Eutomostethus ephippium

5-7mm. This sawfly is black with a bright red thorax. It also has black femora (thighs) and then paler legs. It is sometimes referred to as the Lawn Sawfly but this isn't a widespread name.

Grassy places

It flies from May

Larvae feed on grasses of the Poa family.

Fairly frequent especially in southern Britain

Common in Leicestershire and Rutland.