Last modified: June 24, 2021, 1:57 p.m.
A very rare and local species in Belgium, only known from some dispersed localities in Flanders.
At first a rather short, straight gallery, soon widening into an elongated blotch. Unlike the other Cosmopterix species which mine into Phragmites it does not construct a silken tube for shelter and hence, the larva is visible through the mine. Several larvae sometimes mine the same leaf.
See also bladmineerders.be
The species hibernates in the larval stage, inside the mine.
Pupation in the mine in springtime.
The adults fly around the food plant at dusk and later come to light.
One generation a year: from the end of May till mid-October.
Monophagous on Phragmites australis.
Most types of habitat where the foodplant grows, with a preference for large reed beds in both fresh and brackish water.