Obscure Utah Fauna of the Week: Robber Fly

Robber Fly feeding on a small beetle

Robber Fly does not refer to a single species, rather an entire family of thieving bastards called Asilidae.  These flies are typically drab colored, often covered in hair, and have elongated bodies.  Their name derives form their habit of stealing prey such as spiders from hunting wasps and other insects.  Pilfering however, is not the only way these flies can score a meal, they are also expert hunters.  Streamlined and powerful fliers they have no trouble taking on butterflies, tough-shelled beetles, or even wasps.  Asilids hunt by sitting on open ground or on an exposed twig where they have clear views to dash out and catch their prey.  Biting mouthparts make short work of even the toughest meals, and can inflict a painful bite to carless entomologists.  All in all these are some of my favorite flies and I can't imagine a world (or the grill of my truck) without them.