Clustered Gall Wasp

Andricus brunneus, also known as the clustered gall wasp, is a species of oak gall wasp in the genus Andricus. It lives along the Pacific Coast of North America. Only females of this species are known. Adults are brown or reddish-brown and about 3 millimetres (0.12 in) long. It induces round galls on the leaves of white oaks, especially blue oaks. These galls are usually found in clusters, reddish to light brown, and about 6 millimetres (0.24 in) in diameter. Each holds a single larval chamber, from which adult females emerge in autumn.