Recorded widely across much of Britain, but very localised or easily overlooked. Most of the 33 records collated were older ones, with those post-1990 being from Kent, south Wales, the Peak District and Bristol, the latter involving a series from an urban park over at least a 16-year period (Musgrove, 2023).
Three predominantly black and white Pachyprotasis species in Britain and Ireland can cause confusion; rapae, variegata and simulans.
Females of variegata are readily distinguished through having a red hind femora and tibia but both rapae and simulans have black and white legs in both sexes. Pachyprotasis simulans has tergites with white apical margins conspicuously thickened on the mid-dorsal line. In rapae the apical margins are either not white on the median line, or are narrow and not thickened on the median line. The frons in simulans is shining with only faint coriaceous sculpture, whereas in variegata this sculpture is more noticeable between dense, shallow punctures.
Larvae feed on figworts, goldenrod and ragworts.
Size: 6.5 - 7.5mm
Distribution: England, Scotland, Wales
Flight period: May to June
Plant associations: Scrophularia spp., Solidago sp., and Senecio spp. (figworts, goldenrod and ragworts)
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
Musgrove, A.J. 2023. A review of the status of sawflies of Great Britain - Phase 2: The Athaliidae and the Tenthredinidae (excluding Nematinae). Natural England, unpublished