Thursday, August 28, 2014

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.


Gaia Gardener: said...

I'm becoming a little more adept at finding robber flies in the landscape around our house - they often make a fairly distinctive drone that gives them away when they fly. They are great predators! The ones I'm currently enjoying are the hanging thieves - it amazes me how well they can grip with just one foot while feeding on insects that are usually at least their own size. I enjoy your posts - you've always got great photos and interesting information to impart. Cynthia

Cameron Svoboda said...

Promachus rufipes, you mean? I'm not an expert, but I thought Red-footed Cannibalfly was the common name of rufipes, not hinei.