Robber Flies
(Common Name)
(General Category)
Diptera: Asilidae
(Taxonomic Classification)
Many species
(Scientific Name)

Robber fly adult with rollover ID charactersRobber fly adult eclosing with rollover ID characters

Description: Because of their large size and loud buzz when flying, these generalist predators are often confused with horseflies and other biting flies. However, because they are not blood feeders they will not fly around your head or try to land on you, and will only bite if mishandled. When they do alight on foliage, the distinctive bearded face, concavity between the eyes, long legs and usually long tapering abdomen give away their identity. Some are also bee and wasp mimics. Adults are predaceous on flying insects. Larvae are associated with soil or deacaying wood, and are predacious on larvae of other insects.

Identification:  Rollover pictures with mouse for tips on how to identify these predators. Adults: Concavity between eyes, bearded face around beak-like mouthparts. Long legs with fleshy pads at end. Usually long, tapering abdomen. One pair of wings (as in all other flies) with stubby halteres in place of the hind pair. Larvae: Rarely seen because of their location in the soil or rotting wood. They tend to pupate near the soil surface so they can emerge more easily from their pupal cases

Value in Pest Management: Because they feed on insects, they are generally regarded as being beneficial. However, because of their generalist feeding behavior they do not contribute to management of specific pests. They are not sold commercially.

Origin and Distribution:  Native, throughout North America (

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