Sirex juvencus

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.

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

Jump to other Sirex species

Size: 10 - 40mm

Status: Common

Distribution: England, Scotland, Wales, Ireland

Flight period: June to October

Plant associations: Pinaceae spp., mainly Picea spp. (5) (firs, larches, spruces and pines) incl...

Pinus sylvestris (Scots pine) (5)
Picea abies (Norway spruce) (4)
Pseudotsuga spp. (Firs) (3)


1. Benson, R.B., 1952. Handbooks for the Identification of British Insects. Hymenoptera, Symphyta, Vol 6, Section 2(a-c), Royal Entomological Society, London

2. Liston A, Knight G, Sheppard D, Broad G, Livermore L (2014) Checklist of British and Irish Hymenoptera - Sawflies, ‘Symphyta’. Biodiversity Data Journal 2: e1168.

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

4. 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.

5. 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