Cephus pygmeus - Wheat Stem-sawfly
Common and sometimes abundant throughout much of England south-east of a line between the Tees and the Severn. More sparsely distributed in Wales and south-west England, and no records from Scotland to date (Musgrove, 2022).
Adults visit yellow flowers especially composites (dandilion, etc.) and buttercups. Very similar to Cephus spinipes. Cephus pygmeus has bifid claws where the teeth are virtually parallel, whereas spinipes has claws where the inner tooth is erect and distant from the end tooth. In females the sawsheath is set in a direct line with the oblong plate, whereas in spinipes the sawsheath is set at an angle to the oblong plate. Also, in female pygmeus the hind tibia is extensively black, whereas in spinipes only the apex is black. The abdomen is marked with yellow bands on at least tergites 4 to 6.
Larvae feed inside the stems of grass.
Size: 5 - 10mm.
GB IUCN Status: Least Concern
GB Rarity Status: None
Distribution: England, Wales
Flight period: May to July
Plant associations: Larvae on cereal crops and grasses including Agropyron spp. (couches), Avena spp. (oats), Bromus spp. (bromes), Hordeum spp. (barleys), Phleum spp. (timothy grasses), Secale spp. (ryes), and Triticum spp. (wheats).
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
Lorenz, H. and Kraus M. Die Larvalsystematik der Blattwespen (Tenthredinoidea und Megalodontoidea). - Abhandlungen zur Larvalsystematik der Insekten No. 1. Berlin: Akadamie - Verlag; 1957.
Musgrove, A.J. 2022. A review of the status of sawflies of Great Britain - Phase 1: families other than Tenthredinidae. Natural England, unpublished