This species has been recorded extremely rarely over the years, mostly from Yorkshire southwards although Benson (1952) noted an occurrence north to Roxburghshire. Since 1990 at time of writing it has only been recorded twice, from Surrey in 1993 and Worcestershire in 2006 (Musgrove, 2023).
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.
Tenthredo fagi larvae feed on a range of foodplants including hazel and mountain ash.
Size: 11 - 15mm
GB IUCN Status: Critically Endangered
GB Rarity Status: Nationally Rare
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
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]
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
Musgrove, A.J. 2023. A review of the status of sawflies of Great Britain - Phase 2: The Athaliidae and the Tenthredinidae (excluding Nematinae). Natural England, unpublished