Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)
Epistrophella, Syrphus p.p., Melangyna p.p.
Adult flies. The flies somewhat Nomada-like, or sphecid wasp-like (cf. Crossocerus quadrimaculatus); black with yellow to whitish markings; small; about 8–9.5 mm long. Wings 5–8 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. The eyes bare. Antennae relatively short, drooping; with their bases well separated. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; simple.
The humeri bare. The thorax pubescent without stiff bristles interspersed; plain; without longitudinal stripes. The scutellum at least partly yellow, or brownish, ferrugineous or tawny. Wings plain; without a conspicuously dark stigma; without black flecks along the hind edges. 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 to slightly diverging from the posterior wing margin. The upper and lower outer marginal cross veins slightly stepped, or strongly stepped (?). The upper outer marginal cross-vein gently curved, or 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 to about the same width as the thorax; narrowly oval, or more or less fusiform, or obovate. The lateral margins of the tergites smoothly rolled over and without beading. The male abdomen with 5 visible segments. The abdomen contrastingly patterned. The tergite patterning involving 3 and 4, or 1, 3, and 4 (tergite 1 sometimes being pale-sided). The colour-patterned tergites marked with whitish to yellow. The tergite patterning confined to tergite 2, or confined to tergite 3, or not confined to one tergite. The interrupted band on tergite 2 more or less reduced to small paired spots. The dorsum of tergite 2 exhibiting a wineglass-shaped black area, or without a wineglass-shaped black area. The tergite bands medianly interrupted; 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 (with serrate lateral margins); posteriorly blunt and tail-less; flattened; green, or not green; species-specifically patterned (variously orange and white, black and white, pinkish brown and black, or greenish grey and white like a bird dropping); with dorsal projections, or dorsally smooth, without projections; mouth with a triangular sclerite on either side; anal segments without lappets. The larvae probably all predatory (consuming a range of arboreal aphids).
General comments. The scutellum with a small black spot on either side..
Classification. Subfamily Syrphinae; tribe Syrphini.
British representation. 3 species in Britain.
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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’.