A larger species. One of five species that have white bands on the antennae. This species has black setiform antennae with the white confined to segments six to eight. In females the abdomen is entirely black, but in males this is tinged brown. The stigma is yellowish-brown and unicolorous and the tegulae are black. In common with Tenthredo colon, the mesopleura and first tergite are flecked with white but in addition fagi has a scutellum marked as a white hemisphere.
Larvae feed on a range of foodplants including hazel and mountain ash.
Size: 11 - 15mm
Distribution: England, Scotland
Flight period: May to July
Plant associations: Corylus avellana (hazel) and Sorbus aucuparia (mountain ash)
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
Fekete, K. (2018) Beginner’s guide to identifying British Tenthredo, Natural History Museum, London. http://www.nhm.ac.uk/content/dam/nhmwww/take-part/identification-trainers/sawflies-guide-id-trainees.pdf [Accessed 26Apr2019]