Belongs to: flies

Hornet robber fly Asilus crabroniformis

national priority species

Best time to see: mid Jun to end Jul

Key facts

A large fearsome-looking fly that is becoming very scarce: a national priority species

Habitat: grazed pastures on well-drained soils

Found throughout Wales and southern England, including Essex, but declining throughout its range


Bristly looking flies with a bristly, ginger body, up to 30mm long; black and yellow markings, and long spiny legs;

Dart out from a perch to catch other insects, including grasshoppers, beetles and flies, drinking their body fluids


Adult females lay their eggs on and around animal dung

The grubs enter the soil on hatching and feed on small animals within the dung, such as dung beetle larvae

They spend 3 years in the soil before emerging as adults in the summer, with only a few weeks in which to mate

© Peter Harvey