Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)
Adult flies. The flies somewhat muscid-like; patterned whitish to yellowish on the black body; small to medium sized; 9–12 mm long. Wings 7–11.25 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. The frons smooth. The eyes hairy. 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; plain; without longitudinal stripes. The scutellum at least partly yellow, or brownish, ferrugineous or tawny (luteus or brown). Wings pale grey with black veins, patterned (subgenus Leucozona, with a dark central patch), or plain (subgenus Ischyrosyrphus); with a conspicuous dark stigma (this dark brown); 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 slightly stepped to strongly stepped. The upper outer marginal cross-vein conspicuously bent near the base the base; not re-entrant. 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; depressed, oval, or oblong to obovate. The lateral margins of the tergites 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, or 2 and 3, or 2 to 4 (3–4 unmarked or with only small marks). The colour-patterned tergites marked with whitish, or silvery or greyish. The tergite patterning confined to tergite 2 (L. lucorum), or not confined to one tergite. The tergite bands all medianly interrupted (usually), or partially interrupted (tergite 2 in male L. lucorum); narrow, or narrow and wide (the one on tergite 2 usually wider than the others, which are lacking in L. leucorum). 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, or flattened (the flattened lateral margins endowing a sub-triangular cross section); green (e.g., L. laternaria), or not green; translucent, patterned (brownish or greenish, with white or cream chevrons or stripes); translucent; dorsally smooth, without projections; mouth with a triangular sclerite on either side; anal segments without lappets. The larvae predatory (aphidiphorous, on arboreal and ground level species).
General comments. Adults with large jowls, the face with a black middle line.
Classification. Subfamily Syrphinae; tribe Syrphini.
British representation. 3 species in Britain.
Illustrations. • Leucozona lucorum: B. Ent. 753. • Leucozona lucorum: B. Ent. 753, legend+text. • Leucozona lucorum: B. Ent. 753, text cont.. • L. lucorum, male (with Caliprobola, Ferdinandea and Mallota). • L. laternaria: Verrall. • Eristalis fumipennis, Leucozona lucorum, Parhelophilus frutetorum, Spilomyia femorata: Stephens 1846.
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’.