Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)

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L. Watson and M. J. Dallwitz

Epistrophe Walker

Formerly Syrphus p.p.

Adult flies. The flies Nomada-like; mostly black with yellow markings; small to medium sized; (8–)10–12(–14) mm long. Wings 6–12.25 mm long.

The head scarcely to considerably 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. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; about as long as the third segment to much longer than the third segment; simple (bare).

The humeri bare. The thorax pubescent without stiff bristles interspersed; patterned (with yellow); with longitudinal stripes to without longitudinal stripes. The thoracic striping when manifest, lateral only; exhibiting sharply defined, yellow lateral lines, or without well defined lateral lines. The scutellum tawny in E. grossulariae. Wings plain (colourless or with a brown stigma); with a conspicuous dark stigma to without a conspicuously dark stigma; 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; without a backwardly projecting, incomplete transverse veinlet. The lower outer marginal vein more or less parallel with the posterior wing margin. The upper and lower outer marginal cross veins more or less continuous. 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; depressed, oval, or oblong, or obovate, or more or less fusiform (often more or less angled at the widest part). The lateral margins of the tergites exhibiting beaded rims to smoothly rolled over and without beading. The abdomen with 5–6 segments apparent. The male abdomen with 5 visible segments. The abdomen contrastingly patterned. The tergite patterning involving 2 (only, in typical male E. elegans), or 2 to 3, or 2 to 4, or 2 to 5. The colour-patterned tergites marked with yellow to tawny. The tergite patterning confined to tergite 2 (in typical male E. elegans), or not confined to one tergite. The dorsum of tergite 2 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. The tergite bands medianly interrupted and entire, or medianly interrupted and partially interrupted, 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, or tapering anteriorly and posteriorly from the middle; posteriorly blunt and tail-less; very flattened (with non-serrate lateral margins); green; longitudinally striped; patterned (green, with a pale mid-dorsal stripe); mouth with a triangular sclerite on either side; anal segments without lappets. The larvae predatory (probably aphidivorous, found mainly on trees and shrubs).

Classification. Subfamily Syrphinae; tribe Syrphini.

British representation. 6 species in Britain.

Illustrations. • E. grossulariae and E. nitidicollis: Verrall. • E. elegans: Verrall. • E. grossulariae, Melangyna barbifrons, Syrphus ribesii and Syrphus torvus (thoracic squamae).

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.’.