not so common species in Belgium, seems to be spread out lately.
larva makes a large mine with one strong longitudinal fold on the
underside of narrow-leaved willows like Salix alba, S. babylonica and
rarely on S.
It's also known from Populus,
but this happens occasionally. Pupation in the larval feeding place.
The pupa hibernates.
adults fly in two generations a year: in April-May and again in
Liège, Angleur, 28 August 2010.
(Photo © Jean-Yves Baugnée)