Cimbex luteus - Willow Clubhorn
A large yellow and brown species very similar to Cimbex connatus. It is distributed widely but sparsely, in southern Britain with additional recent records from Ayrshire and the Moray Firth (Musgrove, 2022). Cimbex luteus has significantly more yellow on the body than connatus. In luteus the 3rd tergite has at most a narrow central dark mark and with much more extensive yellow on the underside of the abdomen. In luteus, the thorax is generally a lighter orange colour and the back of the head and scutellum are dulled by puncturation and denser hair.
Rarely, melanistic individuals are encountered where the background colour is near black with dark red markings on the thorax. These can easily be confused with Cimbex femoratus. However, the dark apical wing band is more defined in femoratus than in luteus and even in the darkest luteus individuals the tibiae are usually reddish.
Larvae feed on willows and poplars and in maturity are yellow rather than the yellow-green of connatus.
Size: 20 - 28mm
GB IUCN Status: Least Concern
GB Rarity Status: None
Distribution: England, Scotland, Wales
Flight period: May to July
Plant associations: Salix spp. (willows) including Salix alba (White Willow), Salix caprea (Goat Willow), Salix fragilis (Crack Willow), Salix viminalis (Common Osier) and Populus spp. (poplars).
Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London
Bibolini, C. 1967: Contributo alla conoszenca des Cimbicidi Italiani (Hym. - Symphyta). I. La Cimbex lutea L. Biologia ed esame corologico e bibliografico. - Frustula Entomologica, La Spezia 8: 1-215
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
Muche, W. H. 1962: Die Larven unserer Blattwespen (9) (Hymenoptera: Tenthredinoidea; Cimbicidae). - Entomologische Nachrichten, Dresden 6(12): 127
Musgrove, A.J. 2022. A review of the status of sawflies of Great Britain - Phase 1: families other than Tenthredinidae. Natural England, unpublished