06/24/2016

From ‘Nettles’ to ‘Volcano,’ a Pain Scale for Insect Stings

17:21 minutes

If you’ve ever been bitten by a Bullet Ant, then you’ve experienced a “pure, intense, brilliant pain. Like walking over flaming charcoal with a three-inch nail embedded in your heel.”

Fortunately, you probably have never encountered a Bullet Ant. But Justin O. Schmidt, a biologist at the Southwest Biological Institute has. In fact, he has been bitten and stung close to a thousand times by a wide variety of painful creatures.

Schmidt has gathered all this data in a new book called “The Sting of the Wild.” He is also the creator the Schmidt Sting Pain Index, an entertainingly original way of measuring and describing the relative pain insects inflict on humans and other animals. (Check out Michelle Enemark’s illustration of Schmidt’s findings, courtesy of Atlas Obscura.)

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Schmidt ranks each insect sting on a scale of one to four, with four being the most painful. He also describes each sting with evocative, even poetic, language. The Sweat Bee, for example, which ranks as a one on the pain scale, feels “Light and ephemeral. Almost fruity. A tiny spark has singed a single hair on your arm.”

“I realized that most of us don’t think in terms of numbers. We think in terms of images and art and beauty and song,” Schmidt explains. “That’s the way our species communicates and really understands things. So, I thought, ‘Wouldn’t it be fun to try to apply this as kind of an artistic equivalent?’”

Schmidt says most of the stings he received — and virtually all of the really painful ones — haven been unintentional, because he’s “far too much of a chicken for that.”

“They’ve been in the heat of the battle, like with the Bullet Ant,” he explains. “I was in Brazil, busily digging away and I simply got overwhelmed — dozens of them coming out, very agile and fast. You can’t catch them or dodge them quickly enough and you get stung.”

Schmidt isn’t a crazy masochist. He is trying to understand the evolution of social behavior. Ants, wasps and bees are social creatures that all face a similar problem: how to protect themselves, their brood or their honey, in the case of bees, from predators. He hypothesized that a sting is the only effective defense these creatures have.

“Imagine something 50,000-times bigger than you, like a lion, attacking. How are you going to possibly defend yourself? By scratching, kicking and and yelling? No, you can’t,” Schmidt says. “But if you have the equivalent of a bazooka or a rocket, then you can. And that’s kind of what a sting is.”

Schmidt found pretty much what he had predicted: The more a colony has at risk — that is, the more individuals in the colony and the greater threat of predation — the more pain the insect inflicts and the greater the toxicity of its venom. “If you can do damage, that’s an extra bonus, in addition to making the predator go away,” Schmidt says. “That’s important, because think about pain: It’s really just an indication of damage. It’s not actually damage, and smart predators learn that. Take your local beekeeper, for example. He gets stung all the time and he knows it’s just all in a day’s work, no big deal.”

Schmidt uses the honeybee as a reference point for his scale. Almost everyone has been stung by one, which makes it a handy way to “normalize” a subjective experience. I can’t know how much a honeybee sting hurts you, nor you me; but if we agree that a honeybee sting is a two, then, if we both get stung by something else that hurts more or less than the honeybee sting, the relative difference should be similar.

While all of these insects share a common ability to inflict pain, they all have a unique chemical formula for their venom, Schmidt says. They’re convergent on the same effect — they really hurt — but they’ve gotten there by different routes.

“It’s really almost eerie,” he says. “Honeybees have a peptide called melatin, which is an entirely different chemical structure from wasps. Wasps have kinins, similar to the cardiac stimulant our body naturally makes. Harvester Ants have another totally unrelated peptide. The Bullet Ant is completely unique to science: it has a poneratoxin. So, all these venoms are not related at all chemically, yet they converged on the same solution of making pain.”

Read an excerpt of Schmidt’s book here.

– Adam Wernick (originally published at PRI.org)

Segment Guests

Justin O. Schmidt

Justin O. Schmidt is an entomologist at the Southwest Biological Institute, University of Arizona. He’s author of The Sting of the Wild: The Story of the Man Who Got Stung for Science. He is based in Tucson, Arizona.

Meet the Producer

About Christie Taylor

Christie Taylor is an associate producer for Science Friday. Her day involves diligent research, too many phone calls for an introvert, and asking scientists if they happen to have an audio recording of their research findings.

