Taxonomy
Criorhina floccosa
Distribution
Species Biology
Preferred environment
Deciduous forest; humid Fagus and Quercus forest with over-mature and senescent trees, up to the upper altitudinal limit of Fagus. The only indigenous Irish trees with which C. floccosa is known to be associated are oak and elm, but on the continent it occurs also with beech and Irish records would suggest that beech is as important as oak in maintaining this insect here - it is doubtful that elm plays a significant role, especially following the recent devastation of Ulmus species in Ireland by disease. C. floccosa has also been reared in Ireland from a tunk cavity in sycamore, and it is likely that this tree, too, plays a significant role in the survival of C. floccosa in Ireland. Unlike C. berberina, C. floccosa does not occur in conifer forest and is not known to have any association with any coniferous tree species.
Flight period
Beginning April/beginning July, with records beyond mid June mostly from higher altitudes. Larva: described and figured by Rotheray (1991) and figured in colour by Rotheray (1994), from larvae collected from a rot-hole in the trunk of Ulmus and wet, decaying roots of Fagus stumps; has also been found within the mass of wet tree humus and wood fragments filling a large, winter-flooded rot-hole, within the trunk of a large, live Acer pseudoplatanus, at 1.5m from the ground.
Flowers visited
Umbellifers; Cornus sanguinea, Crataegus, Photinia, Prunus spinosa, Ribes alpina, Rubus idaeus, Sorbus aucuparia, S. aria.
Irish reference specimens
In the collections of NMI and UM
Determination
van der Goot (1981). See Key provided in StN Keys volume. The adult insect is illustrated in colour by Bartsch et al (2009b), Stubbs and Falk (1983) and Torp (1994).
Distribution
World distribution(GBIF)
Southern Sweden and Denmark south to the Pyrenees; from Ireland eastwards through central Europe (plus northern Italy and the former Yugoslavia) into European parts of Russia as far as the Caucasus. C. floccosa occurs widely in western and central Europe, but is regarded as threatened in the Atlantic seaboard countries except for France. It is also regarded as threatened in Germany and Switzerland. C. floccosa is endemic to Europe.
Irish distribution
Recorded as occurring in Ireland in Coe (1953). Within Ireland, records of C. floccosa are few but widely scattered, from one end of the island to the other, making this syrphid relictually distributed here. Most recent records are from protected sites and the species cannot be regarded as much threatened, though it perhaps should be categorised as vulnerable.
Temporal change
Records submitted to Data Centre in 2024
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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.