Mossy Rose Gall Wasp

Diplolepis rosae is a gall wasp which causes a gall known as the rose bedeguar gall, robin's pincushion, mossy rose gall, or simply moss gall. The gall develops as a chemically induced distortion of an unopened leaf axillary or terminal bud, mostly on field rose (Rosa arvensis) or dog rose (Rosa canina) shrubs. The female wasp lays up to 60 eggs within each leaf bud using her ovipositor. The grubs develop within the gall, and the wasps emerge in spring; the wasp is parthenogenetic with fewer than one percent being males.

A similar gall is caused by Diplolepis mayri, but this is much less common.