The World s Deadliest Bug ISN T From Australia

You're looking at the most dangerous bug in the entire world. Where most assassin bugs hunt insect prey, these guys have graduated to a much more challenging target. You. And it's not even their bite that makes them dangerous. So it's living in this insect's gut that actually kills you. Hope you've got a strong stomach, because we're diving deep into the world of bloodthirsty parasites. As darkness falls, a flat, skittering insect ventures out from between cracks in its rocky hideaway. This habitat is crawling with deadly creatures, but it isn't the outback of Australia or in the middle of Arizona's Sonoran Desert. And this weird-looking bug is responsible for more human kills than most of the venomous snakes here. Now, there are few insects that are this unsettling to me. And you'll already see that I'm using forceps instead of my own hands to hold onto it. Because this is probably the nastiest bug you could ever possibly come across. What I have right here is a kissing bug, and its name may sound somewhat pleasant. Like, oh, it's gonna give you a nice little kiss. But don't be fooled. This is probably the most dangerous bug in the entire world. Responsible for tens of thousands of deaths a year, this is not just one of the deadliest insects, but one of the deadliest animals on the planet. You know it's a big deal when I'm not hands-on with a creature. Normally, I'm out braving arid deserts and tropical rainforests to handle some of Earth's deadliest invertebrates. I often do get hands-on with animals to show their true nature. Simple creatures just trying to make their way in the universe. But this isn't a video where I'm going to mythbust or otherwise disprove that the kissing bug is dangerous. I'm not holding it in my bare hand for a reason. And it has nothing to do with this insect's bite. Now, this is an assassin bug. And I see comments all the time when I'm working with assassin bugs saying, oh, they're deadly. They spread Chagas disease. The truth is, it's only this particular insect that is dangerous to people. And there are assassin bugs in the subfamily Triatominae. And the best way to tell you're looking at a kissing bug is actually look at the head there. See that really, really pointed nose and that thin, creepy-looking rostrum there? These guys have another name, the blood-sucking cone noses. And they get that because of that really cone-shaped skinny head. Most assassin bugs don't have that cone head. They have kind of a blunt beak that comes down to a sharp point. Their head isn't quite as long as this. So that's one of the best ways to tell looking at a dangerous kissing bug. You'll also notice that it actually has some aposematic warning coloration on the back. That jet black color with the red accents usually is a warning that something is dangerously venomous. But I actually wonder if, in the case of the kissing bug, if it's actually mimicry. Because their bite is not known to be very painful. It doesn't seem to be their venom that actually kills you. What's happening is something even more insidious and even more terrifying. It isn't the bite of the kissing bug that makes it so terrifying. The bite is only part of the kissing bug's deadly secret. But to understand why, we first need to dig into what makes this bug different from all the rest in the first place. We throw the word bug around a lot to kind of describe any weird little invertebrates that might turn up in our backyards. Anything from worms to slugs to spiders to insects. But technically the word bug really only describes one group of insects. The order Hemiptera. The order Hemiptera is a vast group of insects. And there's so much diversity within the true bugs, it's hard to even describe a simple way to identify them all. Except for one feature. The bigger clade that all insects belong to is called Mandibulata. And it's a group of arthropods that have mandibles instead of chelicerae. That's kind of how arthropods are divided. You have spiders and arachnids and stuff in the chelicerata and insects, crustaceans, and myriapods in the mandibulata. But the mandibles of the Hemipterans have been modified. They've fused into straw-like mouthparts they use to basically suck out the insides of whatever they're eating. Whether it's plants, other animals, or even you, Hemipterans are sucking, not chewing. It's one of my favorite groups too because they kind of really get creative with it. You have just about every body plan, every role in the ecosystem you could possibly think of. Everything from cicadas that spend over a decade underground before emerging for just one summer, to camouflaged ambush predators, to insane moth-like herbivores. The Hemipterans get wild. And within the Hemiptera, there's one family that has particular interest for today's topic. And that is the Reduvidae, the assassin bugs. These are among the largest terrestrial true bugs in the world, with wheelbugs and horrid king assassin bugs reaching up to multiple inches in length. They get their name because they are assassins. They're lying in ambush, usually waiting for other insects to come to them, then pouncing on them and piercing them with that beaked rostrum right in the front. They have these sharp, piercing