Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)
Adult flies. The flies black, with or without yellow markings; minute to small; 4–5 mm long (P. tricincta), or 7–8 mm long (P. latifrons). Wings 3.5–7.25 mm long.
The head wider than the thorax to about the same width as the thorax. The face with the lower half extending smoothly forwards; without a central knob. The eyes hairy, or bare (?). Antennae relatively short, drooping; with their bases well separated; black and tawny. The third antennal segment almost semicircular, with the upper edge straight and the arista near the apex. The antennal bristle thickened, dorsal (but inserted near the upper end of the segment); shorter than the third segment; simple.
The humeri hairy, and readily visible behind the head. The thorax plain; without longitudinal stripes. The scutellum black. Wings plain; 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. Vein R4+5 without a conspicuous curve projecting into the cell R5; without a backwardly projecting, incomplete transverse veinlet. The lower outer marginal vein markedly diverging from the posterior wing margin. The upper and lower outer marginal cross veins strongly stepped. The upper outer marginal cross-vein conspicuously bent well above the base; bent at a sharp angle; not re-entrant. The alula distinct.
The abdomen about the same width as the thorax to narrower than the thorax; very narrowly obovate, or oval, or oblong, or more or less fusiform, or linear (sometimes, almost). The male abdomen with 4 visible segments. The abdomen contrastingly patterned. The tergite patterning involving 2 to 4. The colour-patterned tergites marked with yellow. The tergite bands medianly interrupted and entire, or medianly interrupted, partially interrupted, and entire (the one on tergite 2 interrupted, those on 3 and 4 entire or partially interrupted); narrow to wide. The spiracles of the third abdominal segment borne at or near the anterior corner of each side.
General comments. The life cycle appears to be unknown.
Classification. Subfamily Milesiinae; tribe Pelecocerini.
British representation. 1 species in Britain (P. tricincta). Seemingly confined in the British Isles to southern England.
Illustrations. • P. tricincta: 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’.