Xeris spectrum (Linnaeus, 1758)

Xeris spectrum

The presence of this species in Britain is unclear. On examination by Goulet et al, all specimens of British material in the British Museum of Natural History were determined to actually be Xeris pallicoxae. There may be Xeris spectrum specimens in private collections and municipal collections. Further investigation is required in this regard.

In pallicoxae the yellowish-white band on the pronotal shoulders is largely smooth between raised peaks, whereas in spectrum the bands are heavily ridged. In lateral view the pronotum of pallicoxae has only sparse pits, whilst spectrum has numerous coarse pits over at least one third of the area such that the margins form raised reticulation. The female has black coxae on at least on their outer face (reddish-brown in pallicoxae).

The male has a large yellowish-white spot, quite sharply outlined, extending beyond the genal carina onto the occiput (comma shaped). There is a wide reddish-brown band on the basal hind tarsal segment and the third to fifth tarsal segments are similarly reddish-brown.

Larvae feed in the timber of coniferous trees and take 2 or 3 years to emerge.

Jump to other Urocerus species

Size: 15 - 30mm (excl. ovipositor)

Status: Rarely encountered

Distribution: England, Wales, Ireland

Flight period: June to October

Plant associations: Pinaceae (coniferous trees)

References:

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

Goulet, H., Boudreault, C. and Schiff, N.M., 2015. Revision of the world species of Xeris Costa (Hymenoptera: Siricidae). Canadian Journal of Arthropod Identification, 28.

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