Small (2-5mm) dark wasps. ~35 UK species

Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and identifying characters.

Tetramesa species feed on plant tissues. They are host-specific and primarily associated with grasses, where they typically act as gall inducers or stem borers. Adults feed on nectar. 

Widespread.

Unknown.