About Chirosia betuleti (Ringdahl, 1935)
Chirosia betuleti (Ringdahl, 1935) is a species of fly that causes knotting gall in ferns. The galls develop in the terminal shoots of fern species, including broad buckler fern (Dryopteris dilatata), male fern (Dryopteris filix-mas), lady fern (Athyrium filix-mas), and ostrich fern (Matteuccia struthiopteris). Knotting gall caused by this fly has been recorded in numerous counties across the United Kingdom, as well as in the Netherlands, the Czech Republic, Denmark, Finland, France, Germany, Italy, Norway, Poland, northern and northwestern Russia, Slovakia, Spain, and Sweden.
