Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)
Adult flies. The flies Nomada-like; black with yellow markigs; small to medium sized; (6–)8–12 mm long. Wings 5–10 mm long.
The head wider than the thorax to about the same width as the thorax. The face ground-coloured at least part yellow; not flat or retreating between antennae and mouth; with a central knob; not elongated horizontally into a cone as long as the rest of the head. The frons smooth. The eyes bare. Antennae relatively short, drooping; with their bases well separated; black, or black and ferruginous, or black and tawny. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; simple (bare).
The humeri bare. The thorax pubescent without stiff bristles interspersed; plain (but may be paler laterally); without longitudinal stripes. The scutellum aeneous, or brownish, ferrugineous or tawny, or black. Wings plain (colourless to pale grey); without a conspicuously dark stigma (at least sometimes sometimes with a pale brown one); without black flecks along the hind edges; incumbent and almost parallel in repose. 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, or with a conspicuous curve projecting into the cell R5 to without a conspicuous curve projecting into the cell R5 (r4+5 markedly dipped in subgenus Lapposyrphus); without a backwardly projecting, incomplete transverse veinlet. The lower outer marginal vein slightly diverging from the posterior wing margin to more or less parallel with the posterior wing margin. The upper and lower outer marginal cross veins more or less continuous to slightly stepped. The upper outer marginal cross-vein conspicuously bent near the base the base; not re-entrant. The alula distinct. The thoracic squamae without long hairs dorsally. The anterior anepisternum bare.
The abdomen wider than the thorax (often much wider), or about the same width as the thorax; depressed, oval, or obovate. The lateral margins of the tergites exhibiting beaded rims. The abdomen with 5–6 segments apparent. The male abdomen with 5 visible segments. The abdomen contrastingly patterned. The tergite patterning involving 2 to 4, or 2 to 5. The colour-patterned tergites marked with yellow. The interrupted band on tergite 2 more or less reduced to small paired spots, or not reduced to small spots. The dorsum of tergite 2 with golf-club shaped spots, or without golf-club shaped spots; exhibiting a wineglass-shaped black area, or without a wineglass-shaped black area. The dorsum of tergite 3 with a brassiere-shaped pale partially-interrupted band, or with neither a sunglasses-shaped nor a brassiere-shaped partially-interrupted pale band; with a pair of pale marks in the form of a moustache, or not marked in the form of a moustache. The tergite bands medianly interrupted, or partially interrupted, or entire (the first always interrupted, the posterior ones variously interrupted, partially interupted or entire); narrow to wide. The spiracles of the third abdominal segment borne in the middle of each side.
Larvae and pupae. The larvae broader posteriorly, tapered to the head; posteriorly blunt and tail-less; scarcely flattened (that of E. luniger to about 10 mm long); green (or greenish), or not green; longitudinally striped (with a broken dorsal line), or not longitudinally striped; without mid-dorsal and lateral stripes of fat, patterned to plain (greenish or sandy coloured, with or without light or dark marks or mottling); with dorsal projections, or dorsally smooth, without projections; with conspicuous lateral projections, or laterally smooth; mouth with a triangular sclerite on either side; anal segments without lappets. The larvae predatory (mostly aphidivorous on conifer aphids, but some of the commonest species are associated with a wide range of ground-layer species).
Classification. Subfamily Syrphinae; tribe Syrphini.
British representation. 8 species in Britain.
Illustrations. • E. luniger, with assorted other Syrphidae (adult forms).
To view the illustrations with detailed captions, go to the interactive key. This also offers 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.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the genera of Syrphidae (hoverflies). Version: 28th July 2015. delta-intkey.com’.