By Karen Menard

A bee fly with a dusting of pollen? How about a flying ant with a side of nectar?  Cold-blooded brutes powered by wings and a thorax built like a dump truck, lurk quietly in the shadows seeking their next insect meal.

And, any bug will do. These superstar predators with voracious appetites are called robber flies, and they aren’t picky eaters—arthropod stew is always on the menu. Their day begins and ends with “fast food” hijackings in mid-air, and their catch pays the ultimate price. 

Speedy seizures are a specialty, and their “take out” preferences occur in a variety of ways depending on the species.  One popular mid-air method of dispatch involves darting and detaining directly from a perch. Another strategy requires the implementation of a cat-like pounce and plunder maneuver from ground level. And, lastly, the sneak up and snag attack always surprises motionless, unsuspecting prey.

Aerial assaults on other insects come easy for robber flies because they possess some amazing adaptations.  Their eyesight is similarly as sharp as a dragonfly which can detect prey at distances close to 15 times greater than a human.  Robber flies view their prey through compound eyes enhanced with numerous lenses of varying sizes, enabling a very high resolution view of the world.  Their thorax and legs are packed with strong muscles for powerful flight and agile maneuvers. And, bristly hairs that appear similar to a mustache and beard, actually serve as protection against potential injury from larger, flailing prey.

One of their most interesting attributes are modified, beak-like mouthparts that also couple as convenient tools for efficiently completing their daily feeding tasks.  Their mouthpart, like a dagger of sorts, delivers a quick stab first; then, as a needle administering a shot-- injects neurotoxins and digestive enzymes, quieting their victim.  Enzymes aid in the completion of the process, transforming the insides into a gooey concoction of liquefied bug stew. For the final step in their cuisine preparation, an appendage called a hypopharynx acts as a straw to slurp up the stew.

These majestic insects possess impressive flight, hunting and feeding finesse. As masters of these skills, they are fun to seek out and observe along a trail or even in your own backyard during the spring, summer or fall. Keep in mind that there are many different types of robber flies that live in various habitats throughout northwest Ohio, filling an important niche as ecosystem components--keeping other insect populations in check.

View the slide show below for a glimpse into the beautiful diversity of robber flies found throughout our different Metropark ecosystems.                                                                                                         

Did you know? There are about 1,000 species of robber flies native to North America. “Hanging thief” robber flies are known for their unique way of feeding on their prey—hanging from one leg with their catch cradled below.

Many thanks to Rick Nirschl, who has provided some excellent photos of robber flies in the Metroparks.

Above photo: Stock photo