Robin's Pincushion

Diplolepus Rosea is a gall wasp which causes a gall known as the Rose Bedegoar Gall, Robin's Pincushion or Mossy Rose Gall., usually on Field or Dog Roses.
The female wasp lays up to 60 eggs within a leaf bud, grubs develop within the gall and wasps emerge in Spring.   Fewer than 1% are male.