Robber Fly

Efferia ? sp.

Efferia robber fly photo © by Mike Plagens

Observed at Mesquite Wash, Mazatzal Mts. foothills, Maricopa Co., Arizona in August 2009.

Asilidae -- Robber Fly Family

Efferia robber fly photo © by Mike Plagens

Observed in the Rainbow Valley, western Maricopa County, Arizona, USA. August 2010. A prey item is no longer identifiable.

In the miniature world of insects, asilids (robber flies) are top predators. Each of the six legs are equipped with sharp, talon-like tarsal claws. The mouthparts include a stout beak-like proboscis that delivers the fatal stab to prey. Indeed, like miniature falcons or accipiters these flies capture flying insect prey on the wing holding them secure with their tarsal claws and delivering fatal bites with the proboscis. There are many species of robber flies common in the Sonoran Desert. Many perch on prominent lookouts such as a boulder or a piece of wood along washes. They sally out and capture a passing insect, often larger than themselves. Some species resemble bees and actually prey on bees.

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Copyright Michael J. Plagens, page created 4 Sept. 2009,
updated 7 Aug. 2017.