♪Intro♪ Now, I’m not a huge fan of pain, but it
IS super important, biologically speaking. It’s how your body tells your brain something
is wrong—that you’ve put your hand on a hot stove or broken your leg. It’s such a strong signal that lots of animals
have evolved to hijack it, and one group is especially notorious for that: the insects
in the order Hymenoptera: ants, bees and wasps. Many of them are armed with venom that causes
intense agony, and studying the compounds in those venoms can teach us a lot about how
pain works. But to study their venom, you have to brave
the bugs. Which is where entomologists like Justin Schmidt
come in. Since 1984, he’s catalogued the stings he’s
received — from over 80 different species — on a pain scale he calls the Schmidt Pain
Index. It goes from 1 to 4, with 1 being mildly annoying
and 4 being agonizing torture. Of course, his ratings are just one person’s
experience. But they line up with what we know from research
into these insects’ venoms, as well as what other people say about their stings. And they’re probably as close as we’re
gonna get to a scientific comparison of the pain. So, here are some of the worst stingers Schmidt
has encountered, and the biochemistry behind why they’re so awful. Welcome to SciShow List Show: Agony Edition. The term “fire ant” can refer to a few
members of the genus Solenopsis. But most of the time, people in the US are
talking about the red imported fire ant—Solenopsis invicta. Native to Central and South America, red imported
fire ants have invaded around the world. They’re incredibly aggressive as a species,
and have potent stings that help them win battles with native ants. They’re also known to kill baby bunnies
and hatchling sea turtles and other adorable small animals. In terms of pain, individual fire ant stings
are pretty mild. Schmidt only rates them a 1, and describes
them as “Sharp, sudden, mildly alarming. Like walking across a shag carpet and reaching
for the light switch.” But you’re rarely stung by a single fire
ant. Just ask anyone who’s accidentally sat on
one of their nest mounds, or made the mistake of touching a floating raft. That’s right, I said raft! These ants survive floods by linking their
waxy bodies together around their queen. The rafts can contain 100,000 living, squirming
ants looking for the first solid thing they can find. If that solid thing is your leg — or your
butt — you can be stung by hundreds of ants in a matter of seconds. More than 90% of their venom is made up of
alkaloids, which are organic, or carbon-containing compounds, that also have nitrogen in them. The specific toxins in fire ant venom are
chemically similar to piperidine, the compound that makes pepper peppery. And there’s a good reason people don’t
generally inject essence of pepper into their bodies: it triggers the release of immune
signaling molecules, causing burning, itching pain and a fluid-filled pustule. And while each individual sting might be a
“1,” the combined pain of hundreds is anything but “mildly alarming.” Then there’s the beloved honey bee, Apis
mellifera. Everyone’s favorite pollinator. And probably the sting most people have felt
for themselves, because they’re found basically everywhere. While they don’t have the most painful stings
on the planet, they can be deadly. In fact, in Europe, North America, and even
Australia, bees are deadlier than just about any other venomous animals. That’s because in those places, allergic
reactions to bee stings claim far more lives than snakes, scorpions, and spiders combined. And the sting ruins the bee’s day, too. Their stingers are covered in small barbs,
so when the bee tries to leave, the stinger and attached venom gland tissue stay behind. This kills the bee. According to Schmidt, the pain from a bee
sting is only a 2. He says it’s “Burning, corrosive, but
you can handle it.” I guess, assuming you’re not allergic to
it. The burning sensation comes from melittin,
which is a peptide — basically a small protein— that makes up 40-60% of the venom by weight. Melittin turns on the same pain receptors
as heat, so from the perspective of our neurons, it literally burns. In that way, it’s similar to capsaicin,
which gives hot peppers their heat. Both will cause intense pain and inflammation
when injected under the skin. We know, because scientists have done this
to people who for some reason volunteered to be injected. For science. There are lots of different wasps people call
“yellow jackets,” usually in the genus Vespula, and they’re all social, predatory
wasps. Like bees, they’re some of the most common
insects people get stung by all over the world, which is why they made this list. Also like bees, yellow jackets also get a
