British Insects: the Families of Diptera

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L. Watson and M. J. Dallwitz

Asilidae

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). • 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.


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. http://delta-intkey.com’.

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