Oak gall wasps

Symtpoms
Odd structures develop on the foliage, buds, acorns and other parts of an oak tree, mainly in late summer but sometimes also in the spring.

Spot them
More than 30 species of gall wasps occur in Britain on the common oak, Quercus robur. Each species lays its eggs in a particular structure on the tree - the roots, bark, buds, leaves, catkins or acorns. The grubs feed on a nutritious layer of cells within the galls, where they eventually pupate and turn into adult wasps.