British Insects: the Families of Diptera


L. Watson and M. J. Dallwitz



Life style parasitic (the females often being notorious blood-suckers), or non-parasitic; on humans and mammals other than humans.

Adult insects. Very small to small; robustly-built (with short, thick legs). Antennae 11 segmented; ‘simple’ (scarcely longer than the head, and bare, the segments not distictly separated); not aristate. Ocelli absent. Eyes asymmetric, nearly or quite connected above the antennae (in males), or rounded, well separated. Mouthparts short, adapted for piercing (in the females), or non-piercing (males). Mandibles present. Mandibles not in the form of long, slender, piercing stylets. The maxillary palps 3–5 segmented; drooping. Vibrissae absent. Thorax without a continuous dorsal suture (i.e., without the V-shaped suture of the Tipulidae). Wing veins reaching the margin 6–8. Wings without a discal cell; without a sub-apical cell; without a closed anal cell. The costa not extending around the entire wing. Sub-costa apparent; reaching the costa independently of vein 1. The leading edge veins markedly stronger than the rest. Wings with the lower calypter much reduced or absent. Parasitic (the females sucking mammalian blood), or neither parasitic nor predatory.

Larvae and pupae. The larvae aquatic (attached to stationary objects in running water only); saprophagous (particles of debris being trapped by the mouth brushes); eucephalic. The pupae without a puparium.

Comments. Small flies with broad wings, short stout bodies and short, thick legs. Both sexes often assembling in clouds around people's heads, especially in sultry weather and near water, the females’ bites being both irritating and capable of transmitting diseases..

Classification. Suborder Nematocera; Division Culicomorpha; Superfamily Chironomoidea.

British representation. 33 species in Britain. Genera 3; Metacnephia, Prosimulium, Simulium.

Illustrations. • Simulium trifasciatum Curtis: B. Ent. 765. • Simulium trifasciatum Curtis: B. Ent. 765, legend+text. • Simulium trifasciatum Curtis: B. Ent. 765, text cont.. • Simulium variegatum (from Walker).

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.’.