British Insects: the Families of Diptera


L. Watson and M. J. Dallwitz


Including Helcomyzidae.

Sea-shore Flies.

Life style non-parasitic.

Adult insects. The face in lateral view deeply excavated between the antennae and the edge of the mouth, or not deeply excavated between the antennae and the edge of the mouth (Helcomyzidae). Antennae 2 segmented, or 3 segmented; ‘modified’; aristate; the arista dorsal (not plumose, very short in Helcomyza). The second antennal segment not grooved. Ptilinal suture clearly defined. Ocelli present; 3. Post-vertical orbital bristles present; parallel, or divergent. Mouthparts functional. The maxillary palps 1 segmented; porrect. Vibrissae present, or absent. 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 (large by comparison with related genera, but extending less than a third of the way to the wing margin, though). The costa unbroken. Sub-costa apparent; reaching the costa independently of vein 1. Wings without a ‘vena spuria’. Wing vein 6 present; reaching the wing margin. Wings with the lower calypter much reduced or absent; patterned, or unpatterned. Tibiae with a dorsal pre-apical bristle. Hind tibiae without strong bristles in the basal 4/5.

Larvae and pupae. The larvae aquatic (e.g. Helcomyza ustulata, which live in dislodged seaweed and are inundated by each tide), or terrestrial; saprophagous, or coprophagous, or mycophagous; acephalic. The pupae enclosed within a puparium.

Comments. Yellowish or reddish brown flies of moist places, associated with rotting seaweed, putrifying matter or rotting fungi. Wings very large, much longer than the abdomen.

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

British representation. 6 species in Britain. Genera 5; Dryomyza, Neuroctena, Helcomyza, Heterocheila, Malacomyia.

Illustrations. • Dryomyza and Helcomyza (from Walker). • Helcomyza ustulata (Original genus and species descriptions. Sea-shore Helcomyza: B. Ent. 066). • Helcomyza ustulata (detail: B. Ent. 066). • Helcomyza ustulata (dissections: B. Ent. 066). • Helcomyza ustulata (B. Ent. 066, legend+text). • Helcomyza ustulata (B. Ent. 066, text cont.).

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.’.