Taxonomy

Eristalis intricarius

Distribution

Species Biology

Preferred environment

Wetland; raised bog/fen/fen carr/poorly-drained deciduous forest and humid, seasonally-flooded grassland. This Eristalis species is particularly frequent in Ireland. It is among the earliest syrphids to appear in the spring and has a succession of generations through into the autumn. Humid grassland that is even slightly flooded for part of the year and is used for grazing of cows seems especially suited to the needs of E. intricarius, and under those conditions its larvae may develop in water-logged cow-dung. But this species demonstrates no general dependency on cow dung, being generally absent from the standard farmland landscape of green fields plus hedges, and occurring in many locations from which livestock are absent. However, it can occur in Ireland in association with (and has been bred from) constructed wetlands, introduced to farmland for treatment of livestock waste. In more natural conditions, it occurs abundantly in fen and can be found also at the lagg edge of cut-over valley bog, where pools influenced by ground water are present.

Adult habitat & habits

In early Spring usually in the vicinity of scrub, carr or tall reeds, providing shelter; males hover along paths in carr and woodland at up to 5m; later in the year present in a wide range of wetland types, including boggy pasture; adults visit flowers of both low-growing plants and trees.

Flight period

Mid April/end August. Larva: described and figured by Hartley (1961), occurs in semi-liquid mud and fen peat beside water, in field drains, slurry and cow dung on water-logged ground.

Flowers visited

White umbellifers; yellow composites; Ranunculaceae; Armeria maritima, Cakile, Calluna vulgaris, Cirsium, Crataegus, Filipendula, Jasione, Ligustrum, Lythrum, Mentha, Polygonum cuspidatum, Prunus spinosa, Pyrus communis, Rhododendron, Rubus,Salix, Succisa.

Irish reference specimens

In the collections of NMI and UM

Determination

See Key provided in StN Keys volume and Hippa et al (2001), who figure the male terminalia. Male terminalia are figured by Kanervo (1938). The adult is illustrated in colour by Bartsch et al (2009b), Kormann (1988), Stubbs and Falk (1983), Torp (1984, 1994) and van der Goot (1986).

Distribution

World distribution(GBIF)

Iceland, Fennoscandia and the Faroes (Jensen, 2001) south to central Spain, but increasingly confined to mountainous regions towards the southern limit of its range and absent from much of southern Europe; from Ireland eastwards through much of northern and central Europe (though very localised in the Alps) into Russia as far as eastern Siberia. 

Irish distribution

Recorded as occurring in Ireland in Coe (1953). Although widely distributed and frequent in Ireland and in other parts of Europe's Atlantic seaboard countries northwards from northern France (inclusive), E. intricaria becomes progressively localised as one travels further south or into central Europe. It is, however, frequent in northern Europe, where its range extends eastwards into Asiatic parts of Siberia.

Temporal change

Records submitted to Data Centre in 2019

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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