British Insects: the Families of Diptera


L. Watson and M. J. Dallwitz


Seashore Flies.

Adult insects. Very small (about 1.5–3 mm long). Antennae 3 segmented (the third segment rounded); ‘modified’; aristate; the arista dorsal (short). The second antennal segment not grooved. Ptilinal suture clearly defined. Post-vertical orbital bristles present (small); convergent. Mouthparts functional. The maxillary palps 1 segmented; porrect. Vibrissae present (but weakly developed). 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; without a sub-apical cell; with a closed anal cell. The anal cell short. The costa with one break (near the end of the upper margin of vein 1). Sub-costa apparent (but weakly developed, visible beyond the base only as a faint fold parallel with vein 1); joining vein 1 more or less where it joins the costa, or terminating blind, or joining vein 1 well short of the costa. Wing vein 6 present; falling short of the wing margin. Wings with the lower calypter much reduced or absent. Tibiae without a dorsal pre-apical bristle. Hind tibiae without strong bristles in the basal 4/5.

Larvae and pupae. The larvae acephalic. The pupae enclosed within a puparium.

Comments. Small to very small greyish or brownish seashore flies.

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

British representation. 10 species in Britain. Genera 3; Pelomyia, Pelomyiella, Tethina.

Illustrations. • Tethina.

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.’.