Sirex juvencus - Bull Woodwasp

Recorded widely throughout England (except the south-west) and Wales. Benson (1951) felt that it was possible this species was indigenous to Caledonian pine forests but there is currently only a single Scottish record from Fife in 1947 (Musgrove, 2022).

Females have reddish to yellow legs including the apical tarsal segments of all legs. The head and thorax are blue-black and the abdomen is dark brown. Basal antennal segments are often reddish brown with the remainder black.

Males are similar to the female but are banded in yellow on middle tergites and always with basal antennal segments reddish brown. Hind legs in the male are darker but with the apical tarsal segments still pale.

Benson notes that forms with entirely black antennae maybe confined to Scotland in Britain. Viitasaari and Midtgaard(1989) make the comment that these forms may in fact be the species Sirex atricornis. It would be necessary to re-examine any such Sirex specimens from Scotland, before it is confirmed as a British species (Musgrove, 2022).

Sirex juvencus larvae feed in timber of conifers for up to 3 years.

Jump to other Sirex species

Size: 10 - 40mm

GB IUCN Status: Least Concern
GB Rarity Status: None

Distribution: England, Scotland, Wales, Ireland

Flight period: June to October

Plant associations: Pinaceae spp., mainly Picea spp. (firs, larches, spruces and pines) including Pinus sylvestris (Scots Pine), Picea abies (Norway spruce), Pseudotsuga spp. (Firs).


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.

Liston, A. D. 1995: Compendium of European Sawflies. List of species, modern nomenclature, distribution, foodplants, identification literature. - Gottfrieding, Chalastos Forestry : 1-190

Musgrove, A.J. 2022. A review of the status of sawflies of Great Britain - Phase 1: families other than Tenthredinidae. Natural England, unpublished

Schiff, N.M., Goulet, H., Smith, D.R., Boudreault, C., Wilson, A.D. and Scheffler, B.E., 2012. Siricidae (Hymenoptera: Symphyta: Siricoidea) of the western hemisphere. Canadian Journal of Arthropod Identification 21: 1-305, 21, pp.1-305.

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