British Insects: the Families of Diptera


L. Watson and M. J. Dallwitz



Adult insects. Very small to small. The face in lateral view not deeply excavated between the antennae and the edge of the mouth. Antennae 3 segmented; ‘modified’; aristate; the arista apical to dorsal (subapical, pubescent). The second antennal segment not grooved. The second antennal segment when viewed from the outside with a triangular projection extending partway over the third and often with an upper and a lower bristle. The third segment not elongated (rounded). Ptilinal suture clearly defined. Lower orbital bristles present. Post-vertical orbital bristles present; divergent. Mouthparts functional. The maxillary palps 1 segmented; porrect. Vibrissae present. Thorax without a continuous dorsal suture; without well defined posterior calli. Wing venation complete, in the sense of exhibiting 1st and 2nd basal, anal and discal cells. Wings with a discal cell; with a closed anal cell. The anal cell short. The costa with one break (near the end of the sub-costa). Sub-costa apparent; reaching the costa independently of vein 1. Wing vein 6 present; falling short of the wing margin. Wings with the lower calypter much reduced or absent. Tibiae with a dorsal pre-apical bristle, or without a dorsal pre-apical bristle. Hind tibiae without strong bristles in the basal 4/5.

Larvae and pupae. The larvae terrestrial; saprophagous, or mycophagous (in rotting wood); acephalic. The pupae enclosed within a puparium.

Comments. Very small to small flies, often associated with rotting wood and fungi.

Classification. Suborder Brachycera; Division Muscomorpha Schizophora Acalyptratae; Superfamily Opomyzoidea.

British representation. 10 species in Britain. Genera 4; Clusia, Clusiodes, Heteromeringia, Paraclusia.

Illustrations. • Clusia flava (from Walker). See notes for legend.

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.’.