Last modified: March 15, 2023, 5:20 p.m.
Recorded for the first time in Belgium in 2012 at Ename (OV). This species can be confused with either Mompha divisella or Mompha jurassicella which also live on Epilobium hirsutum and which are very similar externally. A very rare species.
Wingspan is about 10 mm.
A white, somewhat sticky cocoon, the channel to the exit hole is lined with white silk. Pupa shining pale brown.
The larva lives inside the stem causing a spindle-shaped gall, up to 15 mm long and 4 mm broad, mainly in the top- and side-stalks, preferably in a flowering side-stalk.
Before pupation an exit hole is made in the lower part of the gall, leaving only a thin layer of bark. The pupa lies with its head downwards in the cocoon.
The species hibernates in the adult stage.
One generation a year: from mid-July till mid-September, and after hiberation till the end of May.
Monophagous on Epilobium hirsutum.
Mainly in damp situations like marshes, roadside ditches, but also in drier habitats.