Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)
Adult flies. The flies somewhat muscid-like; black to bronze; small to medium sized; 7.2–12.5 mm long. Wings 6.25–9.5 mm long.
The head somewhat wider than the thorax to about the same width as the thorax. The face not flat or retreating between antennae and mouth; with a central knob. The eyes dark-spotted, hairy (at least over the upper part). Antennae relatively short, drooping; with their bases approximated (seated on a tubercle); black, or ferruginous (?). The third antennal segment ovoid or orbicular. The antennal bristle dorsal; much longer than the third segment; simple.
The humeri hairy, and readily visible behind the head. The thorax pubescent without stiff bristles interspersed; plain, or patterned to plain; rather inconspicuouly with longitudinal stripes (in E. sepulchralis), or with longitudinal stripes to without longitudinal stripes. The scutellum black. Wings plain (colourless, or tinged brown near the costa); divergent 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 to crossing it at or beyond the middle of the adjoining discal cell (near the middle). Vein R4+5 with 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 gently curved (almost straight); re-entrant to not re-entrant. The alula distinct. The hind femur distally with neither a triangular plate nor a tooth.
The abdomen wider than the thorax to about the same width as the thorax; oval, or oblong, or obovate. The male abdomen with 4 visible segments. The abdomen not conspicuously furry; not contrastingly patterned. The spiracles of the third abdominal segment borne at or near the anterior corner of each side.
Larvae and pupae. The larvae tapering posteriorly; tailed. The anal segment abruptly constricted basally into the long, narrow tail; at least as long as the rest of the body (rat-tailed). The larvae scarcely flattened; plain; without thoracic hooks; mouth without triangular sclerites; anal segments with lappets. The larvae aquatic (rat-tailed maggots); saprophagous, or coprophagous (in decaying vegetation in ponds and marshes, in wet manure, even (E. aeneus) in rotting seaweed in rock pools).
Classification. Subfamily Milesiinae; tribe Eristalini.
British representation. 2 species in Britain.
Illustrations. • E. aeneus and E. sepulchralis: Verrall.
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’.