This is a species of Central European origin and is not thought to be the same species at S. cyaneus. Sirex torvus females have the sawsheath longer than the basal plate (as described in Benson) whereas S. cyaneus has the sawsheath equal in length to the basal plate.
The female is blue-black with reddish yellow legs and is similar to S. juvencus. However, the basal segments of the antennae are always black.
Males differ from the female in having darker hind legs and an abdomen that is reddish brown from tergite 3 to the apex.
Larvae feed in the timber of fir trees for up to 3 years.
Size: 10 - 40mm
Distribution: England, Scotland, Wales, Ireland
Flight period: June to October
Plant associations: Abies spp. (firs)
The National Biodiversity Network records are shown on the map below. (See terms and conditions)
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
Schiff, N. M., Valley, S. A., LaBonte, J. R. and Smith, D. R. (2006) 'Guide to the siricid woodwasps of North America.' Forest Service, Forest Health Technology Enterprise Team. USDA, Morgantown
Viitasaari, M. & Midtgaard, F. 1989: A contribution to the taxonomy of horntails with notes on the genus Sirex Linnaeus (Hymenoptera, Siricidae). - Annales Entomologici Fennici, Helsinki 55(3): 103-110