Stung for Science: Meet the Man Who Measures Pain
University of Arizona professor Justin Schmidt
Credit: Johns Hopkins University Press

Been stung by a bug? Well, Justin Schmidt feels your pain. No, seriously — no matter what type of insect stung you, Schmidt surely has been stung by it, too, and has documented that pain.

An entomologist at the University of Arizona, Schmidt studies the evolution and purpose of the stings that ants, bees and wasps can deliver, and the range of human pain these stings can cause. In doing that work, Schmidt has been stung — accidentally or purposely, in the name of science — more than a thousand times by nearly 100 different kinds of stinging insects.

Now, he recounts his most painful memories in a book published this month called "The Sting of the Wild" (Johns Hopkins University Press, 2016). The book includes the famed Schmidt sting pain index, akin to the Scoville scale, a subjective measure of chili pepper heat.

Schmidt's pain index, referenced in the movie "Ant Man," is a testament to the researcher's literal blood, sweat and tears. Entries range from a report on the painless sting of the club-horned wasp, which Schmidt describes as a "paper clip fall[ing] on your bare foot," to a description of the sting of the fearsome tarantula hawk wasp as "blinding, fierce, shockingly electric." [5 Surprising Facts About Pain]

Comprising mostly stories from the author's life, Schmidt's book is an evolution lesson in the guise of humorous misadventures among ornery critters with names like the cow killer and warrior wasp. None are bigger than an inch or two long (2.54 to 5.08 centimeters), but boy, do some of them pack a punch in their stings.

The question that Schmidt has asked for more than 30 years as a researcher, and the one he poses in his book, is why? Why does one ant or bee species have a mild sting and another of about the same size have a sting that delivers mind-numbing pain?

The answer, as you can imagine, is complex. But Schmidt has been stung enough times by hymenoptera — an order of insects that includes sawflies, wasps, bees and ants — to develop a hypothesis: Those with the most to lose have the nastiest stings.

The first thing to know is that the stinger is an appendage that evolved to plug eggs into hard surfaces, such as tree bark. This is why only the female of any given hymenoptera species can sting. Over countless millennia, this appendage developed into a stinger that can deliver venom as well as eggs. Yet the venom varies greatly in its pain potency. Enter Schmidt's explanation. [In Images: The Insect Family Tree]

The honeybee has a painful sting. These bees live in colonies and have stores of honey, which many animals desire. The potent venom delivered by a bee sting, which can be deadly to even a large animal if enough doses are given, has evolved to protect the hive, Schmidt argued.

Most solitary wasps have stings far more mild than that of the honeybee. Schmidt said this is because wasps don't have as much to protect as bees; few predators are attracted to these insects' meager bodies or tasteless homes.

On the extreme end of the pain scale is the bullet ant, with a sting that can make anyone cry. This bug's incredibly painful sting likely evolved because the ant lives on the top of the rainforest canopy, unprotected, in plain view, where it would make an easy, tasty meal. The sting sends a powerful and memorable message to predators, Schmidt said.

"It's psychological warfare," Schmidt told Live Science. "Yes, there's pain and a little bit of damage. But mostly it's an intimidation game on their part more so than a heavy-artillery game. The bugs are the way they are because of how we react to them."

Schmidt's pain index grew largely out of his desire to educate himself about the venom pain range and to develop his explanation. He's no masochist — for most of the stings he recorded, Schmidt did not provoke the insect into stinging him. "The chicken that I am, I try not to get myself stung intentionally," he said.

But he has tested his pain theory by inciting some insects he predicted to be painless to sting him. And for the most part, he's been right about the mildness of their stings, he said.

The Schmidt pain index, which earned the researcher a 2015 Ig Nobel Prize (awarded to scientists for humorous-sounding research), ranges from 1 to 4, or from mild to excruciating. Schmidt placed the honeybee sting in the middle of the index, at 2.0, as a reference, because it's a sting many people have experienced.

Aside from equipping "Ant Man" with useful knowledge, what's the purpose of such a pain index in the real world, you might ask? Well, in a cruel application, you can use the index to mock anyone making a fuss about a sting from a puny, little fire ant (minor stuff, as far as stings go), but pity the poor soul stung by a bullet ant. This, Schmidt described as "pure, intense, brilliant pain, like walking over flaming charcoal with a 3-inch [7.6 centimeters] nail embedded in your heel." The fire ant sting is a 1; the bullet ant sting is a 4.

But Schmidt said he also sees practical uses for his index. A medical provider could use the chart to assess your response to a sting. If you were stung by a fire ant and it feels more painful than a honeybee sting, you may be having an adverse reaction to the sting. With more serious stings, medical providers could use the pain index to understand the nature and expected duration of the pain, in order to better treat you.

Schmidt is rather colorful and thorough in his sting descriptions, too. He described the 1-point pain of the mud dauber as "sharp with a flare of heat; jalapeno cheese when you were expecting Havarti." The Matabele ant has a sting at the 1.5-point level, comparable to a "child's arrow [that] misses its target and finds its home in your calf." [Image Gallery: Ants of the World]

A type of wasp called a velvet ant or cow killer produces pain that is at the 3-point level, "explosive and long lasting, [in which] you sound insane as you scream." And should you encounter the sting of the warrior wasp, at the 4-point level, that's simply "torture; you are chained in the flow of an active volcano [asking] why did I start this list?"

His pain, our gain.

Follow Christopher Wanjek @wanjek for daily tweets on health and science with a humorous edge. Wanjek is the author of "Food at Work" and "Bad Medicine." His column, Bad Medicine, appears regularly on Live Science.