mouthparts, and these insects are armed with a paralyzing venom that kills their prey in seconds and dissolves their insides so they can slurp it up just like a milkshake. The bite of an assassin bug is usually immensely painful, one of the most painful experiences you can receive from an insect. But what's crazy is, as painful as their bite is, most of them are really not that scary. They're not aggressive, and their bite might leave you with a welt, but there's no permanent symptoms associated with any of these insects. Except for the triatominae, a weird subset of assassin bugs that split off somewhere around 100 million years ago. We're not sure why one group of assassin bugs decided to become parasites, but somewhere along their lineage, insect prey might have been scarce. And because kissing bugs tend to be more associated with rock crevices and caves, it's possible that the only other animals near them were things like bats and rodents. And since assassin bugs need to feed on the body fluids of other animals, they had to make do with the other animals that were around. You've probably been bitten by mosquitoes before. I mean, anyone who's gone outside ever has been bitten by mosquitoes at some point, one of the drawbacks of touching grass. But have you ever wondered how these biting insects even find you in the first place? Insects that feed on mammal blood are what we call hematophagous. And when your entire diet revolves around blood, you need a good way of detecting your warm-blooded victims. They rely on a few different cues to find their prey. At long distance, they hone in on rhythmic pulses of carbon dioxide. As we breathe, we release this gas into the air. These six-legged vampires have evolved special receptors to smell the CO2 we breathe and hone in until they can detect other cues that were there. As they get closer, our body heat shows up on their radar. We actually release infrared light. It's outside of our range of vision, but the insects that feed on us can detect it from significant distances away. Once they've got our carbon dioxide and heat signature, it's only a matter of time before they lock onto our scent and come in for the bite. In the caves these kissing bugs call home in their natural habitat, there are lots of rodents and bats that use the rocky structure as shelter, which means a buffet for these reclusive arthropods. And they come out in the dead of night, hungry for blood. They actually get the name the Mexican bed bug because in different parts of Mexico and Latin America, they're found in people's bedrooms. They hide inside the mattress or inside cracks and crevices in your bedroom, coming out only in the dead of night to feed. They're following heat signatures, smelling bursts of CO2 as you exhale in the night, and that gives them clues that a meal is ready. But these guys are greedy feeders, so they literally will poop to make room for the next blood meal. It's this poop that we need to fear. At this point, we've talked about how dangerous the but in a way, the actual bug is just a nuisance that causes an itchy bite. On its own, the kissing bug is completely harmless, and there are even some species that are not typically considered deadly to people. It's what lives inside the poop that's dangerous. What makes this creature so dangerous isn't its venom. It's what lives inside it. See, this is actually more than one organism. Living in the gut of this creature is a microscopic protozoan, a life form from its own kingdom. It isn't an animal. It isn't a bacteria. It isn't a plant or fungus. It's a whole different thing, and it lives inside this insect. What happens is when these creatures are feeding, they actually will poop to make room for their next meal, and inside their gut lives a parasite by the name of trypanosoma cruzii. That parasite comes out in the poop, and then it gets even more disturbing. Trypanosoma cruzii is the pathogen behind the deadly Chagas disease. In acute cases, it will kill you. In most cases, it just causes life-altering symptoms. Named for Carlos Chagas, the Brazilian physician who first studied and described the disease, Chagas disease is a nightmare. It occurs in two stages, acute and chronic. The acute stage, when the parasite is first getting established, might have a swollen welt near the bite site. Sometimes fever and malaise will show up, but the scariest part is many cases go completely asymptomatic. It's the chronic stage where this disease gets truly frightening. Unless you're treated with an antiparasitic, you will remain infected after the acute phase ends. This isn't some run-of-the-mill cold or flu. The disease attacks your organs, most commonly your heart and digestive system, leading to heart disease in up to half of all chronic cases. When it kills you, it's because your heart can no longer pump blood through your body, leading to cardiac arrest. Chagas disease claims nearly 10,000 human lives every single year, meaning the kissing bug is among the deadliest animals on the planet. I talk a lot about deadly creatures here on the channel, but what actually are the deadliest animals in the world? They might surprise you. Spiders aren't on the list, sharks are barely on the list, and they're not even in the top 10. Counting down from 