Last modified: Feb. 18, 2020, 9:20 a.m.
A common species in Belgium.
Initially a narrow gallery filled with green frass, later the pattern of frass changes abruptly in linear black frass, leaving broad clear margins while the corridor hardly widens.
See also bladmineerders.be
The adults fly in one generation a year during May and June.
The monophagous larva makes a leafmine on Betula.