mere 2 from Schmidt. He describes it as “Hot and smoky, almost
irreverent.” Which, I don’t know what yellow jackets
he’s been stung by, but maybe they should get a room. Unlike bees, though, yellow jacket stingers
are smooth, which means they can sting over and over and over again. By weight, more than 90% of their venom is
made up of amines, a type of organic compound related to ammonia. Specifically, it’ll often contain histamine,
the same stuff that’s released when you have an allergic reaction, and serotonin,
which is a neurotransmitter involved in things like regulating your mood. Both compounds are used by your immune cells
to trigger inflammation, and receptors for them are important parts of your body’s
pain system. So it makes sense that injecting them into
your skin and muscles would hurt. The amount of histamine or serotonin in the
venom depends on the species. Eastern yellow jacket venom is 99.4% histamine,
while German yellowjacket venom is 98% serotonin. Both hurt like the dickens, but are weaksauce
compared to the rest of the stings on this list. Harvester ants get their name from their habit
of dragging seeds underground, which they store in large caverns called granaries. They’re native to the southwestern US, and
if you’ve never seen one that’s probably for the best: their stings earn a 3 from Schmidt. He calls them “Bold and unrelenting,”
like “Somebody is using a power drill to excavate your ingrown toenail.” We don’t have a whole lot of information
on how their venom works, but Schmidt thinks the most likely pain-inducer is a small peptide
in their venom called barbatolysin. Barbatolysin acts a lot like melittin in the
body, but it’s much more effective at killing cells, which might explain why stings from
these ants hurt more than bee stings. Harvester ant venoms are also surprisingly
lethal — for the species with the most potent venom, just 0.12 milligrams per kilogram of
body weight is enough to kill 50% of the animals injected with it. Drop for drop, that’s comparable to deadly
snakes like cobras. In theory, less than 10 milligrams of the
stuff would probably kill the average person. Luckily for us, these ants are pretty small,
so they only inject tiny amounts of venom at a time — at most about 25 micrograms,
or thousandths of a milligram. So it would take several hundred stings to
even come close to a potentially-lethal dose. The red-headed paper wasp is found in Central
and South America. As its name suggests, it’s got a red head,
and it’s a paper wasp, meaning it makes papery nests by mixing plant materials with
saliva to create a sort of paper maché. Schmidt gave its sting a 3, which he described
as “Immediate, irrationally intense, and unrelenting.” There isn’t enough research on this species
to know exactly what its venom contains, but all other members of its genus that have been
studied are armed with pain-inducing molecules called kinins. So the red-headed paper wasp probably has
them too. Kinins are a type of peptide, and like a lot
of the other compounds in the venoms on this list, they’re among the many molecules involved
in inflammation. They cause pain by turning on pain-sensing
nerves, and because they act on neurons directly, they’re called neurotoxins. In solitary wasps, kinins are used to paralyze
prey. But social wasps usually don’t capture their
meals with their stingers—they use their powerful jaws instead. They reserve stinging for defensive battles,
especially against mammals like us. Per drop, most of their venoms are pretty
weak. People only die when they’re swarmed by
dozens of them, or if they’re allergic. But these wasps don’t need deadly venoms. A jolt of pain is enough to get a predator
to back off, which can actually be more effective in some ways. Death doesn't let you learn. And what their venom lacks in brute lethality
they make up for in pain production. The more painful the venom, the more effective
the lesson to the would-be attacker—stay away, or you’ll regret it. It’s a strategy perfected by the next insect
on our list. Warrior wasps, sometimes called drumming wasps,
are also native to the Americas, and also live in big colonies. As their name implies, they have an aggressive
reputation, and an especially eerie way of warning you of what’s to come if you get
too close to their nest. When warrior wasps feel threatened, hundreds
of them will rhythmically scrape their nest in unison, creating a loud, drumming sound. At the same time, they’ll flap their wings
to the beat, adding a seriously creepy visual display to the noise. Part of the reason for this ostentatious warning
is that, like honey bees, their stingers are barbed—so they stand to lose a chunk of