10, you have crocodiles with around a thousand kills a year, tapeworms with 2,000 kills per year roughly, roundworms with about 2,500 kills per year, freshwater snails with around 10,000 deaths per year, kissing bugs, finally, with around 10,000 kills per year as well, tsetse flies with around 10,000 kills per year, dogs with over 25,000 kills per year, snakes with around 50,000 kills per year, people with over 475,000 kills per year, and finally, mosquitoes with nearly three quarters of a million human deaths per year. What's crazy is in the top 10, only one of them is there because of venom. Venom is by and large nowhere near the most deadly thing that animals are using against us. In fact, all of the insects that are up there, the mosquitoes, the tsetse flies, and the assassin bugs, it's not even the insects themselves that are killing us. It's diseases that these insects spread, and the kissing bug is tied for fifth deadliest animal in the world with the freshwater snails and tsetse flies. Yeah, this thing, this thing kills more people than any spider ever has, and it's only killing less people than snakes because in parts of rural Asia and South America, access to medical treatment isn't that great. As far as deadly animals in the western hemisphere are concerned, the kissing bug is really, really high up there. But what's crazy is they didn't originate around humans. They used to stick to caves and rock crevices and stuff, so how exactly is it that they're killing so many people? The answer is we've moved into their habitat. And the thing is, these are nocturnal animals, but they actually have pretty good vision. You notice compared to other assassin bugs, they have rather large compound eyes. They're using that probably to detect infrared light in the darkness of night to help them hunt their mammalian prey, but that means they're also drawn to other lights, like your porch lights. Yeah, even here in my home state of North Carolina, I have seen dead kissing bugs in the spider webs at my porch lights in the summer. They are a real threat throughout most of the southern part of this country. Makes you think twice about having your lights on at night, doesn't it? What's basically happening is they zoom in towards that porch light, and then once they get to your house, they find little cracks and crevices to hide during the day. Little gaps in your door or your window. They worm their way into your bedroom, and at night, there's no bright lights, but there's infrared light emanating off of your body. Heat. They follow that heat to its source, and then, rhythmic release of carbon dioxide as you just breathe in your sleep, confirm to the kissing bug that it is a living, breathing animal that it's been attracted to. They're rather large insects, but they are extremely light-footed and very sneaky with how they move. They crawl up over your shoulder, looking for thin skin to just ever so imperceptibly bite. The reason they get the name kissing bug is they often will bite the corner of your lip right here. Areas where the skin is really thin and really vascular, and they will fill themselves up with your blood before disappearing back down a crack. What happens is these guys are typically feeding near mucosal membranes. Things like your mouth, your eyes, areas where the skin is soft, and there's lots of capillaries and stuff that can feed off of. The thing is, when it bites there, it might not be painful, but it is very itchy. When you wake up in the morning, you have this itchy bite on your eye, on your mouth. You go, and you kind of rub it. You're like, oh, what the heck happened? Do you think you have a cold sore or maybe a zit or something that happened in the night? As you're rubbing, that liquid poop gets rubbed into the bite. As disgusting enough as it is, that is where your fate is sealed. That trypanosoma, that parasite, gets into the womb, gets into your bloodstream, and then wreaks havoc on your physiology. There's a lot of mystery around the parasite trypanosoma cruzi. We're not sure exactly what the first animal it infected was. In fact, we're not even sure how its life cycle evolved. This organism is not an animal. It's not a fungus. It's its own thing. It's an acclade called discoba, one of the groups that were formerly called protists, and it's a type of organism called a euglenoid, which are named after euglena, a sort of algae-protozoan hybrid kind of thing that moves around with a flagellum, the single whip-like tail. That's kind of how this thing moves, but instead of living in pond water, it's living inside larger organisms. But the way that this organism survives, it's why it's so dangerous to people. Trypanosoma can only live inside of other animals, and it spends most of its life inside mammals. Like I said, we're not sure what mammal it started in, probably bats or rodents, and it spreads when the kissing bug feeds on an infected animal. It lives inside your cells. The type of protozoan that it is basically burrows into the cell membrane in your tissues, in your organs, and then it just decides to replicate inside your cells. Kind of like a virus, over time it just bursts your cells open and then spreads, infecting more cells, in more cells, until it's used up all the cells in your body. Where