August, and in September and October The initial mine is slender with narrow black frass. The frass in the later part of the mine can be neatly scattered, or remain a narrow central line.
The adults have bronzy wings tinged with purple and a narrow silvery fascia. They are on the wing in May and August.