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ROBIN'S PINCUSHION

ROSE BEDEGUAR GALL

Diplolepis rosae

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typeZglobed

West Lancs Golf Course, Hall Rd, Sefton Coast. Photo: © RWD
Growing on Rose bushes, possibly Field Rose. Field Rose and Dog Rose are the preferred hosts.


West Lancs Golf Course, Hall Rd, Sefton Coast. Photo: © RWD
Photos taken before the golf course commandeered most of the path these was on, and several dunes as well, by enclosing it with a tall nasty green metal fence! All your Author can say is 'Golf Balls!'. Many white demarcation posts, such as the one in the foreground, are quite possibly now well within the fence.


West Lancs Golf Course, Hall Rd, Sefton Coast. Photo: © RWD
The galls grow mainly on the stem (sometimes smaller ones on the leaves) and are caused by the gall wasp Diplolepsis rosae. They are variously coloured pale green, pale orange, through to orange and red and up to 7cm across.


West Lancs Golf Course, Hall Rd, Sefton Coast. Photo: © RWD
In the centre is a woody core around which numerous feather-branched tapering 'hairs' proliferate, which are


West Lancs Golf Course, Hall Rd, Sefton Coast. Photo: © RWD
The pathenogenetic (they are virgin births) hymenopteran gall wasp Diplolepsis rosae lays eggs in the flower buds in spring. After hatching the larvae feed on the leaves or the buds and a week later chemically induce the plant to grow abnormally with many branched hairs. The woody core contains numerous chambers (up to 60) where each wasp larvae develop. The larvae moult about 5 times before going into the pupal stage in October. The pupae over-winter inside the gall, only finally start emerging in the following February or March continuing until August. Thus there are still developing pupae in the above examples. There may be up to 60 in any one gall, of which <1% are males, the rest female. Male wasps are 3mm long and black with bicoloured legs whilst the females are 4mm long and have yellow-red abdomens and bodies, the rest being black. Only the females will go on to repeat the cycle by laying parthogenetically-derived (without sex) eggs into another host plant. The hairs eventually drop off in August leaving the woody core still attached.


West Lancs Golf Course, Hall Rd, Sefton Coast. Photo: © RWD
The 'hairs' taper and are branched.


16th Sept 2009, Crag Foot, Warton Crag, Lancs. Photo: © RWD
A dark-red specimen and the very first Robins Pincushion espied by your Author.


The Genus Dipolepis should not be confused with that of several (non-native) plants with identical genera name. The one referred to here is that of a wasp, not of non-native plants from the Chili and/or Argentina area which belong to the Apocyanaceae family, some of which do indeed grow in the UK (in the Vinca Genus). After the gall has been vacated a wide range of other organisms can inhabit the gall, such as 'inquilines' which are opportunistic squatters. Other parasites lay their eggs inside the developing wasp larvae. Hyperparasites can even parasitize the parasites. There could be a lot going on inside a Bedeguar gall.

Easily mistaken for : an unusual 'flower'.

Uniquely identifiable characteristics

Distinguishing Feature :

No relation to : Ragged-Robin (Silene flos-cuculi), Little Robin (Geranium purpureum) nor Robin's Plantain (Erigeron philadelphicus) [plants with similar names].


  Diplolepis rosae  ⇐ Global Aspect ⇒   

Distribution

 BSBI maps

ROBIN'S PINCUSHION

ROSE BEDEGUAR GALL

Diplolepis rosae