British Insects: the Families of Diptera


L. Watson and M. J. Dallwitz



Snipe Flies, Downlooker Flies.

Life style parasitic (some adults being bloodsuckers), or non-parasitic; on when supposedly bloodsucking, humans and mammals other than humans.

Adult insects. Medium-sized to large; slender-bodied; stilt-legged. Antennae 3 segmented (the third segment not annulated); ‘modified’; with a non-annulated terminal segment; aristate; the arista apical, or dorsal. Eyes asymmetric, nearly or quite connected above the antennae (in males), or rounded, well separated. Mouthparts adapted for piercing. The maxillary palps 1 segmented, or 2 segmented; porrect. Wings with a discal cell; without a sub-apical cell; with a closed anal cell, or without a closed anal cell. The anal cell relatively long. The costa extending around the entire wing. Sub-costa apparent; reaching the costa independently of vein 1. The leading edge veins not noticeably stronger than the rest. Wing vein 6 present; reaching the wing margin. Wing vein 7 present; falling short of the wing margin. Wings with the lower calypter much reduced or absent; patterned, or unpatterned. Tibiae at least some spurred. Feet with a triple pad beneath the tarsal claws. Predatory (on other insects), or parasitic (some bloodsuckers, at least among exotic species).

Larvae and pupae. The larvae aquatic (occasionally), or terrestrial; predatory (on other insects and their larvae); hemicephalic. The pupae without a puparium.

Comments. Mostly medium to fairly large, slender, fragile-looking brown and yellow flies, without bristles.Rhagionidae seem to differ morphologically from Athericidae only in subtle and overlapping differences in wing venation.

Classification. Suborder Brachycera; Division Tabanomorpha; Superfamily Tabanoidea.

British representation. 15 species in Britain. Genera 5; Chrysopilus, Ptiolina, Rhagio, Spania, Symphoromyia.

Illustrations. • Rhagio notatus: B. Ent. 705. • Rhagio notatus: B. Ent. 705, legend+text. • Rhagio notatus: B. Ent. 705, text cont.. • 'Leptis diadema', cf. Chrysopilus asiliformis: B. Ent. 713. • 'Leptis diadema', cf. Chrysopilus asiliformis: B. Ent. 713, legend+text. • 'Leptis diadema', cf. Chrysopilus asiliformis: B. Ent. 713, text cont.. • Chrysophilus and Rhagio (from Walker). • Rhagio scolopaceus (Verrall 1909).

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. British insects: the families of Diptera. Version: 1st January 2012.’.