KINGDOM: Animalia | PHYLUM: Arthropoda | CLASS: Insecta | ORDER :Diptera | FAMILY: Asilidae (robber flies)

Most robber flies also have a "bearded" appearance, with fine hairs covering their long, piercing mouthparts.  The most commonly seen robber flies are dark in color, with gray and black bodies, but some common types are orange.  Other species mimic bumble bees, with black and yellow stripes.

Larval robber flies are seldom seen, and are usually found in soil.  They are legless and soft-bodied, and some are fairly large.  A robber fly larva is pictured here at Florida's Featured Creatures page.

Like all true flies, robber flies and their relatives have complete metamorphosis with egg, larval, pupal, and adult stages. The larvae are long and legless and live underground, where they also pupate.  Winged adults are active during warm months.

Robber fly larvae are seldom encountered or photographed.  Pictured below is an illustration by University of Kentucky Entomology graduate student Sarah Colvin (this image was modeled from a preserved specimen).  The Asilidae Home Page also has diagrams of robber fly larvae and pupae here:
http://www.geller-grimm.de/genera16.htm

Robber flies are not normally considered pests.  They will occasionally bite humans, but they are not blood feeders, and will only bite on accident or if provoked.  Because they feed on other insects, robber flies are generally considered beneficial.  However, they do not specialize on pest insects, and sometimes eat other beneficial insects, such as bees or other predators.

BEARDED ROBBER FLIES, BEE KILLERS
GENUS: Efferia, Promachus, others
These robber flies are called "Bearded Robber Flies" because of the many stiff hairs located around the mouthparts.  Some are also called "Bee Killers" because they are often observed catching bumble bees.  Most of these robber flies are over 1" long and have a frightening appearance, but they will only bite if handled carelessly.  They are common in many habitats during the summer in Kentucky, especially along trails and in weedy or agricultural areas.  

HANGING THIEVES, DIOGMITES spp.
GENUS: Diogmites
Below is a robber fly from the Diogmites genus.  These large (1") robber flies are very common in row crops during the summer in Kentucky.  They are sometimes called "hanging thieves" because of their habit of hanging from plants with their long legs.

During the summer and early fall, robber flies are common in Kentucky, especially along woodland trails and in agricultural habitats.  They are always on the move, though, and it may take patience to find one.  Plus, they are strong, quick fliers, so an insect net is needed to capture one. A robber fly will often remain still on a plant or a rock while a photograph is taken, especially if it is not startled.

Robber flies are very popular with insect hobbyists, and there are several websites devoted to them.  Some of the best are listed below:

   Asilidae Homepage
   Herschel Raney's Robber Fly Page
   Giff Beaton's Robber Flies of Georgia and the Southeast
   Roy Beckemeyer's Asilidae Page

Kokopelli, an important figure from Native American folklore, is partly named after "pelli," a word for the "desert robber fly."  Read more about Kokopelli and his relationship with robber flies at the Kokopelli Kave website:
www.melhaven.com/kokopelli/kokostory.htm