Robber Fly Cannibal

Robberfly Promachus rufipesIt was a beautiful fall day in Georgia when a hummingbird startled me by buzzing my head. We had a colony of hummingbirds as we regularly fed them but they never buzzed my head unless I was standing near their hummingbird feeder, which was a distance away. The hummingbird buzzed me, hovered in mid-air and then flew off.

Seconds later a large insect buzzed me and then landed on a nearby leaf. It was a big, scary looking bug and I ran indoors to grab the camera fully not expecting him to still be there, but he was. I snapped a few photos of the bug and then looked him up on the internet. I tried a search for horsefly and elongated fly with no luck. Long striped fly hit paydirt, however, and I was able to identify the bug. I wish I’d killed him for he may have been what put the hummingbird into a panic.

The scary bug was a Robber Fly, also known as a Giant Robberfly, Bee Panther or Red-footed Cannibalfly. The latter gave me the willies. Nothing good could come of a bug sporting the name Cannibal and I was pretty certain I’d identified him correctly. His scientific name is Promachus rufipes.

Robber Flies come in a variety of shapes and colors, some resembling fuzzy black and yellow bumblebees and others, like ours, with elongated bodies. They have bearded faces with hairs that cover their long, piercing mouthparts. Robber Flies also have stout, spiny legs for grabbing and holding onto their prey. They perch on plants awaiting their next meal to fly by and then take off to capture their prey in mid-air. They may also attack from above, targeting insects who are themselves resting on a leaf or feeding from flowers such as honeybees, thereby earning the common name Bee Panther.

Promachus rufipes RobberflyThey feed on bees and wasps, flies and dragonflies, beetles, grasshoppers, and other Robber Flies. Apparently, they’ve also been known to attack and kill hummingbirds. That is why I wish I’d killed it, to protect our hummingbird colony.

The powerful legs of the Robber Fly latch onto their prey while their proboscis stabs into the victim, injecting it with a paralyzing enzyme. Robber Fly saliva contains both a neurotoxin and enzymes which liquify the innards of their prey fairly quickly. Then the Robber Fly sucks out the liquified meal as if through a straw.

Some species of Robber Flies are considered beneficial insects, while others have the potential to harm bumblebees and hummingbirds making them undesirable. While they rarely attack humans, they can inflict quite a nasty bite if provoked causing pain, swelling and redness at the bite site. Predators of the Robber Fly include other Robber Flies (hence the name Cannibalfly), spiders, birds, praying mantis bugs, and assassin bugs.

The Red-footed Cannibalfly that we’d encountered is a Robber Fly which is common in the Southeast from July through October.

The robber fly cannibalfly is featured in the book “Over the Hummingbird’s Rainbow: An Acre of America Backyard Nature Series” which is an expanded version of the nature blog with photos and stories. These books are all available on Kindle. The adult series is also available in paperback.

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