  • ridahoan

    Did I hear Ira say the pain scale was calibrated by a 3″ nail driven into the foot? Oddly, I’ve had that nail in my foot, and it was quite a bit less painful than the common yellow jacket sting.
    I appreciate the attempt at calibration, as pain scales are tough. I figure they should be logarithmic, because the typical medical scale of 1-10, 10 being the worst imaginable (I think slowly cooked in hot oil) would be so intense that more typical pains would otherwise hardly register.
    But the nurses, they just roll their eyes…

    • Justin Scdhmidt

      You’re right — 1 fire ant sting is a 1 on the pain scale; 10 fire ant stings = 2; 100 stings = 3 …

  • Robert Thomas

    About forty years ago, I was standing on a ladder about three feet off the floor, making modifications to the control electronics of an environmental test chamber that was under construction. This chamber was destined for a Malaysian laboratory where normal industrial current for the three-phase powered fans in the chamber was 416VAC, phase-to-phase. So the fans in the chamber were designed for 416V operation.

    American industrial current is half of that, so our laboratory used a mobile (600 lb) step-up transformer to produce the 416V for the system-under-test fan contactor modules.

    In order to safely work on the control cabinet of this system, I had disconnected the step-up transformer I was using from the overhead AC mains and had coiled up the mains cord (about half-again thee diameter of a garden hose) on top of the transformer housing, leaving the secondary of the transformer connected to the system I was working on. This was normal procedure.

    However, a colleague (nameless forevermore) had decided to make use of a second secondary tap (receptacle) on the utility mobile step-up transformer and in the environment of the lab, didn’t notice that my chamber was also connected to the transformer. He reconnected the transformer’s primary to the overhead mains, while half of my carcass was standing on the step ladder and the other half was inside the command cabinet of my system. Then he walked out of the lab, to have lunch.

    Uh-oh!

    There came a moment when, in order to brace myself, I jammed the palm of my left hand onto the junction block of the incoming three 416V phases of fan mains, leaning all of my weight on the junction block.

    When I woke up, I was sprawled on my back on the concrete lab floor, about ten feet from the ladder I’d been standing on. I had a small cut on my left hand, I believe due to its having flown past a sharp piece of metal in the control cabinet after the muscles of my left arm had violently contracted. I had a black left eye, where my left hand had impacted so hard that I was deeply bruised from my forehead to my jaw. I had bruises on my back and shoulders from hitting the concrete and a lump the size of half a tennis ball on the back of my head. I had no memory of anything after intending to brace myself on the mains block. I’d voided my bladder and vomited.

    Also, every cell of the left side of my body from my knees to my scalp was simultaneously numb and also searing with a diffuse, throbbing, undifferentiated pain of a kind I’d never experienced before and haven’t since. It lasted about twelve hours.

    Where would this stinging sensation fall on the Schmidt scale?

    • Justin Scdhmidt

      Maybe like 100 tarantula hawk stings. Since the pain scale is approximately logarithmic, that would give us a hypothetical 6 (something no insect could do). –JOS

      • Robert Thomas

        Thanks for responding. I was compelled to write by the imp of memory, after hearing electric shock mentioned as a comparable insult.

        Memory of physical pain is puzzling. Is the physical pain value of a remembered incident – a year on, say – a linear function of its intensity at the time of, or immediately after its suffering? Will the sting of one creature fade in memory more quickly than that of another?

        The only incident of pain I can recall as vividly as the one I described above was the sting of a yellow jacket wasp on my eyelid, when I was about five years old. In contrast, the sensation of emergency surgery on my foot, performed without anesthesia a few years ago – the only other such drama I can claim – was way down on the list.

        As for the electric sting, I spent several months unable to force myself to work in that high-energy lab unless I had a the power cord draped over my shoulders, with the disconnected Hubble plug in my peripheral field at all times. Sometimes I had to stare at it hanging there for more than a few seconds, before proceeding.

        That anyone could intentionally expose themselves to the mysterious caprice of biology’s countless belligerencies for the sake of scientific inquiry is evidence of astonishing fortitude. I’m glad it’s you and not me, buddy.

  • I don’t see a yellow jacket on the list other than the baldfaced hornet, but I’m curious how does that rank the same as a honey bee sting? I’ve been stung by honey bees and yet it hurts, but I was also stung by a yellow jacket and I was on my knees crying and screaming profanities from the pain. I was stung on my ankle and the whole area was swollen for about a week. This was about 7 years ago and I still have a little scar to mark the spot. I’m curious to know where a yellow jacket sting would fall on the pain scale, surely higher than the honey bee!

  • Patrick Proctor

    What, no Suzumebachi?

  • Oh thought this was about Coyote Peterson.

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