Adults are about 10–12 mm long.
Fine-art photographic collection
Dioctria (Dioctria) atricapilla
A black-legged aerial hunter that launches from grass stems to intercept insects in flight.
About this species
Violet black-legged robberfly
Dioctria (Dioctria) atricapillaMeigen, 1804
Information reviewed17 July 2026
Dioctria atricapilla is a medium-sized European robber fly of grassland, hedgerows and woodland rides. Adults wait on low vegetation and make short, fast attacks on passing flies, beetles and small wasps.
Taxonomy
Animalia · Arthropoda · Insecta · Diptera · Asilidae · Dioctria
Source checked · checked 2026-07-17
EuropeBroad documented European range and representative anchors — not a complete occurrence map.
Europe
Sunny grassland, hedgerows, woodland rides and edges with abundant low perches.
Diurnal; adults are most often seen from late spring to midsummer.
Predatory on other insects, including flies, beetles and small parasitic wasps.
Solitary.
What makes this species remarkable?
It is the only British Dioctria with entirely black legs, while the bright yellow halteres stand out behind the dark wings.
The adult hunts from a perch, firing into the air on a short interception flight and returning to vegetation with captured prey.
Males and females differ conspicuously around the head: males have bluish eyes, while the female face appears golden.