Asilidae - Robber-flies



BRACHYCERA, Asilomorpha, Asiloidea

Number of British species: 29

Size: M-L

Difficulty: 1-2

Scheme: Covered by the Larger-Brachycera recording scheme


Small (3 mm) to very large (50 mm), but generally medium sized to large (8-20 mm) flies, varying in shape from long and slender to short and stout. The colour of the body and pubescence are variable from dark metallic lustrous to paler, with orange or yellow markings on body and wings, or resembling bees and wasps. Head dorsally concave in between the large, dichoptic eyes; ocelli implanted on an elevation between the eyes; antenna variable, third segment elongate, usually followed by 1 or 2 segment(s) which may, or may not, constitute an arista or style; face relatively long and nearly always with a distinct facial knob bearing long bristles, named the mystax or beard; mouthparts powerful and piercing. Wing usually clear, in some cases completely or partially tinged or darkened; cell m3 and cell cup open or closed. Legs long and powerful, often armed with strong bristles; tibiae with apical bristles or spurs; empodium bristle-like or absent.


The larvae live in the soil and in decaying wood; as far as known they largely feed on the larvae of other insects. The adults are predators as well. Most species prefer open, sunny habitats and are mainly active during the warmest part of the day. They are able fliers that catch their prey - mainly other insects - on the wing. They are often seen on lookout posts like walls, branches and leaves, or on the ground, surveying their surroundings for possible prey flying by.


families/brachycera/old_brachycera/asilidae.txt · Last modified: 2008/05/24 17:01 (external edit)     Back to top
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