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

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L. Watson and M. J. Dallwitz

Melanogaster Rondani

Chrysogaster p.p.

Adult flies. The flies blackish to dark bronze; minute to small; 5–9 mm long. Wings 5–7 mm long.

The head wider than the thorax to 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 (concave, leading smoothly to the projecting margin of the mouth); with a central knob to without a central knob (the knob sometimes scarcely defined); not elongated horizontally into a cone as long as the rest of the head; with tubercles. The frons markedly inflated. The eyes bare. Antennae relatively short, drooping; with their bases well separated (but seated on a tubercle); black. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; much longer than the third segment; simple (bare).

The humeri hairy, and readily visible behind the head. The thorax pubescent without stiff bristles interspersed; plain (bronze); without longitudinal stripes. The scutellum flat, with a well defined edge; black. Wings plain (grey); without a conspicuously dark stigma; incumbent and almost parallel 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 near the base the base; slightly not re-entrant, or re-entrant. The alula distinct.

The abdomen wider than the thorax to narrower than the thorax (much broader in females); depressed ovate, or oval. The male abdomen with 4 visible segments. The abdomen not contrastingly patterned. Tergites 2–4 dulled dorsally. The spiracles of the third abdominal segment borne at or near the anterior corner of each side.

Larvae and pupae. The larvae tapering posteriorly; tailed. The anal segment tapered gradually to the spiracular process (not rat-tailed). The larvae scarcely flattened; mouth without triangular sclerites; anal segments with lappets. The larvae aquatic (reported to use their anal segments to probe submerged plant roots and shoots for air); phytophagous, or saprophagous (? - associated with aquatic plants).

General comments. No adequate description of the larva located.

Classification. Subfamily Milesiinae; tribe Chrysogastrini.

British representation. 2 species in Britain.

Illustrations. • M. hirtella: 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.’.