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

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L. Watson and M. J. Dallwitz

Eristalis Latreille

Elophilus, Eristaloides, Eristalomya, Eristalomyia, Helophilus Leach, Tubifera.

Adult flies. The flies variously bumblebee-like (E. intricarius), or hivebee-like (E. tenax, E. pertinax, E.rupium), or resembling a mining bee, or resembling Colletes, or vespid wasp-like, or cimbicid sawfly-like, or muscid-like; black to dark brownish, variously unmarked or conspicuously marked with tawny or yellow; medium sized to large; 10.5–16 mm long. Wings 6.5–13 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 not spotted, hairy. Antennae relatively short, drooping; with their bases approximated (seated on a tubercle); black, or ferruginous, or black and ferruginous, or black and tawny. 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; basally plumose, or simple.

The humeri hairy, and readily visible behind the head. The thorax pubescent without stiff bristles interspersed; plain; without longitudinal stripes. The scutellum at least partly yellow, or brownish, ferrugineous or tawny, or whitish (often ferrugineous or tawny, not black). Wings patterned to plain (colourless, or tinged brown near the costa, sometimes with a large dark central patch); divergent in repose, or divergent in repose to incumbent and almost parallel in repose. Wing veins R2+3 and R4+5 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 (before or 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); not re-entrant. The alula distinct. The hind femur distally with neither a triangular plate nor a tooth.

The abdomen usually markedly wider than the thorax (anteriorly); obovate. The male abdomen with 4 visible segments. The abdomen conspicuously furry; contrastingly patterned (but then sometimes pale- to ginger-tailed only, e.g., the ginger bumblebee-like E. intricarius), or not contrastingly patterned. The patterning variously attributable to the furry hair coat, or not attributable only to the hair coat. The tergite patterning involving 2 (only, sometimes), or 2 and 3. The colour-patterned tergites marked with tawny. The tergite patterning confined to tergite 2, 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 tergite bands widely medianly interrupted (the components sometimes complexly shaped). 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 maggots). The larvae scarcely flattened; pallid, plain; without thoracic hooks; mouth without triangular sclerites; anal segments with lappets. The larvae more or less aquatic to semi-aquatic; saprophagous, or saprophagous and coprophagous (in decaying vegetation in organically rich ponds and ditches, also farmyard manure and silage).

Classification. Subfamily Milesiinae; tribe Eristalini.

British representation. 10 species in Britain.

Illustrations. • Eristalis cryptarum (Beautiful Hover-Fly: B. Ent. 432). • Eristalis cryptarum: B. Ent. 432, legend+text. • Eristalis cryptarum: B. Ent. 432, text cont.. • E. arbustorum, E. horticola, E. rupium, E. tenax: Verrall. • E. tenax, female, with Brachypalpoides, Criorhina and Xylota. • 15 genera (from Walker). • Eristalis fumipennis, Leucozona lucorum, Parhelophilus frutetorum, Spilomyia femorata: Stephens 1846. • E. arbustorum, with assorted other Syrphidae (adult forms).

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.’.