Dioctria atricapilla, the violet black-legged robber fly, is a species of robber fly in the subfamily Dasypogoninae. This 9- to 12-millimeter long insect has a wingspan of roughly 7 to 9 mm and short, three-segmented antennae. It's a predatory insect, feeding mainly on smaller flies and predatory hymenopterans. It primarily thrives in grassland, and is seen from May to July.
Habitat and behavior Like all robber flies, the violet black-legged robber fly feed by perching on lower stems of grasses and attack prey as it flies by. The larvae usually grow up in dung piles or decaying organic matter, but they can also be in regular soil.
Courting behavior involves the male leading the courtship dance in front of the female. If she isn't impressed, she'll rapidly move her wings or fly away; otherwise the male will begin copulating.Melin, D. (1923): Contribution to the knowledge of the biology, metamorphosis and distribution of the swedish Asilids. – Zoologiska Bidrag fran Uppsala 8: 317 pp.; Uppsala
Natural status There are 24 locations in the United Kingdom where it's a protected species, mostly in England. It can be found throughout European and east Palearctic grasslands. Identification Difficult to distinguish from other Dioctria. Wolff, Gebel and Geller-Grimm (2021), ( Majer (1997), van den Broek (1979), Stubbs and Drake (2001) all provide keys, descriptions and illustrations. Older works are also useful eg. Seguy (1920) Seguy, E, 1927 Faune de France Faune n° 17 Diptères Asilidae. 188 p., 389 fig Lechevalier editions (Paris: Éditions Faune de France) <ref> Verrall (1909 )(Oldroyd (1969)Oldroyd, H., 1969 Diptera Brachycera: Tabanoidea and Asiloidea (Handbooks for the Identification of British Insects 9/4) Royal Entomological Society, London. Verrall, G. H., 1909 Stratiomyidae and succeeding families of the Diptera Brachycera of Great Britain British flies Volume 5 London : Gurney and Jackson, 1909.BHL Full text with illustrations< Majer,D.M. European Asilidae, in Papp L. & Darvas B. (eds.), Contributions to a manual of Palaearctic Diptera, volume 2 Nematocera and Lower Brachycera. Science Herald, Budapest (Hongrie), 1997, pp.549-567 van den Broek, R., Schulten, A., Wouwen N.(traducteur), Field Guide to the Robberflies of the Netherlands and Belgium, Éditions Jeugdbondsuitgeverij, 2017, 136 pages, (ISBN 9789051070545) Danny Wolff, Markus Gebel and Fritz Geller-Grimm: The Robber Flies of Germany: Discovering - Observing - Identifying . Quelle & Meyer, Wiebelsheim 2018, ISBN 978-3-494-01733-4
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