The common spangle gall wasp is a tiny wasp, Neuropterus quercusbaccarum, that causes a growth, or 'gall', on the underside of oak leaves in early autumn. It is common and widespread, and a single leaf can host up to 100 galls, each containing a single larva. The galls fall to the ground and can be seen around oak trees during autumn. The larvae continue to develop through the winter, and emerge as adults in April.
How to identify
The common spangle gall wasp produces a brown, disc-shaped gall on the undersides of oak leaves. You are more likely to see the galls than the adult gall wasps or the grubs. However, there are several similar, disc-shaped galls that grow on oak trees.
Did you know?
The common spangle gall wasp has two generations: the females that emerge in April from the previous autumn's oak-leaf galls, lay their eggs in oak catkins, creating hanging, round 'currant galls'. From June, a sexual generation emerge from the currant galls, ready to lay their eggs on oak leaves and start the cycle again.
