The only Tenthredo species where the whole body and hind legs are entirely black in both sexes. The head, including the clypeus, is also black, but the base of the mandibles is white. Although not mentioned in the literature, many specimens have a white fleck on the lateral face of the first tergite.
Tenthredo mandibularis larvae feed on coltsfoot and butterbur.
Size: 13 - 14mm
Distribution: England, Scotland, Wales
Flight period: June to August
Plant associations: Petasites hybridus (butterbur), Tussilago farfara (coltsfoot)
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]