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

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L. Watson and M. J. Dallwitz

Portevinia Goffe

Cheilosia p.p.

Adult flies. The flies somewhat muscid-like; black with grey spots; small; 8–9 mm long. Wings 6–8.25 mm long.

The head about the same width as the thorax. The face entirely dark in ground colour; with the lower half smoothly extended; without a central knob; not extending below beyond the antennae; not elongated horizontally into a cone as long as the rest of the head. The eyes bare; rimmed along their facial borders for much of the height of the face. Antennae relatively short, drooping; with their bases well separated. The third antennal segment ovoid or orbicular. 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. The scutellum black. 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. The lower outer marginal vein more or less parallel with the posterior wing margin. The upper and lower outer marginal cross veins slightly stepped. The upper outer marginal cross-vein conspicuously bent near the base the base; not re-entrant. The alula distinct.

The abdomen about the same width as the thorax; fairly broadly oval. The male abdomen with 4 visible segments. The abdomen fairly contrastingly patterned. The tergite patterning involving 2 to 4. The colour-patterned tergites marked with whitish, or silvery or greyish. The tergite bands medianly interrupted, or medianly interrupted and entire, or medianly interrupted and partially interrupted (the narrower band on tergite 4 entire or incompletely interrupted); fairly wide. The spiracles of the third abdominal segment borne at or near the anterior corner of each side.

Larvae and pupae. The larvae posteriorly blunt and tail-less; (ventrally? flattened (markedly flattened posteriorly, with a longitudianl anal slit and prolegs absent); cream, plain; without thoracic hooks; mouth without triangular sclerites; anal segments with lappets. The larvae phytophagous; feeding on Alliaceae (recorded tunnelling in Allium ursinum bulbs).

Classification. Subfamily Milesiinae; tribe Cheilosiini.

British representation. 1 species in Britain (P. maculata). British Isles, including western Scotland and Ireland.

Illustrations. • P. maculata: Verrall.

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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.’.