Cephus nigrinus - Wood Stem-sawfly
Quite widespread as far north as Yorkshire, although decidedly local in eastern areas, the south-west and much of Wales (Musgrove, 2022). Easily recognised as the only Cephus species with an all black abdomen, although occasionally British specimens have yellow flecks on the lateral margins of some tergites. The sawsheath is set in a straight line with the oblong plate. Cephus nigrinus appears to be a woodland species in the Britain.
Larvae feed by boring into Smooth Meadow-grass.
Size: 7 - 10mm
GB IUCN Status: Least Concern
GB Rarity Status: None
Distribution: England, Wales
Flight period: May to July
Plant associations: Poa pratensis (Smooth Meadow-grass)
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. 2022. A review of the status of sawflies of Great Britain - Phase 1: families other than Tenthredinidae. Natural England, unpublished