Euura bergmanni (formerly Nematus bergmanni)
Females are similar to Euura sylvestris and the oligospila group though the head is more rectangular in dorsal view. Specimens need to be determined by reference to the saw or penis valve. The background colour is usually green in life but may be yellow on occasion. The female is very variable in the amount of black on the body with spring and northern specimens sometimes almost entirely black on the thorax and abdomen. The summer generations exhibit more green colouration. In the summer generation females there is often an anchor-shaped dark mark on the otherwise green scutellum but the scutellum may be entirely green. The ocelli are black but the area posterior to the ocelli is predominantly green often with a black longitudinal line central to the postocellar area.
The male has the mesopleura mostly pale and the inner eye orbits are yellow or white. The malar gap is 1 to 1.4 times the diameter of the front ocellus.
Euura bergmanni larvae are slender and green with a white dorsal stripe, a pale head with a vertical brown stripe through each eye. They feed on various willows. Summer generations develop rapidly and spin a silken cocoon in leaf axils and growing tips. They remain in the cocoon for as little as one week.
Size: Female: 6 - 8mm. Male: 5 - 6mm.
Distribution: England, Scotland, Wales, Ireland
Flight period: Multivoltine, April to September
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
Prous, M., Liston, A., Mutanen, M. 2021. Revision of the West Palaearctic Euura bergmanni and oligospila groups (Hymenoptera, Tenthredinidae. Journal of Hymenoptera Research. http://zoobank.org/1459B177-AF2B-4D39-9483-E8BA21E70E67