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| Insects of Britain and Ireland: the genera of Syrphidae (hoverflies) |
Adult flies. The flies more or less vespid wasp-like (cf. Dolichovespula and Vespula); black with yellow to tawny markings; medium sized to large; 9–18 mm long. Wings 8.5–12.25 mm long.
The head 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; with tubercles; elongated and tuberculated. The eyes bare. Antennae relatively short, drooping; with their bases approximated (seated on a small tubercle); black. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; much longer than the third segment; simple (bare or pubescent).
The humeri hairy, and readily visible behind the head. The thorax pubescent without stiff bristles interspersed; sometimes fairly inconspicuously patterned; not exhibiting a skull-like figure; with longitudinal stripes (the dorsal stripes whitish to pale yellowish). The scutellum somewhat convex, with undefined edge; brownish, ferrugineous or tawny (or ferrugineous). Wings plain (slightly grey or colourless); without a conspicuously dark stigma; divergent 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 (but almost doing so, the veins converging at the wing margin). The anterior cross vein R-M in cell R5 crossing it at or beyond the middle of the adjoining discal cell (near the middle or somewhat beyond). 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 wider than the thorax, or about the same width as the thorax to narrower than the thorax (wider in the female); oval, or oblong, or obovate. The male abdomen with 4 visible segments. The abdomen contrastingly patterned. The tergite patterning involving 2 and 3 (usually), or 2 to 4. The colour-patterned tergites marked with yellow, or tawny. The tergite patterning not comprising obliquely longitudial marks. The dorsum of tergite 2 exhibiting a wineglass-shaped black area, or without a wineglass-shaped black area. The tergite bands medianly interrupted; wide; incorporating complex figures. The spiracles of the third abdominal segment borne at or near the anterior corner of each side. The pale abdominal markings opaque, or somewhat translucent.
Larvae and pupae. The larvae abruptly 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, with three pairs of fleshy projections before the anal opening). The larvae scarcely flattened; dark brown, plain; without thoracic hooks; mouth without triangular sclerites; anal segments with lappets. The larvae aquatic (rat-tailed maggots); saprophagous, or coprophagous (associated with wet decaying vegetation in mud in ponds, etc., also in farmyard manure and silage).
Classification. Subfamily Milesiinae; tribe Eristalini.
British representation. 5 species in Britain.
Illustrations. • H. pendulus, female (with Syrphus, Helophilus and Xanthogramma). SYRPHIDAE. 1, Syrphus ribesii, female; 2, Scaeva pyrastri, female; 3, Helophilus pendulus, female; 4, Xanthogramma pedissequum, male. Adapted from C.O. Hammond (1968), with names updated. • H. hybridus and H. pendulus: Verrall. • 15 genera (from Walker). 1, Ceriana conopsoides (adventive?), head in side view and extremity of wing. 2, Callicera aurata, with detail of antenna. 3, Microdon mutabilis, antenna and wing. 4, Eumerus strigatus, head in side view and wing. 5, Eristalis tenax: male head from above (5a), female head from the side (5b), and wing of female (5c). 6, Helophilus pendulus: head of male from above (6a) and from the side (6b), and extremity of wing (6c). 7, Merodon clavipes (extinct in Britain): head in side view, and hind leg of male. 8, Tropidia scita, male: head and extremity of wing. 9, Syritta pipiens, male, with head in side view (9a). 10, Xylota sylvarum, male: head (10a), antenna (10b), and base of hind leg showing coxa with a small spine (10d). 11, "Milesia speciosa" (Caliprobola speciosa?): head in side view (11a), wing extremity (11b), and base of hind leg (11c). 12, Criorhina berberina, with side view of head. 13, Volucella bombylans: side view of head (13a), antenna (13b), and wing extremity (13c). 14, Sericomyia silentis, with head from side (14a) and claw joint of tarsus (14b). 15, Orthoneura nobilis. From Walker (1851, Plate IX), with approximate lengths (head to abdominal tip) indicated. • Eristalis fumipennis, Leucozona lucorum, Parhelophilus frutetorum, Spilomyia femorata: Stephens 1846. SYRPHIDAE. 1, Leucozona lucorum (as Syrphus lucorum). 2, Parhelophilus frutetorum (as Helophilus frutetorum). 3, Eristalis fumipennis Stephens (alien - a neotropical species). 4, Spilomyia femorata. From Stephens, 1846. • H. transfugus L. (= ?), with assorted other Syrphidae (adult forms). Syrphidae. 1, Baccha elongata, female; 2, Neoascia podagrica, male; 3 and 4, Melanostoma scalare, male and female respectively; 5, Syritta pipiens, male; 6, Tropidia scita, male; 7 and 8, Sphaerophoria scripta, male and female respectively; 9, Sericomyia silentis, male; 10, Xylota segnis, male; 11, Rhingia camprestris, female; 12, Eupeodes luniger, male; 13, Episyrphus balteatus, female; 14, Helophilus transfugus L., female (= ?); 15, Chrysotoxum cautum, male; 16, Eristalis arbustorum, male. Adapted from C.O. Hammond (Colyer and Hammond, 1968).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the genera of Syrphidae (hoverflies). Version: 27th July 2019. delta-intkey.com’.
