Width up to 2-4 mm. Each of these small disc-like galls, which are yellow-green but appears reddish due to red or violet hairs, contain the agamic larva of the wasp (Neuroterus tricolor). They occur on the underside of oak (Quercus) leaves. These are the only spangles which appear on lammas leaves (2nd crop of leaves). During autumn when the leaves fall the larva mature throughout the winter within the galls. The adults emerge in spring and lay eggs in young oak leaves for the sexual generation to develop in hairy, spherical galls. Similar to the Common Spangle Gall (Neuroterus quercusbaccarum) which is larger and flatter with a raised central dome or ‘pimple’.
Seen from July to September. Found wherever oak (Quercus) grows. Occasional in Britain.
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps & Sawflies)
Family Cynipidae (Gall Wasps)
Species Neuroterus tricolor (Hartig, 1841)
Photos: Local wood, South Staffordshire July 2020. © Peter Hillman