The adult is black throughout.

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.

Any habitat where Juncus species are present in numbers.

Adult early May to early July

Larva is rather distinctive with a yellowy green body and an orange head. It has a creamy coloured 'skirt' with a row of black dots. It is associated with various Juncus species of Rush.

Can be fairly frequent, but quite local in distribution. Most British records come from England.

Locally frequent in Leicestershire and Rutland.

https://www.sawflies.org.uk/dolerus-achaetoprion-ferrugatus/