Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)
Cnemodon Egger; Pipiza p.p.
Adult flies. The flies somewhat muscid-like; black, unmarked; minute to small; 4.5–8 mm long. Wings 5.5–6.25 mm long.
The head about the same width as the thorax. The face entirely dark in ground colour; flat or concave in the region between the antennae and the mouth; without a central knob (covered with long, drooping shaggy hairs). The frons not inflated. The eyes hairy. Antennae relatively short, drooping; with their bases well separated. The third antennal segment ovoid or orbicular (oval or round). The antennal bristle dorsal; simple.
The humeri hairy, and readily visible behind the head. The thorax pubescent without stiff bristles interspersed; plain; without longitudinal stripes. Wings plain; without a conspicuously dark stigma. 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. Vein R without bristles. 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 gently curved to conspicuously bent near the base the base; strongly angled to vein R4+5, so that cell R5 is markedly extended towards the wing tip; not re-entrant. The alula distinct. The hypopleuron exhibiting long hairs on its upper transverse ridge.
The abdomen about the same width as the thorax to narrower than the thorax; narrowly oval, or oblong, or obovate, or more or less fusiform. The male abdomen with 4 visible segments. The abdomen with tergites 2, 3 and 4 all more or less well developed; not contrastingly patterned. The spiracles of the third abdominal segment borne at or near the anterior corner of each side.
Larvae and pupae. The larvae broader posteriorly, tapered to the head; posteriorly blunt and tail-less; flattened; brown, plain; not translucent; dorsally smooth, without projections; mouth with a triangular sclerite on either side; anal segments without lappets. The larvae predatory (on coccids, aphids and other plant bugs associated with elm, poplar and conifers).
Classification. Subfamily Milesiinae; tribe Pipizini.
British representation. 6 species in Britain.
Illustrations. • H. vitripennis: Verrall. • H. heringi (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’.