One of the black species. Arge expansa is thought to be a cooler climate species and is more likely to be encountered in north and central Scotland and Ireland. Females can be separated from Arge fuscipes by a pale costa and subcosta (dark in fuscipes) and in males the hind tibia are white at the base (entirely black in fuscipes).
Distribution: Scotland, Ireland
Flight period: June to July
Plant associations: Betula spp. and Salix spp. (birches and 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