Red-footed Cannibal Fly

 

I got the opportunity to go afield last Sunday (August 27, 2023) with Iris Copen and Shaun Pogacnik, two of the Midwest's best field botanists. We hit remote sites in Jackson, Lawrence, and Pike counties in southern Ohio. Plants were the main quarry, and we saw scads of cool vegetable matter, highlighted by a new state record of a particularly beautiful species, the Maryland Meadow-beauty (Rhexia mariana). Iris and Shaun had discovered it a few days prior. I'll write about that one and share photos in a later post.

We didn't ignore bugs (one should never ignore bugs) on this epic botanical foray. This beast pictured above was an entomological highlight: the Red-footed Cannibal Fly (Promachus rufipes). Savage and capable hunters, cannibal flies spot prey flying by from their perches, roar out with a loud buzzing flight, and overtake and grab the victim in an Iron Maiden death grasp with those spiny legs. I believe the one in the photo has captured a bumblebee (Bombus sp.) It then pierces the prey with a syringe-like proboscis, injecting a powerful neurotoxin that causes near instant paralysis. Other chemicals rapidly dissolve the prey's innards, which the cannibal fly sucks out through its proboscis like a ghoulish milk shake.

These big robber flies are effective predators and can take down surprisingly large prey. CLICK HERE for an apparent case of one that captured a Ruby-throated Hummingbird.

In the photo above, a pair of Red-footed Cannibal Flies mate on a Virginia Pine branch. They can actually fly when in tandem like this, and the spectacle of nearly six inches of loudly buzzing bugs shooting past one's head is enough to make an entomophobe faint.

We felt fortunate to see a number of cannibal flies on this day. Interestingly, perhaps, they were all this species. There is a very similar species, Promachus hinei, which has redder legs and it seems to be widespread and at least locally common. But all of the cannibal flies we could see well enough to identify were P. rufipes and nary a hinei was to be seen.

Red-footed Cannibal Fly!

The Slender Ladies'-tresses, Spiranthes lacera, is one of our smallest orchid species, but always a star. Yesterday, I led a group on a trip to explore some interesting natural areas in southeastern Ohio. One of our stops was a very interesting oak barrens that is regularly subjected to controlled burns. Plant life in this locale is spectacular, and includes one of the rarest plants in Ohio. I hope to write more about that species soon. On the hike back to see the rarity, we stopped to admire this diminutive ladies'-tress, which was a "life" plant for most of the group.

But a fly, of all things, ended up stealing the show. Lisa Brohl spotted a large, strange-looking insect and drew my attention to it. Yes! Even from afar, it was instantly identifiable as the gargantuan, death-dealing Red-footed Cannibal Fly, Promachus hinei. Those of us who were bringing up the rear of the group (I'm always last!) were treated to the spectacle of one of our most ferocious insects.

We move in...

The cannibal fly was semi-cooperative, and after a bit of sneaking about, we were able to draw quite near. It was preoccupied. The animal had snared a large bumblebee, and has it in its clutches. Now that's tough! Very little is safe around a Red-footed Cannibal Fly. They, obviously, are not even deterred by insects that can give a nasty sting. This isn't the first time I've seen one with a bumblebee, either.

A cannibal fly on the hunt parks itself a leaf or branch with a good view of the surrounding landscape. When an appropriate victim - usually a large insect - flies into view, the cannibal fly launches itself and proceeds apace towards the prey. There is nothing particularly deft or agile about the operation. Accompanied by a loud buzzing drone, the fly hurtles clumsily but rapidly at the victim, and rams it in midair. Once the prey is met, the cannibal fly enfolds it with powerful spine-covered legs; an entomological iron maiden from which there is no escape.

The coup de grace is then administered. The fly's proboscis is a sturdy tube much like a hypodermic syringe, and it is rammed deeply into the doomed victim. Acidlike substances are piped in, which aid in dissolving the innards, and the liquefied goop is then sucked back out leaving little more than a dried husk. After a well deserved rest, the cannibal fly prepares for the next hunt.

