Robin’s Pincushion – Diplolepis rosae

Diplolepis rosae (Linnaeus, 1758)

Size up to 7 cm across.

This strange yet beautiful growth is the result of a tiny gall wasp called Diplolepis rosae laying its eggs in a wild rose bud in springtime. Also called the ‘Bedeguar Gall Wasp’, the females appear in the spring just in time to lay their eggs in the fresh young buds. Males are a rarity, and most females lay fertilised eggs without mating.

The gall mainly grows on the stem of the plant. The gall has a woody core each surrounded by branching red or green hairs. The core usually has multiple chambers in which each a wasp larvae develops. The galls turn brown in the autumn and lose many of their hairs.