Last modified: Feb. 19, 2021, 12:26 p.m.
A very rare and local species in Belgium.
The monophagous larva makes a leafmine, usually starting close to a lateral rib. It's a slender winding gallery with narrow linear black frass leaving clear margins from beginning till the end.
See also bladmineerders.be
Pupation in a pale brown cocoon.
The adults fly in two generations: May and June and again during August.
Especially on Alnus species. Occasionally also on Betula.