A fairly common species in Belgium.

The amber yellow larva makes a leafmine usually starting close to  the midrib or near the leaf edge on the upper or underside side of small-leaved willows like Salix alba, S. babylonica, S. fragilis, S. pentandra and S. viminalis.  Pupates in a dark reddish brown cocoon covered with fluffy silk.

The adults fly in two generations a year; during May and June and again in September. 

ID mine: starts as narrow gallery, almost completely filled with black frass. It soons widens and frass is lying broken linear leaving clear margins. Finally it expands into a small blotch which regurarly absorbs the earlier gallery.