Adult robber flies are predators of other flying insects. They attack a variety of insects, even those that are larger than themselves.
They insert their short but strong proboscis into the insects to suck their body fluids. Some of the larger species can give a painful bite if handled.
Adults are common in dry, open and sunny places. The larvae are found in soil, decaying wood or fallen leaves where they are predaceous on the eggs, larvae, and pupae of other insects.
Robber flies are small to very large sized, hairy with usually a long slender abdomen. The legs are long and spiny, the lower part of the face or sometimes the entire face is covered with dense bristles, and the top of the head is excavated. Most are dark colored but some are black and yellow and look like bees.