Last modified: Nov. 23, 2023, 10:45 a.m.
A very rare species in Belgium.
Wingspan 15–16 mm.
The larva lives in a low part of the hollow stem, causing a clear swelling. The larva closes the space above by making out of silk and frass a few septums. Pupation in the stem.
Adults are on the wing in two generations a year, which can hardly be separated, from late April till early August.
It inhabits marshes, riverbanks etc...