Out of The Ordinary

Robin’s Pincushion (Diplolepis rosae) – Also called the Bedeguar Gall, this strange but beautiful, almost alien, fibrous growth is caused by the larvae of a tiny wasp. It is found on the stems of wild roses, and each of these can contain many grubs which feed on the plant tissues inside a woody heart filled with chambers, but apparently do the plant no serious harm.

I am fascinated by plant galls, which often go unnoticed, and how organisms like wasps, flies, mites and even fungi, can transform living tissue into these abnormal, often bizzare forms.

Robin's Pincushion Diplolepis rosae

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Robin’s Pincushion

Diplolepis rosae

Robin's Pincushion (Diplolepis rosae)

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, and it can spread up to 7cm across. 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.

Photograph of Robin’s Pincushion (Diplolepis rosae), taken August 2010, country park, Staffordshire. © Pete Hillman 2010. Camera used Panasonic Lumix DMC-FZ38.