The
rose bedeguar gall,
Robin's pincushion gall, or
moss gall develops as a chemically induced distortion of an unopened leaf axillary or terminal buds, mostly on field rose (
Rosa arvensis) or dog rose (
Rosa canina) shrubs, caused by the parthenogenetic hymenopteran gall wasp (
Diplolepis rosae (Linnaeus, 1758)), previous synonyms are
D. bedeguaris,
Rhodites rosae or
Cynips rosae.
(Wikipedia)