British Insects: the Families of Diptera


L. Watson and M. J. Dallwitz


Signal Flies (prefered name), Pictured-wing Flies.

Adult insects. Small; robustly-built; winged. The face in lateral view not deeply excavated between the antennae and the edge of the mouth. The back of the head sometimes strongly convave above and convex below. Antennae 3 segmented (the third segment short and rounded or long and thin); ‘modified’; aristate; the arista dorsal (not plumose). The second antennal segment not grooved. Ptilinal suture clearly defined. Ocelli present; 3. Post-vertical orbital bristles present (small). Mouthparts functional (the proboscis very stout); non-piercing. The maxillary palps 1 segmented; porrect. Vibrissae 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, or with a subapical cell to without a sub-apical cell (i.e., sometimes almost closed); with a closed anal cell. The anal cell short. The costa with one break (near the humeral vein). Sub-costa apparent; reaching the costa independently of vein 1. The leading edge veins not noticeably stronger than the rest. Wing vein 1 with hairs on its upper side. Wing vein 4 extending far beyond the end of the first basal cell. Wing vein 6 present; falling short of the wing margin. Wing vein 7 absent. Wings with a well developed lower calypter, or with the lower calypter much reduced or absent; patterned. Tibiae without a dorsal pre-apical bristle. Hind tibiae without strong bristles in the basal 4/5.

Larvae and pupae. The larvae terrestrial; phytophagous, or saprophagous, or predatory; acephalic. The pupae enclosed within a puparium.

Comments. Small flies with patterned wings and a very stout proboscis. Ovipositor sheath not retractile.

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

British representation. 2 species in Britain. Genera 2; Platystoma, Rivellia.

Illustrations. • Platystoma seminationis (Spotted Flat-headed Fly: B. Ent. 505). • Platystoma seminationis (detail: B. Ent. 505). • Platystoma seminationis (dissections: B. Ent. 505). • Platystoma seminationis (B. Ent. 505, legend+text). • Platystoma seminationis (B. Ent. 505, 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.’.