Fern-parasite
Guides
Chirosia betuleti
Knotting Gall
Chirosia betuleti is a gall-forming fly in the family Anthomyiidae that induces characteristic knotting galls on fern fronds. The species is best known through the distinctive damage it causes rather than adult morphology. It has been recorded across much of Europe, with extensive documentation in the United Kingdom. The gall structure and larval mining behavior are well-studied, though adult fly biology remains less documented.