Length 6 to 8 mm. This is a bright orange-bodied sawfly with a black head, antennae and thorax. The legs are also orange and the wings have a dark stigma. Note that the side colour of the thorax is not diagnostic (it may be sexual dimorphism or simple variability).
There could be confusion with Brachythops flavens, but this usually has some yellow on the first antennal segments and also on the front of the thorax.
There are two UK species in this genus. Selandria melanosterna (formerly sixii) is very similar to sterna but larger (8 - 14mm), and less common. S. serva has the third antennal segment shorter than the three terminal segments combined, whereas in S. melanosterna the third segment is longer than the final three.
This species has a red ID rating and unless identified by a known expert you must provide a satisfactory explanation of how it was identified for the record to be accepted.
The larvae graze the leaves of various grasses and rushes.
Fairly frequent in Britain.
Locally common in Leicestershire and Rutland.
Leicestershire & Rutland Map
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Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015