|
| Insects of Britain and Ireland: the genera of Syrphidae (hoverflies) |
Adult flies. The flies somewhat resembling a potter bee (or Eucera), or megachilid bee-like (cf. Osmia spp.); black or shiny-metallic, sometimes brassy; small to medium sized; 10–13 mm long. Wings 9.75–15 mm long.
The head wider than the thorax. The face with a central knob to without a central knob (with a slight knob). The eyes depicted as hairy. Antennae relatively long, porrect; with their bases approximated (on a tubercle); black. The antennal bristle apical; simple.
The humeri hairy, and readily visible behind the head. The thorax shaggy with soft hair; plain; without longitudinal stripes (bronze). The scutellum flat, with a well defined edge; aeneous, or black. Wings plain. Wing veins R2+3 and R4+5 not forming a closed cell. The anterior cross vein R-M in cell R5 crossing it before the middle of the adjoining discal cell. Vein R4+5 without a conspicuous curve projecting into the cell R5; without a backwardly projecting, incomplete transverse veinlet. The lower outer marginal vein markedly diverging from the posterior wing margin. The upper and lower outer marginal cross veins strongly stepped. The upper outer marginal cross-vein conspicuously bent near the base the base; not re-entrant. The alula distinct.
The abdomen markedly wider than the thorax; broadly oval, or obovate. The male abdomen with 4 visible segments. The abdomen conspicuously furry; somewhat contrastingly patterned to not contrastingly patterned. The patterning attributable to the furry hair coat. The spiracles of the third abdominal segment borne at or near the anterior corner of each side.
Larvae and pupae. The larvae briefly tapering posteriorly; tailed. The anal segment tapered gradually to the spiracular process (the extended segment bearing a pair of fleshy projections). The larvae scarcely flattened (the prolegs of abdominal segments 1–6 partially fused into a single oval structure); blackish, plain; with hooks on the thorax (two groups of 3–4, just behind and lateral to the anterior spiracles); mouth without triangular sclerites; anal segments with lappets (but the first two pairs on the anal segment reduced). The larvae saprophagous; in rot-holes and in rotten wood (recorded from Larix, Pinus and Fagus).
Classification. Subfamily Milesiinae; tribe Callicerini.
British representation. 3 species in Britain.
Illustrations. • C. aurata: Verrall. • 15 genera (from Walker). 1, Ceriana conopsoides (adventive?), head in side view and extremity of wing. 2, Callicera aurata, with detail of antenna. 3, Microdon mutabilis, antenna and wing. 4, Eumerus strigatus, head in side view and wing. 5, Eristalis tenax: male head from above (5a), female head from the side (5b), and wing of female (5c). 6, Helophilus pendulus: head of male from above (6a) and from the side (6b), and extremity of wing (6c). 7, Merodon clavipes (extinct in Britain): head in side view, and hind leg of male. 8, Tropidia scita, male: head and extremity of wing. 9, Syritta pipiens, male, with head in side view (9a). 10, Xylota sylvarum, male: head (10a), antenna (10b), and base of hind leg showing coxa with a small spine (10d). 11, "Milesia speciosa" (Caliprobola speciosa?): head in side view (11a), wing extremity (11b), and base of hind leg (11c). 12, Criorhina berberina, with side view of head. 13, Volucella bombylans: side view of head (13a), antenna (13b), and wing extremity (13c). 14, Sericomyia silentis, with head from side (14a) and claw joint of tarsus (14b). 15, Orthoneura nobilis. From Walker (1851, Plate IX), with approximate lengths (head to abdominal tip) indicated.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the genera of Syrphidae (hoverflies). Version: 27th July 2019. delta-intkey.com’.
