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

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L. Watson and M. J. Dallwitz

Lejogaster Rondani

Formerly Chrysogaster p.p., Liogaster.

Adult flies. The flies somewhat muscid-like; shiny metallic green, unmarked; minute to small; 5–7 mm long. Wings 4.5–6.5 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); without a central knob; not elongated horizontally into a cone as long as the rest of the head; without tubercles. The eyes bare. Antennae relatively short, drooping; with their bases well separated (seated on a tubercle); black. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; simple (bare).

The humeri hairy, and readily visible behind the head. The thorax bare or finely pubescent?; plain; without longitudinal stripes. The scutellum flat, with a well defined edge. Wings plain (slightly grey); 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. 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 conspicuously bent near the base the base; not re-entrant. The alula distinct.

The abdomen much wider than the thorax to about the same width as the thorax; oval, or ovate (depressed). The male abdomen with 4 visible segments. The abdomen with tergites 2, 3 and 4 all more or less well developed; not contrastingly patterned. Tergites 2–4 equally shiny-metallic all over, without dull patches. 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; brown, plain; without thoracic hooks; mouth without triangular sclerites; anal segments with lappets. The larvae more or less aquatic; saprophagous; in decaying vegetation (and mud, in still and slow-moving water).

Classification. Subfamily Milesiinae; tribe Chrysogastrini.

British representation. 2 species in Britain.

Illustrations. • L. metallina: 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.’.