A distinctive species with a blood red top to the thorax and heavily punctured sides and head. Similar to Eutomostethus ephippium but much larger and much more duller due to the punctures. Males are extremely rare. Mid and hind tibia whitish about the knees.
Larvae are white with a waxy coat and feed ob alder.
Size: 5 - 7mm
Distribution: England, Scotland, Wales, Ireland
Flight period: Univoltine May to August
Plant associations: Alnus glutinosa (alder)
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