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Gall wasps Cynipidae are themselves small, unremarkable and difficult to identify. The larvae live within galls which they induce on various plants, oak being a great favourite. A common pattern is for an alternation of 2 generation each year, one sexual and one parthenogenic, producing different types of gall (even on different plant species).

Andricus kollari (Hartig, 1843)

Andricus kollari
  • A Marble Gall on the stem of Quercus robur.
  • The larvae causing these in summer are asexual. The adults lay eggs on Turkey Oak Q. cerris which form smaller galls containing a sexual generation.
  • The adults from the marble galls may emerge in Autum as here, completing two generations in a year; or in spring thus taking two years to complete the cycle - this is more common in northern Britain.
  • These galls have spread from southwestern Britain since introduction in the 19th century.
  • This gall is about 18mm diameter. A complex collection of inquilines and parasitoids may develop within.
  • Cambridge TL464614, 29 Aug 2002.

Andricus quercuscalicis (Burgsdorf, 1783)

Andricus quercuscalicis
  • These growths on the acorns of Quercus robur are called Knopper Galls.
  • The larvae causing these in summer are asexual. Adults emerge in spring to produce a new sexual generation on the catkins of Q. cerris (itself an invasive non-native species).
  • These galls have rapidly become widespread in Britain since they first appeared about 1960.
  • Single galls are about 22mm across.
  • Cambridge TL464614, 21 Aug 2002.

Cynips divisa (Hartig, 1843)

Cynips divisa
  • Two Currant Galls on the underside of a leaf Quercus robur.
  • These galls are about 2mm diameter.
  • Cambridge TL464614, 29 Aug 2002.

Diplolepis nervosa (Curtis, 1838)

Diplolepis nervosa
  • These are known as Spiked pea galls - somebody must have worked for weeks on some of these names :-)
  • A selection of galls from nearby rose bushes.
  • Pupae overwinter in the fallen leaf-galls, adults emerge in spring.
  • Up to about 6mm across (tip to tip).
  • Cambridge TL463614, 11 Sep 2002.

Diplolepis rosae (Linnaeus, 1758)

Diplolepis rosae
  • This growth on a wild rose is called a Bedeguar Gall, or more picturesquely a Robin's pincushion. (Bedeguar comes from a French, and ultimately a Persian, word meaning 'wind-brought').
  • Several D. rosae larvae form the gall, and they may been joined by the harmless inquiline cynipid Periclistus brandtii (Ratzeburg) and (as in marble galls) a complex ecology of parasitoids and hyperparasitoids.
  • The species consists almost exclusively of parthenogenic females.
  • This example is about 7cm in diameter.
  • Cambridge TL463614, 18 Jul 2002.
  • Synonym: Rhodites rosae

Neuroterus numismalis (Geoffroy in Fourcroy, 1785)

Neuroterus quercusbaccarum (Linnaeus, 1758)

Neuroterus numismalis and N. quercusbaccarum
  • Under a leaf of the same long-suffering Quercus robur as the Knopper Galls are these two types of spangle galls:
  • The flat Common Spangle Galls of N. quercusbaccarum. up to 5mm diameter
  • The cupped Silk Button Spangle Galls of N. numismalis. about 2mm diameter
  • Again these are an asexual generation: the sexual generation of N. quercusbaccarum form currant galls on young leaves and catkins in spring, in this case still on Q. robur; those of of N. numismalis are inconspicuous leaf galls.
  • Cambridge TL464614, 2 Sep 2002.

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