Taxonomy
Chrysotoxum arcuatum
Distribution
Species Biology
Identification
Recorded in Ireland under the name C. arcuatum. It is correctly referred to as C. fasciatum
Preferred environment
Wetland/forest, fen carr, edges of raised bogs; along stream edges and in poorlydrained clearings in humid/wet forest (both conifer and deciduous) and conifer plantations; also in the subalpine zone, in unimproved grassland and heath. In Ireland this syrphid occurs in clearings and along tracksides in deciduous woodland and conifer plantations, and is as frequently encountered along streams in moorland, or along margins of bog and fen. However, it is mostly found at rather lower altitudes, up to 800 ft., although in the Alps it occurs up to the levels of subalpine grassland. Essentially, C. fasciatum is here a species of unmanaged margins of waterways and wetlands. It does not normally occur here in association with karst limestone areas. Its sparse occurrence in conifer plantations in Ireland is in contrast to its frequency in humid conifer forests in continental Europe, and is presumably dictated by management and husbandry conditions current in Irish commercial forestry, which result in considerable disturbance of soil surface layers, shaded stream margins, comprehensive land-surface drainage and a general lack of ground vegetation. This species does not persist in the standard Irish farmland landscape of green fields and hedges. Neither does it occur in gardens or parks. It has thus to be regarded as primarily an anthropophobic syrphid in Ireland.
Adult habitat & habits
Woodland clearings and tracksides, in the vicinity of water or poorly-drained ground; also at the edge of bog and acid fen where Betula/Salix scrub has developed; flies low among ground vegetation and in a manner resembling the flight of the Vespula species it mimics, but its flight is soundless.
Flight period
May/September, with peaks in June and August and occasional specimens on undescribed.
Flowers visited
Yellow composites; white umbellifers; Calluna, Frangula alnus, Hypochoeris, Leontodon, Leucojum aestivum, Ligustrum,Luzula sylvatica, Potentilla erecta, Ranunculus, Rubus fruticosus, R. idaeus, Salix repens, Sorbus aucuparia.
Irish reference specimens
In the collections of NMI and UM.
Determination
van der Goot (1981). The adult insect has been figured in colour by Kormann (1988), Stubbs and Falk (1983), Torp (1984, 1994) and van der Goot (1986). Ill-conceived application of the International Code of Zoological Nomenclature suggests use of the name arcuatum for this species, for the last 20 years used over most of Europe for another Chrysotoxum species. The name "arcuatum L." has in this way become meaningless, in that the biological species to which it has been applied in the literature (and the literature defines the biological species in human terms) is too often uncertain and open to misinterpretation. The name "arcuatum L" is thus no longer used in this database.
Distribution
World distribution(GBIF)
Fennoscandia south to the Pyrenees and northern Spain; from Ireland eastwards through northern and mountainous parts of central and southern Europe (northern Italy, the former Yugoslavia, Bulgaria) into European parts of Russia; through Siberia from the Urals to Kamchatka; Japan.
Irish distribution
Recorded in Ireland in Coe (1953), under the name C. arcuatum. C. fasciatum is not uncommon in Ireland and is recorded from most parts of the island, becoming noticeably more frequent in its northern half. This would be in keeping with its European distribution - further south than the Ardennes, this insect is almost confined to mountainous country. But it has an extensive range outside Europe, in Asia, reaching the Pacific and Japan.
Temporal change
Records submitted to Data Centre in 2024
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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.