Endothenia lapideana (Herrich-Schäffer, 1851)
Digitalis lutea, Belgium, prov. Namur, Viroinval, 7.iii.2018 © Ruben Meert: host plant in early spring
The stump of the broken old stem has been closed with silk.
The larva bores in the stem.
distribution within Europe
Lepiforum. (There also more pictures)