About Robber Flies

Robber flies are a large family in Diptera with over 600 species in Australia. They are large and conspicuous and can be found resting on branches. They are aggressive predators, able to catch prey on the wing. Asilidae adults attack wasps, bees, dragonflies, grasshoppers, other flies, and some spiders. Asilidae seize their prey in flight and inject their victims with saliva containing neurotoxic and proteolytic enzymes rapidly immobilising prey and liquifying their body contents. All robber flies have a characteristic divot on top of the head, which is located between their especially prominent compound eyes. Larvae are also predacious, feeding on eggs, larvae or other soft-bodied insects.

Zosteria sp. Common Brown Robber Fly. Photo: Robert Whyte