Abdomen red with dark apex. At least the front legs with some red about the knees. Mesopleura with crater-like punctures in the middle. Entire mesonotum black. Female 8-9mm. Male 7-8mm.
Dolerus cothurnatus larvae feed on water and marsh horsetail.
Status: Locally common
Distribution: England, Scotland, Wales, Ireland
Flight period: May to July
Plant associations: Equisitum fluviatile and palustre (water horsetail and marsh horsetail)
Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London
Liston A, Knight G, Sheppard D, Broad G, Livermore L (2014) Checklist of British and Irish Hymenoptera - Sawflies, ‘Symphyta’. Biodiversity Data Journal 2: e1168. https://doi.org/10.3897/BDJ.2.e1168