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Nobody knows how many insects live in the Congo Basin. Nobody has counted, and nobody is close to counting.
A look at the deadliest insects of the Congo Basin, from malaria-carrying mosquitoes and baboon spiders to tsetse flies, driver ants, and fleas.
Key Takeaways
- Insects cause far more human deaths in the Congo Basin than large predators like leopards or crocodiles.
- Disease vectors such as mosquitoes, tsetse flies, and blackflies remain major public health threats despite significant progress.
- Vector control measures like bed nets, fly traps, and mass drug treatment have dramatically reduced several deadly diseases.
- Dangerous animals are not always the most visibly threatening; the smallest creatures can have the largest impact.
What the video covers
- Insect-borne disease kills more than 700,000 people a year, with malaria alone accounting for over 600,000 deaths, mostly children under five.
- Baboon spiders live in dry ground like savannah and woodland, burrow with silk-lined tunnels, and bite without warning, though no confirmed human deaths from their bites exist.
- Tsetse flies carry trypanosomes that cause African sleeping sickness, a disease that progresses from fevers to brain involvement, and also kill up to 3 million cattle a year.
- African honeybees are far more aggressive than European bees, mobilizing hundreds of guards over greater distances and staying hostile for days.
- Honey badgers tolerate stings well but bees can still kill them, showing that even hardy animals are vulnerable to massed insect attacks.
- Onchocerciasis (river blindness) is spread by blackflies and caused by worms that live 10 to 15 years, requiring annual ivermectin treatment to control larvae.
- Driver ant colonies are built from millions of individual workers around a queen who lays millions of eggs per month, and their raids can overwhelm animals that cannot escape.
- Lymphatic filariasis, spread by mosquitoes, causes severe swelling of limbs and can be partially prevented by sleeping under bed nets.
- Tsetse-borne and other vector-borne diseases have declined greatly through screening, vector control, and treatment, though the flies themselves still cover vast areas.
- The video argues that insects, not the large predators most people fear, are the greatest threat to human life in the Congo Basin.
Chapters
- 00:00Introduction: The Hidden Insect Threat
- 01:48Baboon Spiders of the Congo
- 04:42Tsetse Flies and Sleeping Sickness
- 08:00African Honeybees and Honey Badgers
- 12:00River Blindness and Blackflies
- 15:00Driver Ants and Their Colonies
- 18:30Lymphatic Filariasis and Mosquito-Borne Disease
- 23:00Plague Fleas and Final Thoughts
Full Transcript — Download SRT & Markdown
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over 600,000 of them. And most of those are children under 5 years old. That's more than one death every minute.
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What we do know is what they do. Insect-borne disease kills more than 700,000 people every year. Malaria alone accounts for over 600,000 of them, and most of those are children under five years old. That's more than one death every minute.
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leopard, or the gaboon viper with the longest fangs of any snake alive. Add up everything they kill in this basin in a year, and it isn't a fraction of what the insects do. People here don't hang nets over their children at night
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By the time this video ends, another 24 will be gone.
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A baboon spider covers the palm of an adult hand. Females run 4 to 6 in across the legs. Males a little smaller. Up close, the last segments of the legs are thick and hooked, and that's what the name refers to. [music] They look like a
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And nowhere on Earth is that insect more at home than this forest. Ask anyone what to be afraid of in the Congo jungle, and they'll tell you the crocodile, the hippo, the leopard, or the Gaboon viper with the longest fangs of any snake alive. Add up everything they kill in this basin in a year, and it isn't a fraction of what the insects do.
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tunnel with silk, and sit just inside the entrance waiting for something to walk past. They eat insects mostly and small lizards when they can get them.
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People here don't hang nets over their children at night because of leopards. They hang them because of something a fraction of that size that they'll never see or hear coming.
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Most tarantulas give you a warning first. They rear up. They flick irritating hairs off the abdomen.
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A baboon spider covers the palm of an adult hand. Females run 4 to 6 inches across the legs. Males are a little smaller. Up close, the last segments of the legs are thick and hooked, and that's what the name refers to. They look like a baboon's fingers.
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They bite with no display at all. Which is why keepers who've handled tarantulas for 20 years won't put a hand near one.
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They don't live deep in the jungle. Baboon spiders favor dry ground they can dig in, like the savannah, woodland, and the drier country around the edges of the Congo Basin. They excavate their own burrows or move into abandoned ones, line the tunnel with silk, and sit just inside the entrance waiting for something to walk past. They eat insects mostly, and small lizards when they can get them.
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have a spider in the same category as [music] the wandering spiders of South America or the funnel webs of Australia.
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Nothing gets chased. Anything that walks too close to the entrance is pulled straight down into the burrow, and the spider feeds on it underground.
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world. People buy them deliberately, knowing exactly what they are. So, this is the animal almost everyone [music] pictures when they think about what's waiting in that forest. It's the largest animal in this video, and [music] it has the most painful bite of anything in it.
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Most tarantulas give you a warning first. They rear up. They flick irritating hairs off the abdomen. They make a performance of it. Biting is the last thing on the list. Baboon spiders skip all of that. They bite with no display at all, which is why keepers who've handled tarantulas for 20 years won't put a hand near one.
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Nothing about a tetsi fly looks dangerous. It's slightly bigger than a housefly, brown, gray, with wings folded flat over the back like a pair of scissors. And it has done more damage to Africa than any animal with teeth.