This insect might be thought of as the Peregrine Falcon of the insect world. They are high-end predators, and from my experience are not very common. I see but a few each year, and when I do, the cannibal fly is invariably in some high quality habitat such as a prairie remnant or other open habitat of rich botanical diversity. Lots of native plant diversity breeds lots of pollinating insects, which in turn spawn a fabulous assemblage of predators, and of this latter group, the Red-footed Cannibal Fly is hard to top.

Red-footed Cannibal Fly

What a week of travels this has been. Just returned from the shores of Lake Erie - Ohio's north coast - and I'm off to Adams County at the crack of dawn tomorrow. The latter is an Ohio River county and about as far away as one can get in from Lake Erie and Kelleys Island and remain in Ohio.

Anyway, it must be a good year for robber flies. These predatory carnivores are the falcons of the fly world, and even the smallest species are impressive. The giant ones are downright scary. I've gotten several photos of the following brute sent to me in the past few weeks. People understandably want to know the name of such a barbaric looking insect. In case you, too, have seen the awesome red-footed cannibal fly, then perhaps this post will be of help to you.

A female red-footed cannibal fly, Promachus hinei, lurks on walnut foliage. I found her this morning at the Blue Heron Reserve in Sandusky County. She had just mated, and the sight of two of the beasts coupled and flying about was impressive to say the least. Or scary, depending on your perspective. I was unable to get the lens on them in time to document their amorous behavior. But after all was done and the male went off to smoke a cigarette or whatever it is that male cannibal flies do in the immediate aftermath of a conquest, she settled nicely.

Cannibal flies are not daunted by much. I see a few of them most years and always try for photos. As often as not, the bug will allow very close approach. I was using my little Panasonic Lumix for these shots and had the lens as close it would go - maybe within a foot or two.

Inscrutable and intimidating, I suspect that whatever genes cause fear are absent in red-footed cannibal flies. These things bring down remarkably large prey; animals that few if any other predatory  insects could capture. I have seen photos of cannibal flies with annual cicadas. Hummingbirds. Large bumblebees. Other big robber flies. The cannibal fly sits in wait, as this one is doing, and waits for prey to wander by. Nothing that isn't at least twice the fly's size is safe, if the fly is hungry and wants a meal.

Like other robber flies, the cannibal fly dispatches its victim with a jab from its syringelike proboscis. Toxins rapidly paralyze the prey, and other chemicals rapidly turn the hapless creature's insides to slush. The fearsome cannibal fly then sucks its insides out, just as you would slurp up a milkshake through a drinking straw.

Be thankful these insects aren't the size of Sandhill Cranes.

Red-footed Cannibal Fly

A bumble bee, genus Bombus. Mild-mannered but large and somewhat intimidating, most critters give them a wide berth. They can sting, you know. So, for the most part these big fuzzy bees bumble about the flower patch with impunity, not probably giving a lot of thought to danger. After all, who is going to tussle with one of these black and yellow behemoths?

This. It's a Red-footed Cannibal Fly, Promachus hinei, and there are few insects higher up on the predator chain. As you can see, it has captured a bumble bee and is enjoying the fruits of its kill. If these things ever evolve to the size of Trumpeter Swans, I pity the humanoids that walk the earth in that grim future landscape.

The consumate killer, this robber fly misses nothing and seemingly can take out nearly any other insect. I once saw an amazing photo of one that had captured an Eastern Pondhawk dragonfly. Well, pondhawks are pretty much the goshawks of the dragonfly world, routinely snagging and eating other dragonflies up to their own size if not larger. For a fly, of all things, to take one out is amazing.

While exploring some Adams County prairies last Sunday, our group encountered several cannibal flies, but none so cool as this one. It was something to watch it lug that bee around, and after a bit of patient stalking, I was able to get my lens within a foot or so. It's perched on a Little Bluestem grass, Schizachyrium scoparium.

The world of flies is indeed wacky, wonderful, and diverse in the extreme. They can be annoying, such as the common houseflies that haunt your garbage. Some are mimics extraordinaire, looking all the world like bees or wasps. Many are harmless pollinators of flowers. Some are dangerous and insidious death-dealers - parasitoids - laying their eggs on other insect hosts which will eventually be eaten alive by the larvae.

Then there is this - the Red-footed Cannibal Fly. It gets my vote as King of Fly World, at least in these parts.