A small yellow and black sawfly. In the female the abdomen is mainly yellow. The tegulae and the hind femora and tibiae are yellow, though the femora may be black basally. In the male, the mesepisternum and the pedicel and scape of the antennae are pale, as are the hind femora. The male antennae have 14 or 15 segments.
Eggs are deposited into the tip of willow leaf blades and the larvae create a blister mine.
Size: Female: 5 - 6mm, male: 3 - 5mm
Distribution: England, Scotland, Ireland
Flight period: Bivoltine, May to August
Plant associations: Salix spp. (willows)
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
Liston, A., Mutanen, M. and Viitasaari, M., 2019. On the taxonomy of Heterarthrus (Hymenoptera, Tenthredinidae), with a review of the West Palaearctic species. Journal of Hymenoptera Research, 72, p.83.