Length up to 30 mm. The asexual generation of the Artichoke Gall Wasp (Andricus foecundatrix) is responsible for causing these galls which grow from Pedunculate Oak (Quercus robur) or Sessile Oak (Quercus petraea) leaf buds. Also called the Hop Gall, a single larva develops within the gall to maturity in August, when it falls from the tree for pupation to take place during the winter. In spring the adult wasps emerge to lay eggs in oak catkins, from which the sexual generation will eventually emerge.
Seen in mid-summer through to August. Common and widespread throughout Britain where oak is present.
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps & Sawflies)
Family Cynipidae (Gall Wasps)
Species Andricus foecundatrix (Hartig, 1840)
Photos: Local wood, South Staffordshire. July 2020 & July 2021. © Peter Hillman