| | Insects of Britain and Ireland: the families of Diptera |
Robber-flies.
Life style non-parasitic.
Adult insects. Medium-sized to large; slender-bodied to robustly-built; not stilt-legged (the legs powerful, prehensile, used for grasping the prey). Antennae 3 segmented (third segment not annulated); ‘modified’; with a non-annulated terminal segment; aristate, or not aristate (Laphria); the arista apical. Ocelli present; 3. The top of the head with a marked depression between the eyes, within which the ocellar triangle projects. Eyes rounded, well separated. Mouthparts strong and horny, adapted for piercing (in both sexes). The maxillary palps 1 segmented, or 2 segmented; porrect. Vibrissae absent. Wing veins reaching the margin between the anal cell and the lower fork of vein 3 4. Wings without a sub-apical cell; with a closed anal cell. The anal cell relatively long. Wings with 8 cells between vein 3 and the anal cell. The costa extending around the entire wing. Sub-costa apparent; reaching the costa independently of vein 1. The leading edge veins not noticeably stronger than the rest. Wing vein 3 distally forked. Wing vein 6 present; reaching the wing margin. Wing vein 7 present; falling short of the wing margin. Wings with the lower calypter much reduced or absent. Feet without a triple pad. Predatory (on insects, which are often caught on the wing, and the females often consuming the males).
Larvae and pupae. The larvae terrestrial; saprophagous, or predatory; hemicephalic. The pupae without a puparium.
Comments. Medium to large flies, usually of narrow build, with strong, bristly legs; face below the antennae strongly produced, bearing a ‘moustache’ of hairs and bristles; wings folded over abdomen when at rest. Including some wasp mimics.
Classification. Suborder Brachycera; Division Asilomorpha; Superfamily Asiloidea.
British representation. 29 species in Britain. Genera 15; Asilus, Choerades, Dasypogon, Dioctria, Dysmachus, Eutolmus, Leptarthrus, Leptogaster, Lasiopogon, Machimus, Neoitamus, Neomochtherus, Pamponerus, Philonicus, Rhadiurgus.
Illustrations. • Asilus, Choerades, Dioctria, Leptarthrus (from Walker). 1a and 1b: Choerades marginatus, head in side view and antenna. 2, Asilus crabroniformis, with head from the side (2a), tip of antenna (2b), proboscis (2c) and extremity of tarsus (2d). 3a and 3b, Leptarthrus brevirostris: side view of head, and antenna. 4a, Dioctria oelandica: head and antenna in side view. 5, Leptogaster cylindrica: head in side view (5a), antenna (5b), and hind tarsus (5c). From Walker (1851, Plate II), with approximate length (head to abdominal tip) indicated. • Leptarthrus brevirostris (Slender-legged Robber-fly: B. Ent. 153). • Leptarthrus brevirostris (detail: B. Ent. 153). • Leptarthrus brevirostris (dissections: B. Ent. 153). • Leptarthrus brevirostris (B. Ent. 153, legend+text). • Leptarthrus brevirostris (B. Ent. 153, text cont.). • Pamponerus germanicus: B. Ent. 046. • Pamponerus germanicus: B. Ent. 046, legend+text. • Pamponerus germanicus: B. Ent. 046, text cont.. • Choerades marginatus (Black Robber-fly: B. Ent. 094). • Choerades marginatus: B. Ent. 094, legend+text. • Choerades marginatus: B. Ent. 094, text cont.. • Dasypogon diadema, male (as D. Didema): Stephens 1846. ASILIDAE. Dasypogon diadema (male). British records all date from the early 19th Century, and the species is either alien or extinct there. From Stephens, 1846.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the families of Diptera. Version: 14th April 2022. delta-intkey.com’.
