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DIPTERA REPORT 2018 PETER VINCENT The hot dry summer has done no favours for our flies and in my experience 2018 has been in general a poor one for insects. Our fly fauna suffers badly in major drought years; as when plants come under drought stress they produce less nectar for adult flies to feed upon and phytophagous species do not thrive when host plants wither and die. The many flies whose larvae require wet substrates struggle to complete their life cycle as wetland habitats dry out. As always there are winners and losers, some species have done well and appeared in reasonable numbers, but these are fewer than they should be. Although, not considered a positive thing in some peoples opinion, the house flies, Musca domestica Linnaeus, 1758 and M. autumnalis De Geer, 1776 seem to be in greater abundance this year. But some sage words on the state of British diptera, and perhaps by association the whole natural environment, at the current time was given by the prominent ecologist and dipterist Alan Stubbs commenting in British Wildlife magazine (Stubbs, 2018) ‘It is not all doom and gloom but the widespread feeling is that things are not what they used to be, even in good habitat’. Nevertheless, this year I am pleased to have received an increased number of queries and records from a larger number of Suffolk naturalists. Although physical voucher specimens are the gold standard in diptera identification, with modern digital cameras and technology it has never been easier to photograph living flies and I am pleased to accept records from photographs if they can be identified with certainty. Unfortunately many flies cannot be identified from images unless the critical features can be seen. David Fairhurst and Jamie Smith both sent me photographs of the spectacular Conopid Conops vesicularis Linnaeus, 1761 from Snape and Leiston respectively (Plate 5). This is the largest British Conops (body length 12-14mm) with a brown and yellow hornet-like appearance. It is a scarce species in Suffolk, although perhaps it will become more frequent as one of its host species the Hornet Vespa crabro Linnaeus, 1758 is becoming more frequent. Another, good Suffolk record was of the horsefly Atylotus latistriatus (Braeur, 1880) from Butley by Gary Lowe. All Atylotus species are restricted to narrow habitat types; A. latistriatus is a specialist saltmarsh species, recorded only in Suffolk from the Stour and Alde estuaries. In addition, I received specimens of the Drosophalid Cacoxenus indagator, from David Basham, that he had collected from the nest cells of the bee Osmia bicornis (Linnaeus, 1758) taken from his ‘bee hotel’. This fly is known to be a well known cleptoparasite of O. bicornis, but this is the first record from Suffolk, with apparently few records nationally. Another case of hymenopterists’ helping dipterists is Hawk Honey’s record of the Conopid Thecophora atra (Fabricius, 1775). Although, quite a common species, especially in the South of England, there are few records of T. atra from Suffolk. As I tend to collect material in the field during spring, summer and autumn and then spend time during the winter with my microscope identifying the flies I have collected, most of the records of flies I mention further into this report relate to 2017. Of most significance during this period was the discovery of Muscina pascuorum
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(Meigen, 1926) on the grazing marshes at Sizewell Belts Suffolk Wildlife Trust reserve on the 12 August 2017. This was only the second British record of this muscid, the first being found during a pitfall-trapping survey at RSPB Minsmere in 2005 undertaken by M.G. Telfer and identified by P. Skidmore (Skidmore & Pont, 2008). M. pascuorum is considered to be the rarest of the European Muscina; it is present in most of Western Europe from southern France to southern Sweden and Finland. It seems probable that as Muscina species are powerful fliers that these individuals were casual migrants from the near-continent; east Suffolk being well positioned to receive such migrants, although, a small resident population could possibly be established on the coastal marshes of Suffolk. Another noteworthy record was of the tiger cranefly Nephrotoma quadristriata (Schummel, 1833) from Kessingland Beach in August 2017. In Britain this fly is considered to be a rare (RDB2) specialist of sand dunes and found almost exclusively on the West coast of England and Wales. This Kessingland record appears to be not only to be the first record from Suffolk, but also from East Anglia and the whole East coast of England. It was collected from the vegetation around the edge of an extensive damp area in the dunes (slacks), habitat typical for this species in Britain. In addition to species mentioned above, some interesting and uncommon Suffolk species I have recorded include, the Calliphorids, Pollenia griseotomentosa (Jacentkovský, 1944 and P. labial Robineau-Desvoidy, 1863, the Canacid Xanthocanace ranula (Loew, 1874), the Chloropids, Melanum laterale (Haliday, 1833), Meromyza femorata Macquart, 1835, Tricimba cincta (Meigen, 1830) and Elachiptera tuberculifera (Corti, 1909), the Diastatid Diastata fuscula (Fallén, 1823), the Dolichopids, Dolichopus excisus Loew, 1859, D. signatus Meigen, 1824, Syntormon aulicum (Meigen, 1824), Teuchophorus calcaratus (Macquart, 1827) and T. nigricosta (von Roser, 1840), the Empid Dolichocephala guttata (Haliday, 1833), the Ephydrid Discomyza incurva (Fallén, 1823), the Fannid Fannia genualis (Stein, 1895), the Heleomyzid Suillia laevifrons (Loew, 1862), the Keroplatids, Macrocera centralis Meigen, 1818 and M. stigmoides Edwards, 1925, the Limonid Trimicra pilipes (Fabricius, 1787), the Micropezid Neria ephippium (Fabricius, 1794), the Milichid Madiza glabra Fallén, 1820, the Muscid Phaonia fallen Michelsen, 1977, the Scathophagid Ceratinostoma ostiorum (Haliday in Curtis, 1832), the Sciarid Sciara humeralis Zetterstedt, 1851, the Sciomyzids, Ditaeniella grisescens (Meigen, 1830) and Limnia paludicola Elberg, 1965, the Sepsid Sepsis thoracica (Robineau-Desvoidy, 1830), the Syrphid Volucella inflata (Fabricius, 1794), and the Tachinid Subclytia rotundiventris (Fallén, 1820). References Skidmore, P. & Pont, A. C. (2008). Muscina pascuorum (Meigen, 1926)) (Diptera, Muscidae) in Britain. Dipterists Digest (second series) 15: 20-22. Stubbs. A. (2018). Flies. British Wildlife 29: 447-449.
Peter Vincent Pennyfields, Rectory Road, Middleton, Suffolk IP17 3NW
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Jamie Smith
SUFFOLK DIPTERA CHECKLIST
Plate 5: A spectacular Conopid Conops vesicularis L. Leiston, 14 May 2018 (p. 47).
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