Rhogogaster scalaris (nb naming follows Taeger and Viitasaari)
This species equates to Rhogogaster viridis in Benson's key.
Very similar to Rhogogaster chlorosoma. Generally this species is darker but there is crossover between lighter examples of scalaris and darker examples of chlorosoma. Males can be identified by the size of the plantar lobes (tarsal pulvilli) on the hind tarsi, however, in females there is overlap between the two species. In the male, the plantar lobe is about one-third the length of the next tarsal segment. In chlorosoma it is one-half the length.
The black marking on the top of the head is closed at the front to form a figure of eight. Usually the postocellar area is black with the black marks of the frons reaching to the occipital carina.
Rhogogaster scalaris larvae feed on a wide variety of trees and herbs.
Size: 10 - 13mm
Distribution: England, Scotland, Wales, Ireland
Flight period: May to July
Plant associations: Polyphagous Salix spp., Populus spp., Alnus spp., Betula spp., Epilobium spp., Quercus spp., Filipendula ulmaria, Vicia cracca. (various trees and herbs)
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
Taeger, A. and Viitasaari, M., 2015. European Rhogogaster s. str., with notes on several Asian species (Hymenoptera: Tenthredinidae). Zootaxa, 4013(3), pp.369-398.