Length 1.5 to 2mm. The male wasp is very dark brown to black on the head has a hunched thorax, with a black abdomen. The legs are yellowy brown and the antennae are a translucent yellow/brown colour. The female has a dark brown appearance overall.

[Note that parasitoids and inquilines may also emerge from galls]

There are many similar species of gall-wasp.

We recommend that the gall-causer is verified by an expert before submitting to NatureSpot - take good photographs, note the host gall and emergence date, and retain a specimen

Marble galls on oak

Adult females exit Oak Marble Galls from August to October.

Common throughout Britain.

Common