their abdomen if they sting. So it’s much better for them if you listen
to the drumming and keep your distance. And it’s really not a concert you want to
be at. Warrior wasp stings are excruciating. Schmidt gives them wasps his highest pain
rating, a 4. In his words, the stings are “Torture. You are chained in the flow of an active volcano.” The pain he experienced was so awful that
for the first time, he even questioned his decision to start his list. But what’s even more striking than the level-4
agony is how long the pain lasts. Warrior wasp stings burn for over two hours. So whatever causes such unrelenting pain,
it must be pretty stable and hard for our bodies to break down. Schmidt thinks it’s probably a kinin, just
like the slightly less painful paper wasps, but we don’t know much about exactly what’s
in it. Apparently researchers aren’t too enthusiastic
about analyzing some of the most painful venom in the world. Can’t imagine why. When you hear “tarantula hawk,” you might
picture a giant spider. Or maybe a bird that eats spiders. But tarantula hawks are neither of those things. They’re wasps in the genus Pepsis, found
in the Americas. They get their name because they’re gigantic
— they can be 5 centimeters long, big enough that they can seem more like a bird than an
insect. And they feed their babies tarantulas. They have a whole bunch of adaptations that
help them go after such dangerous meals. Their legs are long and gangly, allowing them
to grapple even large, wriggling tarantulas. And, of course, they produce a lot of venom
that they use to subdue their prey. Their stings cause Schmidt level 4 agony. “Blinding, fierce, shockingly electric. A running hair drier has been dropped into
your bubble bath.” That’s mostly because of the unusually high
amount of acetylcholine in their venom. Acetylcholine is something you use a lot in
your nervous system, mainly to send signals between neurons and to other cells. It’s basically the go-to neurotransmitter,
and it triggers both your motor and pain neurons. So not only does the sting hurt: it also makes
any muscles nearby clench hard, which is both painful and paralyzing. That’s the point — tarantula hawks use
their venom to paralyze their prey, because tarantulas generally don’t like being eaten
and would otherwise fight back. Thankfully, at least for us humans, the effects
of these stings don’t last long—mere minutes. That’s because your body is already well-equipped
to clean up acetylcholine. Whenever a neuron releases the stuff, you
have to remove any excess floating around after the signal is received as quickly as
possible. If you didn’t, you’d just keep triggering
neurons over and over again. So you have the enzyme acetylcholinesterase,
which chops it up. That means we can rid ourselves of tarantula
hawk venom pretty quickly. The spiders can too, eventually. But by the time they regain control, they’ve
already lost the battle, and become a meal for the wasps’ young. Last and definitely not least, we have the
bullet ant. You might think the name for these Central
and South American ants comes from the fact that they’re 2 or 3 centimeters long, so
maybe about the size of a bullet. You’d be wrong, though. They’re called bullet ants because being
stung by one is supposedly just as painful as being shot. Obviously, Schmidt ranks them a 4—in some
versions of his index, a 4+. He describes their stings as “Pure, intense,
brilliant pain. Like fire-walking over flaming charcoal with
a 3-inch rusty nail grinding into your heel.” Along with the pain, the stings often come
with fever, sweating, trembling, and local paralysis. And that agony lasts forever. Or at least it feels like forever. Venezuelans call them hormiga veinticuatro,
or “24 ant,” in honor of the 24 hours the pain sticks around for. That’s because the main pain-inducer in
the venom, called poneratoxin, is an impressively powerful neurotoxin. Poneratoxin directly stimulates neurons by
opening the sodium channels they use to send electrical signals. And it doesn’t just do this once. It does it over, and over, and over, and over,
and over. So there you have it: eight agonizing stingers,
and what we’ve learned from the scientists who willingly line up to study them. There’s still a lot we don’t know about
venom, but we can learn a lot about how our bodies work at the molecular level by understanding
how the compounds in them produce pain. By studying them, researchers hope gain a
better understanding of chronic pain, and maybe even find new ways to treat it. Thanks for watching this SciShow List Show,
brought to you by our patrons on Patreon. If you want to help support this show, just
go to patreon.com/scishow. We promise being a patron won’t hurt one
bit. ♪Outro♪
