In most Diptera families, the larvae are the carnivorous ones, but that doesn’t apply to this family where the adults are meat eaters and the larvae are vegetarian. There is little physical difference or behavioral difference between a male and female robber fly.
They are known for their hunting prowess and are powerful fliers. They will sit and wait for a meal to fly by then they will chase and catch the insect in flight and suck their insides out while still in flight.
Robber flies have lots and lots of bristles. These are used as a weapon and for defense. Those around the mouth serve to keep the prey in place while they are eaten.
Robber flies oviposit in the ground or on plants. Most of the larval and pupal stages occur in the soil; some develop in plant roots or decaying wood. Many larvae are predaceous in immatures of other insects.