Taxonomy
Brachypalpoides lentus
Distribution
Species Biology
Preferred environment
Forest with overmature trees; especially Fagus, Picea and Quercus and including evergreen oak forest. In Ireland, this insect is primarily associated with mature/overmature oak (Quercus) woodland, but will utilise old beech (Fagus) when this is available and has been reared in Ireland from wet, fungus-riddled wood at the trunk-base of an old, living beech. The scarcity of oak woodland in Ireland today makes mature/ overmature beech a significant contributer to the survival of B.lentus. Oak is absent from some Irish localities from which B.lentus has been recorded, but there is no indication that ash (Fraxinus) or birch (Betula) provide alternative larval habitat - sycamore (Acer pseudoplatanus) or wych elm (Ulmus glabra) may be involved. Although in continental Europe this species occurs in mature/overmature Abies/Picea forest it has not been found in British or Irish conifer plantations. This is presumably due to a lack of appropriate larval habitat, occasioned by plantation management practices employed and the lack of sufficiently mature trees. B. lentus has to be regarded as an anthropophobic insect in Ireland. It does not occur in the standard farmland landscape of green fields and hedges any more than in conifer plantations. Neither is it to be found in suburban gardens.
Adult habitat & habits
Running on foliage of bushes, Rubus fruticosus etc. at the edge of forest clearings; also on the ground near fallen and felled trees.
Flight period
April/June plus July at higher altitudes. Larva: undescribed, but the species has been bred from damp, fungus-riddled rotten wood within the trunk base of an old, living Fagus and is included in the keys provided by Rotheray (1994), where it is distinguished from larvae of related genera and its fore body is figured. B. lenta larvae have also been found beneath the bark of Picea, by Kassebeer (1993).
Flowers visited
Umbellifers; Crataegus, Galium, Rubus idaeus, Sorbus aucuparia
Irish reference specimens
In the collections of NMI and UM
Determination
Speight (1999b). The male terminalia are figured in Hippa (1978). The adult insect is illustrated in colour in Bartsch et al (2009b), Colyer and Hammond (1951), Stubbs and Falk (1983), Torp (1984, 1994), van der Goot (1986) and Kormann (1988). B. lentus is superficially very similar in appearance to Chalcosyrphus piger (Fab): see Key provided in StN Keys volume.
Distribution
World distribution(GBIF)
Scandinavia to the Pyrenees and central Spain; Ireland through central Europe into European parts of Russia; southern Europe eastwards to the former Yugoslavia and Greece and on into Asia Minor. B. lentus is widely distributed and not infrequent in Europe in general, except in the north. Its range extends beyond Europe, into Asia Minor.
Irish distribution
Reported from Ireland in Coe (1953). B. lentus is an infrequent species in Ireland, though there are scattered records from most parts of the island. Its larval microhabitat requirement for overmature, living trees ensures that it is very unlikely to become more frequent here in either short or medium term.
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.