Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)
Adult flies. The flies bumblebee-like (E. syrphoides, cf. Bombus spp.), or hornet-like (E. erratica, cf. Vespa crabro - i.e., the two species represented being very different in appearance); black marked yellow or tawny (E. erratica), or black and very hairy with pale hair-banded and reddish tailed abdomen (E. syrphoides; medium sized to large; 14–16 mm long. Wings 10.5–12 mm long.
The head much wider than the thorax. The face ground-coloured at least part yellow; not flat or retreating between antennae and mouth. The eyes bare. Antennae relatively short, drooping; with their bases well separated. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; much longer than the third segment; simple.
The humeri bare. The thorax plain; without longitudinal stripes. The scutellum whitish. Wings plain; without black flecks along the hind edges; incumbent and almost parallel in repose, or divergent in repose to 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 with a conspicuous curve projecting into the cell R5 to without a conspicuous curve projecting into the cell R5 (r4+5 markedly dipped); 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 alula distinct. The thoracic squamae without long hairs dorsally. The anterior anepisternum bare.
The abdomen much wider than the thorax, or about the same width as the thorax; broadly, oval, or ovate (almost round). The lateral margins of the tergites exhibiting beaded rims. The male abdomen with 5 visible segments. The abdomen conspicuously furry (E. syrphoides), or not conspicuously furry (E. erratica); contrastingly patterned (but E. rueppellii gingerish-tailed onlt). The patterning attributable to the furry hair coat (E. syrphoides), or not attributable only to the hair coat (E. erratica). The tergite patterning involving (in E erratica) 2, 3, 4, and 5. The colour-patterned tergites marked with in E. erratica yellow. The tergite bands medianly interrupted (the first), or entire (the other two); narrow to wide. The spiracles of the third abdominal segment borne in the middle of each side.
Larvae and pupae. The larvae somewhat tapering anteriorly and posteriorly from the middle; posteriorly blunt and tail-less; more or less flattened (up to 15 mm long, with serrate lateral margins and mid-dorsal projections); blackish, plain (coated in thick black spicules); with dorsal projections; with conspicuous lateral projections; mouth with a triangular sclerite on either side; anal segments without lappets. The larvae predatory (aphidivorous).
General comments. Pubescence of adults abundant, shaggy.
Classification. Subfamily Syrphinae; tribe Syrphini.
British representation. 2 species in Britain.
Illustrations. • wing venation of E. erratica: 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’.