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| Insects of Britain and Ireland: the genera of Syrphidae (hoverflies) |
Cinxia, Sericomya
Adult flies. The flies vespid wasp-like (especially S. silentis, cf. Dolichovespula and Vespula); black with yellow markings; medium sized to large; 12–16 mm long. Wings 9.25–14 mm long.
The head slightly 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; with a central knob. The eyes bare. Antennae relatively short, drooping; with their bases well separated; black, or ferruginous (?). The third antennal segment ovoid or orbicular. The antennal bristle dorsal; much longer than the third segment; plumose.
The humeri hairy, and readily visible behind the head. The thorax pubescent without stiff bristles interspersed; patterned (with a pair of anterior pale spots), or plain (?); without longitudinal stripes. The scutellum brownish, ferrugineous or tawny (ferrugineous). Wings plain (grey, tinted somewhat ferrugineous or tawny basally and along the costa, sometimes clouded brown at the tips); without a conspicuously dark stigma; 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 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 outer marginal cross-vein gently curved; not re-entrant. The alula distinct.
The abdomen wider than the thorax; obovate (in the female), or oval, or obovate (in the male); contrastingly patterned. The tergite patterning involving 2 to 4. The colour-patterned tergites marked with whitish to yellow, or tawny. The tergite bands narrowly medianly interrupted (the bands more or less straight); narrow.
Larvae and pupae. The larvae with the thorax broader than the abdomen, and abruptly tapering posteriorly (the prolegs small and weakly developed - an unusual feature among long-tailed forms); 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; dark brown, plain; without thoracic hooks; mouth without triangular sclerites; anal segments with lappets. The larvae saprophagous; in decaying vegetation (in peaty moorland pools).
Classification. Subfamily Milesiinae; tribe Sericomyiini.
British representation. 2 species in Britain.
Illustrations. • S. lappona and S. silentis: 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. • S. silentis, 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’.
