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The gall wasp has 2 generations per year. One being sexual and the other agamic (all female, and needs no male to reproduce). The sexual generation causes current galls in catkins and singles below leaf with a red mark above. Whereas the agamic generation causes Common spangle galls on the underside of oak leaves. The agamic generation was previously named N. lenticularis before it was realized to be two generations of the same species.
The female wasp is winged and about 2.5-3mm in length. Its head is a very dark, shiny brown with large and long bright pale brown eyes. The antennae are yellow brown and comprise of 15 segments with a yellow scape and pedicel.
The thorax is again a very dark shiny brown with straw coloured tegulae. The wings are very long, clear with dark brown veins. The legs are semi translucent yellow with sparse pale hairs.
The Gaster or abdomen is again very dark brown, blocky and segmented with a particularly jagged appearance to the edge. The petiole is very short and tiny.
Flying time - May to july
The male wasp is winged and slightly longer than the female, but thinner and ranges from 2.3-3.2mm in length. The head is small and dark brown with large dark brown eyes, which have a conspicuous pale circumference. The antennae comprise of 15 segments and are pale brassy in colour.
The thorax, as in the female, is a shiny very dark brown with straw coloured tegulae, and the wings are clear and long with dark brown veins. The legs are translucent straw coloured with a brown top to the coxae.
The gaster is thin and glossy dark brown with a thin, long petiole.
Common Inquiline species found in N. quercusbaccarum current galls include; Synergus albipes, S. apicalis, S. gallaepomiformis, S. nervosus and S. thaumacerus
Common hyperparasites of N. quercusbaccarum current galls include; Aulogymnus arsames, A. gallarum, Eupelmus urozonus, Eurytoma brunniventris,
Mesopolobus sericeus, M. tibialis, Torymus auratus (=nitens) and T. flavipes.
is abundant on the underside of the oak leaf and can reach 5mm across. This gall holds the agamic generation and looks like a rimless disc with a rising central mound. It is usually yellow in colour but can sometimes appear more greeny yellow. There are often also red hairs. It is a single cell gall holding one wasp and can be seen from July onwards, until the leaves fall in autumn. The wasp larva will mature in august but remain in the gall on the ground throughout the winter, emerging the following year from january to may.
The agamic generation wasp is winged and measures in at 2.1-3.1mm in length. The head is small, black and bent down sharply giving it a hunched appearance, with mid sized black eyes. The antennae are dark to dark brassy with a dirty yellow scape and pedicel, with 15 OR 16 segments.
The black, smooth thorax has brown and gold tegulae. The long clear wings have thick brown viens and fairly dense brown hairs. The dark brown hairy legs blend into yellow joints.
The large black gaster is moderatly glossy and blends into a yellow brown ventral spine. It is evenly segmented.
Flying time - January to may.
Common Inquiline species found in N. quercusbaccarum common spangle galls include; Synergus albipes, and S. nervosus
Common hyperparasites of N. quercusbaccarum common spangle galls include; Aulogymnus gallarum, A. gallarum f. pulchra, Eurytoma brunniventris, Mesopolobus dubious, M. fasciiventris, M. tibialis, Pediobius clita, P. lysis and Torymus flavipes.
More detailed descriptions and identification keys are available from Robin Williams at the British Plant Gall Society.
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