An uncommon and local species in Belgium.

The first generation larva lives in the stem, usually in the flowering part of Epilobium angustifolium, causing a gall or swelling, those of the second generation lives in a seedpod. 

The adults fly in two generations a year; from July till August, and again from September onwards till May after hibernation. They come to light

lID: very similar to M. subbistrigella, from which it's distinguished by its larger size and by the presence of distinct white costal streaks in the apical area.