Wingspan 7-9 mm.
Distributed throughout mainland Britain, though rare in the southern half of Scotland and in Ireland, it can be common in places.
The larva feeds on alder (Alnus glutinosa), forming a small blotch mine on the underside of a leaf. Sometimes several larvae mine the same leaf.
The adults fly mostly in August, but the species may be bivoltine, with moths also recorded in May.
Leafmine (British Leaf Mining Fauna)