Xiphydria prolongata - Willow Swordtail

The Willow Swordtail is one of three species in the genus in Britain apparently more widespread in the south-east but recorded north to Northumberland and west into Wales (Musgrove, 2022). Xiphydria prolongata is the only one of the three species to have a red girdle on the abdomen covering at least tergite four. The abdomen also has lateral white spots.

Larvae bore into the green-barked wood of willow trees and can become a serious pest in the production of cricket bat willows causing reduced vigour, die-back and damaging heartwood. Females inject their eggs below the bark where the bark is fissured and 2 to 3 mm thick. Infection rates can be high with over a hundred adults emerging from a single trunk. Around 75% of emerging adults are male. Males tap the timber with the tip of their abdomen creating a noise that can be audible from several metres away. Males emerge in May and June with females emerging a few weeks later peaking in July.

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Size: 6 - 18mm

GB IUCN Status: Least Concern
GB Rarity Status: None

Distribution: England, Wales

Flight period: June to August

Plant associations: Salix spp. (Willows), Populus spp. (Poplars), and Ulmus spp. (Elms).


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

Burtt Davy, J., Day, W.R., Chrystal, R.N., Bryce, J. 1958. 2nd Edition. Cultivation of the cricket bat willow. Bulletin No. 17. Forestry Commission, London.

Chrystal, R.N., Skinner, E.R. 1932 Studies in the Biology of the Woodwasp Xiphydria prolongata Geoffr, (dromedarius F.) and its parasite Thalessa curvipes Grav., The Scottish Forestry Journal Vol. 46, 1. Douglas and Foulis, Edinburgh.

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

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 Natural England, unpublished

Shaw, M. R. & Liston, A. D. 1985: Xiphydria longicollis (Geoffroy) (Hymenoptera: Xiphydriidae) new to Britain. - Entomologist's Gazette, Faringdon 36: 233-235

Westwood, J. O. 1845: Memoirs on various Species of Hymenopterous Insects. - (The) Transactions of the Entomological Society of London, London Vol. 4(2): 123-141