Taxonomy

Cheilosia fraterna

Distribution

Species Biology

Preferred environment

Deciduous forest/freshwater; along streams and rivers with marginal tall herb communities, in open forest (acidiphilous Quercus, humid Fagus). C. fraterna is characteristically encountered alongside rivers and streams, in unimproved grassland or open areas in deciduous forest. It has been reared in Scotland from Cirsium palustre, a host plant widely distributed and common in Ireland and the adult feeds from flowers equally generally available. Indeed, there seems no obvious ecological explanation for the apparent absence of C. fraterna from Ireland. That, together with the few existing doubtful Irish records, makes the situation of this species something of a mystery in Ireland. If it were present, the expectation would be for records to be reasonably frequent and widely scattered through the island. Its wide distribution in continental Europe, together with the fact that it is known from the Scottish Highlands to the south coast of England in Great Britain, demonstrate that this hoverfly has a wide ecological tolerance. It is not a species known to migrate, but the narrow strait of sea water between Scotland and Northern Ireland, in particular, should not represent an insuperable obstacle to colonisation of Ireland by this fly.

Adult habitat & habits

Clearings and tracksides, usually along streams or rivers.

Flight period

April/June and at higher altitudes July to August/September. Larva: described and figured by Rotheray (1988a); mines stems and basal rosettes of Cirsium palustre; other species of Carduus and Cirsium are also cited as larval foodplants by Reemer et al (2009).. This species overwinters as a puparium.

Flowers visited

Caltha, Ranunculus, Stellaria,Taraxacum.

Irish reference specimens

None known

Determination

van der Goot (1981). The adult insect is illustrated in Bartsch et al (2009b), Stubbs and Falk (1983) and Torp (1994). This species is very similar to C. bracusi Vujic & Claussen. Distinctions between these two species are given by Vujic and Claussen (1994b). The surstyli of the male terminalia are figured by Stubbs and Falk (2002).

Distribution

World distribution(GBIF)

Fenno-Scandia south to the Pyrenees, montane in southern parts of its range; Britain eastwards through central Europe into European parts of Russia and on into much of Siberia. Added to the Irish list by Speight et al (1975). 

Irish distribution

The single specimen mentioned in Speight et al (1975) cannot be re-located and the Irish specimen subsequently recorded in Nash and Speight (1976) has proved to be misidentified. There have been no further records of C. fraterna from Ireland. The status of C. fraterna as an Irish insect must be regarded as doubtful and requiring confirmation. Until and unless the presence of this species in Ireland can be verified there is no adequate basis for including it on the Irish list.

Temporal change

Records submitted to Data Centre in 2021

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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.

Images