Taxonomy
Xylota jakutorum
Distribution
Species Biology
Preferred environment
Conifer forest, with mature and overmature trees; partially anthropophilic, extending its range into commercial conifer plantations in parts of Europe previously covered in deciduous woodland; found with Abies, Picea and Pinus. In south-east Europe, apparently also in montane deciduous forest (A.Vujic, pers.comm.). X. jakutorum is characteristically an insect of mature/overmature coniferous forests, occurring with spruce, fir and pine. In Ireland this species is associated with mature conifer plantations, the larvae presumably occurring in the cut stumps of felled trees. Irish distribution data for the fly reflect neither the distribution nor frequency of Irish conifer plantations, however. In part this may be due to the frequent practice of treating spruce stumps with urea, to reduce the numbers of the weevil Hylobius abietis, rendering the stumps as unusable by X. jakutorum as by other saproxylics. Even so, some stumps will almost inevitably escape treatment. The present distribution of X. jakutorum may well also reflect the history of spruce plantations in Ireland, in that most were planted within the last 50 years and are only now reaching maturity and being felled for the first time - until very recently larval microhabitat suitable for X. jakutorum (i.e. spruce stumps) would have been very much scarcer in conifer plantations than it is today. The great frequency of X. jakutorum encountered by Tom Gitings (pers.comm.), in mature spruce plantations during survey work 2001-5 suggests that rapid expansion of Irish X. jakutorum populations may now be underway. There are reports of X. jakutorum occurring in association with deciduous forest in some parts of Europe, and in Donegal (Glenveagh National Park) this syrphid is frequent in oak woodland distant from conifer plantations (though conifer plantations do remain within the park). Whether this species is able to develop in rotting oak wood is unknown, and certainly, over most of its known range it shows no association with Quercus species. In Scotland this insect is associated with humid Pinus sylvestris forest. Whether X. jakutorum represents some element of the otherwise extinct Irish P. sylvestris fauna that has somehow managed to survive until the advent of commercial forestry in Ireland is doubtful. This possibility was examined by Speight (1985b). Today it seems dependent upon conifer plantations for its survival here.
Adult habitat & habits
Running on the foliage of bushes and shrubs at tracksides and edges of clearings etc.; frequently in the sun on fallen or felled timber and tree stumps or on the ground in the vicinity of old trees.
Flight period
May/August, with peak in June/July and occasional specimens into September. Larva: Rotheray (1994) established that the larva of this species (under the name X. coeruleiventris) occurs in sap runs on Abies, caused by the weevil Hylobius abietus. The larva is described and figured (as the larva of X. caeruleiventris) by Rotheray and Stuke (1998), from larvae collected from sap-filled borings of Hylobius beneath the bark of Pinus sylvestris stumps.
Flowers visited
Umbellifers; Potentilla erecta, Ranunculus, Rosa rugosa, Rubus idaeus, Sorbus aucuparia.
Irish reference specimens
In the collections of NMI and UM.
Determination
See key provided in the StN Keys volume; Bartsch et al (2009b). Bartsch et al (2002) figure the male terminalia of X. jakutorum and the closely similar X. caeruleiventris. X. jakutorum appears in most recent European literature, including the keys of Speight (1999b), Verlinden (1991) and Bradescu (1991), under the name X. coeruleiventris, a mis-spelling of the name caeruleiventris. X. jakutorum was confused with X. caeruleiventris in European literature for many years. In the female, the presence or absence of pale markings on the abdominal tergites is unreliable (Bartsch et al, 2002) as a basis for separating X. caeruleiventris and X. jakutorum, since pale abdominal markings may be entirely absent in females of both species (it is suspected they are always absent in X. caeruleiventris females). Bartsch et al (2002) figure the male terminalia of both species - these figures show how closely similar they are. The adult of X. jakutorum (as X. coeruleiventris) is illustrated in colour by Bartsch et al (2009b), Kormann (1988), Stubbs and Falk (1983) and Torp (1994).
Distribution
World distribution(GBIF)
From Fennoscandia south to the Pyrenees; Italy; from Ireland eastwards through central Europe to European parts of Russia and on into Asia through much of Siberia. This species is frequent from central Scandinavia southwards to central Europe, but is largely confined to mountain ranges further south. It ranges beyond Europe into Asiatic parts of the Palaearctic.
Irish distribution
Added to the Irish list by Speight (1976a) under the name coeruleiventris Zetterstedt. Additional Irish records are published by Nash and Speight (1976). Existing Irish records are widely scattered, but predominantly in the western half of the island. The species is arguably undergoing a rapid expansion in Ireland at present and there is no basis for regarding it as threatened here.
Temporal change
Records submitted to Data Centre in 2025
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References
Publications
Speight, M. C. D. (2008) Database of Irish Syrphidae
(Diptera). Irish Wildlife Manuals, No. 36. National Parks and Wildlife Service.
Department of Environment, Heritage and Local Government, Dublin, Ireland.
Speight, M.C.D. (2014) Species accounts of European
Syrphidae (Diptera), 2014. Syrph the Net, the database of European Syrphidae,
vol. 78, 321 pp., Syrph the Net publications, Dublin.