Taxonomy
Platycheirus granditarsus
Distribution
Species Biology
Preferred environment
Open ground/wetland; humid, unimproved grassland subject to flooding or not, including oligotrophic Molinia grassland, marsh, fen, edges of raised bogs.This syrphid is characteristic of humid grassland subject to periodic flooding. Until recently, this secondary habitat has provided it with an extensive range within Ireland, away from its more natural wetland sites, in fen and marsh. However, general land-surface drainage has been carried out on a considerable scale during the last half of the 20th century and today P. granditarsa cannot today be regarded as an insect typical of the Irish farmland landscape. It does not normally occur in either croplands or the productive area of intensive grasslands, but in Ireland has been bred from setaside strips and from the taller vegetation patches that surround cow dung in humid grassland. In wetlands, it occurs primarily in fen and around the margin of raised bogs. It can also occur along the margin of running or standing water bodies, in association with stands of tall herb vegetation. Where patches of humid, seasonally-flooded grassland persist it may be found in various situations, such as within conifer plantation.
Adult habitat & habits
Flies among tall (1m or more) ground vegetation; settles on stems of Juncus, Phragmites etc.; males hover at up to 2m in more open spots within humid grassland etc.
Flight period
End of May/September and occasional specimens in October. Larva: undescribed, but this species has been collected in numbers from emergence traps installed over the taller patches of grass that develop around cow pats, in a cattle-grazed, humid grassland and from emergence traps installed over setaside vegetation. Barkemeyer's (1994) reference to occurrence of larvae of this species in cereal crops seems to be in error, since the source he quotes (Chambers et al, 1986) makes no mention whatever of Platycheirus granditarsus.
Flowers visited
White umbellifers; Alisma plantago-aquatica, Bidens cernua, Leontodon, Lycopus europaeus, Polygonum cuspidatum, Ranunculus, Senecio jacobaea.
Irish reference specimens
In the collections of NMI and UM
Determination
van der Goot (1981). Until recently, this species has been consigned to the genus Pyrophaena, which Vockeroth (1990) argues should be included in Platycheirus. The adult insect is illustrated in colour by Colyer and Hammond (1951), Stubbs and Falk (1983), Torp (1984, 1994) and van der Goot (1986).
Distribution
World distribution(GBIF)
From Iceland and Fennoscandia south to northern France and the Alps; from Ireland eastwards through northern and central (very localised in the Alps) Europe into European parts of Russia; across Siberia to the Pacific coast (Kuril Isles); in N America from Alaska to Quebec and south to Colorado. Beyond Europe, P. granditarsus ranges through Asiatic parts of the Palaearctic to the Pacific and is very widely distributed in the Nearctic.
Irish distribution
Recorded as occurring in Ireland in Coe (1953). Until recently, P. granditarsus has been an extremely frequent and widely-distributed species in Ireland, in marked contrast to its situation in continental Europe, where it is very localised, especially away from the Atlantic seaboard. Although remaining widely distributed in Ireland, it is now much more confined to the wetter, unused patches surviving within the farmland infrastructure, and to the margins of drainage ditches etc.
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.