If you spend your life studying insects of the order hymenoptera, which includes wasps, bees and ants, you're going to get stung a few times. Justin Schmidt, entomologist at the University of Arizona, never intentionally set out to get stung by as many different species as possible, but entomologist fieldwork involves bagging live nests for study. When you dig an ant nest out of the ground or climb a tree to bag a wasp nest, the hymenopterans inside are generally pissed off. They sting.

Insects jabbed their stingers into Schmidt hundreds of times over the course of his career. In the mid-1980s, he decided to categorize these experiences scientifically. The result is a "pain index" that reads almost like a wine tasting guide.


He wasn't doing it just to be clever. The chemical events that allow such tiny weapons to inflict such outlandish pain is an area of fascinating research, and quantifying the pain generated by different insects helped organize that research. By 1990, Schmidt had revised the Schmidt Sting Pain Index to cover 78 species, ranking the pain intensity of their stings from zero to four.

At the low end of the scale, you'll find species like pharaoh ants and the Costa Rican wasp Polybia diguetana. At the scale's upper limit are the tarantula hawk wasp (top photo) and bullet ants. If you're thinking to yourself, "That's ok, most bugs will just leave you alone if you don't bother them," Schmidt also noted that the more painful the sting, the more aggressive the species tends to be.


Entomologist Christopher Starr at the University of the West Indies created a similar ranking system around the same time that Schmidt first created his. However, Starr's index wasn't quite as colorful as Schmidt's. For example, of the bald-faced hornet, Schmidt wrote, "Rich, hearty, slightly crunchy. Similar to getting your hand mashed in a revolving door." That's a two on the index. Yellowjackets also rank in at a 2.0, but notice the different quality of the pain: "Hot and smoky, almost irreverent. Imagine W. C. Fields extinguishing a cigar on your tongue."

What's really amazing is how stings are able to cause such pain. In a 2003 interview with Discover magazine, Schmidt likened wasps and their relatives to hackers manipulating cellular mechanisms. They do it all with a tiny amount of venom per insect. While each sting differs in the exact formulation, the chemicals injected perform a series of actions designed to generate pain despite a lack of long-term physical damage.


First, enzymes soften, then burst open cellular membranes. Some of these cells, inevitably, will be nerve cells. Wrecking these cells screws up all the electrochemical signaling that nerve cells do, so they end up firing off signals more or less at random (this explains not just the pain but also the spasms and shaking that some stings cause). Other chemicals restrict blood flow, keeping the pain-causing stuff undiluted and in one place. At the same time, new chemicals are released that allow the attack to move on to new cellular targets. Worst of all are the pheromones that enrage other wasps and let them know you're public enemy number one. Get stung once and more are on the way.

So what do those stings at the top of the list feel like? The tarantula hawk is so named because it's a huge wasp that attacks tarantulas. They're the stuff of nightmares, with huge stingers. The pain index describes them as, "Blinding, fierce, shockingly electric. A running hair drier has been dropped into your bubble bath."


Nothing really compares to the South American bullet ant, though. Their name offers a clue as to why they're ranked as the most painful insect sting in the world. They aren't shaped like bullets — getting stung feels as bad as getting shot. The official Schmidt Pain Index description says, "Pure, intense, brilliant pain. Like fire-walking over flaming charcoal with a 3-inch rusty nail in your heel." Schmidt had a personal encounter with bullet ants – he tried getting drunk to dull the pain, but even after 12 hours he was enduring spasms of agony.

Why did he get stung by bullet ants? He was digging out a nest and got a stung a few times. Sat down to "savor the experience," then dug some more. And got stung some more.


Now that is a man devoted to his job. And with an unusual taste for pain.


Conniff, Richard. "Stung." Discover Magazine, June 2003.

Starr, Christopher. "A Simple Pain Scale for Field Comparison of Hymenopteran Stings." Journal of Entomological Science, Vol. 20, No. 2 1985.


"Interview with Dr. Justin O. Schmidt." Zooillogix.

Photos: jonboy mitchell, Gilles Gonthier, EOL Learning and Education Group, graftedno1.