this infection gets particularly dangerous is when the parasite inevitably makes it to your heart. Because they seem to travel mostly through your blood, well, your blood eventually gets to your heart, and when they infect that tissue, you start to have serious cardiac problems. And given that we kind of need our heart to survive, and we need our heart to be operating as good as possible to live a healthy and long life, you can start to see why Trypanosoma cruzii is so deadly to humans. Chagas disease is one of the nastiest illnesses you can get, and it literally claims tens of thousands of lives throughout the western hemisphere every single year. Here in the U.S., Chagas is quite rare. We're at the southern border of the U.S., and this is where these guys start to get more common. But as you work your way south, into Mexico, into Latin America, these become more and more prevalent, and the incidence of these guys actually carrying the parasite gets higher. In many of my videos, I try to paint scary animals like snakes, spiders, and centipedes in a more positive light to show how we don't need to fear creatures that might be dangerous. This is not going to be the case with the kissing bug. Unlike spiders and snakes, they actively hunt us and should be considered highly dangerous. What's funny though is this is exactly one of the reasons to keep spiders and other creepy crawly arthropods around. They may look scary, but they don't want much to do with us. They do, however, love to eat the bugs that find their way into our homes. In parts of the southwestern U.S., some people don't mind when certain species of huntsman spider find their way into the house, partially because they eat the highly venomous Arizona bark scorpions, but also because they clean up the kissing bugs that find their way in too. Throughout the kissing bugs range in the U.S., there are various large spiders that would happily hide away in forgotten corners of your house where you don't even need to see them, and they can also help keep you safe from these potentially deadly insects. Personally, I'd rather have the creepy spiders than the parasite-carrying assassin bug. But that is one terrifying insect. It doesn't look like much, but honestly, it's the stuff like this that doesn't look that impressive, doesn't look that scary, that sometimes hides the most terrifying secrets. The most insane part is that the deadly nature of the kissing bug is an unintended byproduct of their evolution and lifestyle. They don't mean to be deadly. They're just trying to get by and survive. It's insects like these that make me happy to have spiders and scorpions around. Venomous or not, they're a lot less terrifying than the parasite this thing carries. It's kind of neat when you think about it. The best solution to combat these deadly bugs is another arthropod. Whether it's feeding on other bugs or leveling up to take on animals as large as us, arthropods have found their way into just about every role in the ecosystem. Decomposers? Check. Herbivores? Check. Predators? Check. And even parasites. They've diversified well over the nearly 500 million years they've existed on our planet, but not all of them have changed as much as these have. Some arthropods are living fossils. Their build has served them so well over the millennia that there's been little pressure for them to look or act different than they did in prehistoric times. One of the most ancient of these is not only one of the largest arthropods on the planet, it's also the largest arachnid. What if I told you that the world's biggest arachnid wasn't a tarantula and didn't even live on land for most of its life? Despite its name, the horseshoe crab is not a crab at all. It's a giant marine arachnid, and in the latest episode of Beyond the Backyard, I'm heading to the Jersey Shore to get face to face with these alien creatures during one of their rare appearances on land. I have always loved the weirdest lifeforms in our world, and it doesn't get much weirder than horseshoe crabs. My new series, Beyond the Backyard, dives into the secret lives of bizarre creatures just like these. In every episode, I head beyond my backyard on adventures into some of the most remote, or in this case, unique, habitats on Earth to find equally unique animals and tell their stories to the world. From the far reaches of Australian outback to the mountain rainforests of Central America, our world is full of amazing biological secrets just waiting to be discovered. And we're going beyond the backyard to find them all. You can watch this show today only on Nebula. Nebula is home to the most thoughtful videos on the internet. From deep dives into engineering secrets to the mysteries of our own bodies, it's got a rabbit hole for just about everything you might find yourself wanting to know more about. Founded by independent creators for independent creators, you know that every video you watch has real love put into it, and you can feel it in every frame. Not relying on sensational algorithms, this allows me to cover some more obscure and lesser known animals that would otherwise be totally forgotten here on YouTube, oftentimes animals that you've been requesting for ages. 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