Wingspan c. 6mm.
The distribution of this species covers most of England and parts of Wales, and is relatively common, although it can be hard to find.
The larvae mine the leaves of sallow (Salix), especially S. caprea, initially mining the midrib of the leaf. Subsequently it mines into the leaf-blade, and tends to form a fairly distinctive blotch containing two lines of frass. It is quite a late feeder, mining from September into November.
Adults are on the wing in June, in a single generation. They are mostly blackish with a slight purple sheen and an obvious white or creamy blotch. The head is orange or yellowish.