British Insects: the Families of Diptera


L. Watson and M. J. Dallwitz



Life style parasitic; on especially bees and other Hymenoptera (even as hyperparasites of ichneumonid larvae).

Adult insects. Medium-sized; very robustly-built; winged; stilt-legged, or not stilt-legged. Antennae 3 segmented; ‘modified’; with a non-annulated terminal segment; aristate to not aristate; the arista apical. Ocelli present; 3. Eyes asymmetric, nearly or quite connected above the antennae (in some males), or rounded, well separated. Mouthparts non-piercing (proboscis sometimes very long, sometimes short). The maxillary palps 1 segmented, or 2 segmented; porrect. Wing veins reaching the margin between the anal cell and the lower fork of vein 3 3. Wings with a discal cell; without a sub-apical cell; with a closed anal cell. The anal cell relatively long. Wings with 7 cells between vein 3 and the anal cell. The costa extending around the entire wing. Sub-costa apparent; joining vein 1 more or less where it joins the costa. The leading edge veins not noticeably stronger than the rest. Wing vein 3 distally forked. Wing vein 6 present; reaching the wing margin. Wings with the lower calypter much reduced or absent; patterned, or unpatterned. Feet without a triple pad.

Larvae and pupae. The larvae terrestrial; parasitic; endoparasitic, or ectoparasitic (in or on eggs, larvae or pupae of other insects); hemicephalic. The pupae without a puparium.

Comments. Small to fairly large, bristly and furry, bee-like flies, usually with long thin legs. Wings held open when at rest. The popular name is appropriate both with regard to the general appearance, and the fact that many species parasitise bees.

Classification. Suborder Brachycera; Division Asilomorpha; Superfamily Asiloidea.

British representation. 9 species in Britain. Genera 4; Bombylius, Phthiria, Thyridanthrax, Villa.

Illustrations. • Bombylius major: B. Ent. 613. • Bombylius major: B. Ent. 613, legend+text. • Bombylius major: B. Ent. 613, text cont.. • Bombylius, Lomatia, Phthiria, Villa (from Walker). • Thyridanthrax fenestratus (Beautiful Bee-fly: B. Ent. 009). • Thyridanthrax fenestratus (details: B. Ent. 009). • Thyridanthrax fenestratus B. Ent. 009, legend+text. • Thyridanthrax fenestratus B. Ent. 009, text cont.. • Phthiria pulicaria (Sea-shore Bee-fly: B. Ent. 521). • Phthiria pulicaria: B. Ent. 521, legend+text. • Phthiria pulicaria: B. Ent. 521, text cont.. • Exoprosopa jaccus: as Anthrax pandora, Stephens 1846.

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.’.