Nicknamed "cow killers," you don't want to be stung by a velvet ant. Photo courtesy of Jillian Cowles/Johns Hopkins University Press

Pain is notoriously subjective.

Some people can take more of it than others. Yet we still need to measure pain, and so scientists have derived scales that are generally considered valid ways of assessing just how much one thing hurts compared to another.

When entomologist Justin Schmidt created the "Schmidt Pain Scale for Stinging Insects," he gave the world the first measure for comparing the pain of a yellowjacket sting ("Hot and smoky, almost irreverent. Imagine W.C. Fields extinguishing a cigar on your tongue") to that of a tarantula hawk wasp ("Blinding, fierce, shockingly electric. A running hair dryer has just been dropped into your bubble bath").

But as Schmidt mentions in his new delightful new book, "The Sting of the Wild," even his four point scale (a yellowjacket scoring a two, the tarantula hawk a full-on four) has limitations, as stings on different parts of the body hurt in different ways.

For example, Schmidt's base for the scale, a honey bee, generally rates a two: "Burning, corrosive, but you can handle it. A flaming match head lands on your arm and is quenched first with lye and then sulfuric acid."

But a honey bee sting on the back of the hand, he writes, is a very manageable 1.5. A sting on the tongue, on the other hand, is worth bumping up to a full three: "It's crawled into your soda can and stings you on the tongue. It's immediate, noisome, visceral, debilitating. For 10 minutes life is not worth living." So where do stings hurt the most?

Enter Michael Smith.

After reportedly suffering a bee sting on that most sensitive of male body regions, the testicles, Smith was struck with a curious question that — if this were not for science — would certainly cross the boundary into pure masochism.

Smith wanted to know where it hurt the most to be stung. He devised a plan to sting 25 different body parts, using guard bees from the same hive. He randomized the order of the stings so he'd let a bee sting each body part three times, for 60 seconds each time, enough to inject a full dose of venom. He received three experimental stings each day along with two daily "calibration" stings on the forearm.

He rated stings from one to ten (most painful), with a five being the middle ground. And since each body part was stung three times, he calculated the average.

Perhaps surprisingly — unless you've been stung in one of these spots — the nostril and upper lip beat out even those locations especially painful for men. (Smith is the only one who has conducted such an experiment, so we don't have data for women. Any volunteers?)

One particularly impressive and or cringe-inducing thing about Smith's experiment is that he actually intentionally stung himself each time — even Schmidt, creator of the notorious pain scale, received most of his stings incidentally while conducting other research.

Unfortunately, Smith didn't test the tongue, so we can't see how that compares to Schmidt's own experience. He also decided against stinging himself in the eye, since, as he wrote in the study where he published his results, his advisor feared he'd blind himself.

And yes, it's true that other individuals might perceive sting pain differently. A "four" for one person could be a "nine" for someone else. Even Smith's own pain ratings may have been affected by how much pain he expected to feel from each sting.

But as Schmidt writes in his book, "Michael's study took honey bee sting pain science to a new high."