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.

Nightsnake

Night Snake, Hypsiglena torquata

While out hiking a desert canyon here in Washington County last week, a friend and I happened to find a  Night Snake.  This is the first night snake I have ever come across.  Night Snakes are not uncommon and can be found throughout most of Utah.  Their nocturnal behavior and secrecy make them rarely seen.  These snakes are actually venomous though not very potent, and unlike rattlesnakes their fangs are located in the back of the mouth.  These factors along with its tiny size make this snake harmless to people.  One of the most striking features of these snakes are their eyes.  The vast majority of Utah's snakes have circular pupils, only the Night Snake family and the Rattlesnake family have pupils formed into vertical slits.  This was definatly the highlight of the week.

Nighthawks

Common Nighthawk, Chordeiles minor
On April 21st I noticed four Common Nighthawks flying under the street lamps.  These are the first Nighthawks I've seen this year.  Like me, they are only active when its warm and buggy outside.. but unlike them I don't get to winter in the tropics.  It's great to have them back.  Soon there will be dozens of them around each street lamp.  Life is easy for urban nighthawks.