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)

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.

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Andricus quercuscalicis (Burgsdorf, 1783)

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.

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Cynips divisa (Hartig, 1843)

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

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Diplolepis nervosa (Curtis, 1838)

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.

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Diplolepis rosae (Linnaeus, 1758)

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

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Neuroterus numismalis (Geoffroy in Fourcroy, 1785)

Neuroterus quercusbaccarum (Linnaeus, 1758)

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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