Taxonomy

Platycheirus podagratus

Distribution

Species Biology

Preferred environment

Wetland/open ground; acid fen, margins of oligotrophic lakes, rivers and brooks in unimproved grassland, taiga and moor; unimproved montane and alpine grassland. The few Irish records of this syrphid are from humid, unimproved grassland in the west. Two of them are from traditional hay meadows, which have now disappeared. The others are from grassland strips along streams/small rivers, within blanket bog. P. podagratus is particularly a species of small sedge beds in upland marshes, for instance along the shores of montane and subalpine lakes. Loss of unimproved hay meadows and overgrazing of its other habitats in Ireland by sheep, particularly severe during the last part of the 20th century, could easily have led to virtual eradication of this species.

Adult habitat & habits

Flies low among ground vegetation of Briza, Carex, Juncus etc., usually close to water; as easily detected by use of a sweep net as by direct observation.

Flight period

End May/mid July and on to mid August at higher altitudes. Larva: not described, but illustrated in colour by Rotheray (1994).

Flowers visited

Cyperaceae.

Irish reference specimens

In the collections of NMI

Determination

Speight and Goeldlin (1990), Haarto and Kerppola (2007a), Bartsch et al (2009a). The adult insect is illustrated in colour by Stubbs and Falk (1983), Torp (1994) and Bartsch et al (2009a).

Distribution

World distribution(GBIF)

From the Faroes (Jensen, 2001) and Fennoscandia south to the Pyrenees; from Ireland eastwards through northern Europe and mountainous parts of central Europe into Russia and on to SE Siberia; in N America from Alberta and Ontario. Further north in Europe P. podagratus is frequent (to as far north as northern Norway). It is also frequent in the Alps and has a wide range beyond Europe, through Asiatic parts of the Palaearctic and in N America. It is, however, absent from the Atlantic zone of Europe further south than Denmark, except for in Britain and Ireland.

Irish distribution

Recorded as occurring in Ireland in Coe (1953), but at that time this insect was confused with other European Platycheirus species. The presence of this species in Ireland was confirmed by Speight and Goeldlin (1990). P. podagratus appears to have been largely confined to the northwest of the island. There are very few records of the species from Ireland during the last 50 years and it would validly be classed as endangered here. It is a candidate for inclusion on any listing of insects requiring protection throughout the island. 

Temporal change

Records submitted to Data Centre in 2021

The following map is interactive. If you would prefer to view it full screen then click here.

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.

Images