Forest/open ground; along brooks in open conifer forest (humid Pinus, Abies, Picea) and Betula woodland. P. nielseni is essentially an upland and western species in Ireland, found where Betula/Salix scrub is present in oligotrophic Molinia grassland/moorland or partially-reclaimed blanket bog, especially along streams. It is not, however, a wetland insect per se. It is entirely absent from the farmed landscape of green fields and hedges, from suburban situations and from coastal habitats. It may be regarded as an anthropophobic species, able to use man-modified habitats to only a marginal extent, unless it is recognised that where it occurs today it is occupying largely secondary habitats engendered by long-term (i.e. hundreds of years) grazing activity, in what was probably Pinus/Betula forest previously. Realistically, P. nielseni is a species of boreal mixed forests and humid, montane conifer forests, which has survived in Ireland in an extensively deforested landscape. Today's conifer plantations do not seem to provide an alternative habitat for P. nielseni, except during the establishment phase, or where a plantation includes a significant proportion of open area, allowing invasion by Betula and Salix.
Adult habitat & habits
Clearings and tracksides, usually along brooks; beside scrub-fringed streams in montane/alpine pasture up to 2,000m (Alps); males hover at 1 - 2m in clearings etc, within one small area often occurring together in large numbers (S Ball, pers.comm.).
June/September. Larva: undescribed
Aegopodium, Anthriscus, Barbarea vulgaris, Caltha palustris, Cirsium arvense, Geranium sylviaticum, Geum rivale, Ranunculus, Senecio.
Irish reference specimens
In the collections of NMI and UM
Haarto and Kerppola (2007a), Bartsch et al (2009a). Differences between the legs of male P. nielseni and male P. peltatus may be seen from comparison of the figures in Vockeroth (1990) and Speight and Vockeroth (1988). Van Steenis and Goeldlin (1998) provide a key separating the female from females of other European peltatus group species. But care has to be exercised in employing the feature relating to relative widths of the terminal tergites used in the last couplet of their key, since the condition described for P. peltatus (Mg.) may also occur in P. nielseni. The adult male is shown in colour by Bartsch et al (2009a).
Fennoscandia south to northern France (Vosges); from Ireland eastwards through northern and central Europe (including northern Italy), where it is frequent in the central Alps, into European parts of Russia; Siberia; scattered records from N America from Alaska through much of Canada and south through the Rocky mountains to Colorado. It is primarily a northern European insect, which extends southwards through mountainous country as far as the Alps, where it is frequent in the Abies/Picea zone. It is a Holarctic syrphid, though little seems to be known of its occurrence in Asiatic parts of the Palaearctic.
Added to the Irish list by Vockeroth (1990). Most Irish P. nielseni records are from the west of the island, and the species appears to be absent from lowland areas further east. This species cannot be classed as threatened here, but neither is it frequent.
Records submitted to Data Centre in 2023
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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.