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And the bite is brutal. Severe pain, heavy swelling, and muscle spasms that can run on for days. What it doesn't do is kill you. There is no confirmed human death from a baboon spider bite anywhere. Africa doesn't have a spider in the same category as the wandering spiders of South America or the funnel-webs of Australia. The spiders on this continent that put people in hospital are southern African, and the most notorious of those lives in desert, not forest. That's why the most defensive tarantula in Africa is also one of the most widely kept in the world. People buy them deliberately, knowing exactly what they are.
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And while they're doing it, they can leave behind a single-sellled parasite called a trapanosome. What follows comes in two stages. First, the fevers, headaches, swollen lymph nodes, and joint pain. Then, the parasite crosses into the brain. And the second stage
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So this is the animal almost everyone pictures when they think about what's waiting in that forest. It's the largest animal in this video, and it has the most painful bite of anything in it.
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human African trapanosmiasis, but everyone else calls it [music] sleeping sickness because that's what it looks like from the outside.
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But the thing that actually empties villages out there is the size of a housefly.
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still reports 61% of them. A disease that once defined this region is nearly gone. The fly though never went anywhere. Tetsi still hold 9 million km across 37 countries. An area almost the size of the United States. The Congo
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Nothing about a tsetse fly looks dangerous. It's slightly bigger than a housefly, brown-gray, with wings folded flat over the back like a pair of scissors. And it has done more damage to Africa than any animal with teeth.
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Across Africa, the fly is estimated to kill up to 3 million cattle a year. So, the cattle weren't removed from the Tetsy Belt. They were never able to live in it. A herd driven into infested country sickens within weeks. And the
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Unlike mosquitoes, where only the females drink blood, both sexes of tsetse feed. They punch through skin with a rigid proboscis and take a full meal. And while they're doing it, they can leave behind a single-celled parasite called a trypanosome.
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and they produce a fraction as much. Where infection rates pass 30%, [music] keeping livestock and growing crops on the same land stops being possible. No plow animals, no manure for the fields, no milk. The disease is nearly beaten.
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What follows comes in two stages. First, the fevers, headaches, swollen lymph nodes, and joint pain. Then the parasite crosses into the brain. The second stage takes the thing your body is least able to do without: loss of coordination, behavior changes, and a sleep cycle that turns you nocturnal. Asleep through the day, awake all night, until the pattern breaks down altogether. Doctors call it human African trypanosomiasis, but everyone else calls it sleeping sickness, because that's what it looks like from the outside.
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An African honeybee sting is no worse than one you'd get in an English garden.
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Untreated, it's usually fatal. For most of the last century, it killed on a scale that emptied entire regions of the Congo Basin. Then screening, vehicle-mounted fly traps, and treatment beat it back. Fewer than a thousand cases a year are reported worldwide now, and the DRC still reports 61% of them. A disease that once defined this region is nearly gone.
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responding to something about 20 ft away. Disturb an African colony and several hundred come out to a disturbance 120 ft away. European bees calm down within an hour or two. African bees can stay hostile for days. A disturbed European colony will leave you
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The fly, though, never went anywhere. Tsetse still hold 9 million square kilometers across 37 countries, an area almost the size of the United States. The Congo Basin sits inside it.
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bad day carries enough venom to kill a healthy adult outright. [music] They also swarm 10 or more times a year, where a European colony manages one or two. More colonies in more places closer to [music] more people. And in the Congo
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The same parasite infects cattle, causing anemia, collapsing milk yields, and infertility, and then it kills them. Across Africa, the fly is estimated to kill up to 3 million cattle a year. So the cattle weren't removed from the tsetse belt. They were never able to live in it. A herd driven into infested country sickens within weeks, and the animals that die fastest are the ones worth the most. The big zebu breeds that give the most milk and pull the heaviest loads have no resistance at all. The only cattle that survive are small West African breeds with natural tolerance, and they produce a fraction as much.
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only people, either. Honey badgers are built for this. Quarterin hide, long claws, and a tolerance for [music] stings that would finish almost anything else. Bees still kill them. Badgers caught in traps at commercial apiaries have been stung to death on numerous
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Where infection rates pass 30%, keeping livestock and growing crops on the same land stops being possible. No plow animals, no manure for the fields, no milk. The disease is nearly beaten, but the poverty it created remains. One fly, and an area the size of the United States still farms without animals. It barely kills anyone anymore. It changed a continent anyway.
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68,000 people a year. One country. Malaria killed 610,000 [music] people worldwide last year. 95% of them in Africa and the Democratic Republic of the Congo alone accounts for nearly 12% of every African malaria death. Only Nigeria is worse at just under 32%.
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The next one has changed nothing at all.
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build eggs and she steals it from the mammal closest [music] to her. While the female feeds, she injects saliva to stop the blood clotting. And if she's carrying plasmodium falciperum, the deadliest of the malaria parasites, it goes in with the saliva. It reaches the
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An African honeybee sting is no worse than one you'd get in an English garden. Same venom, same dose. Nothing special about the chemistry at all.
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the [music] parasites generations are synchronized. In children, it goes further. Infected cells clog the small vessels of the brain. That's cerebral malaria and it means seizures, coma, and death. The reason this particular species is the most effective killer of
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What's different is how many come at once, how fast, and how long they stay infuriated. Disrupt a European bee colony and 10 to 20 guard bees come out, responding to something about 20 feet away. Disturb an African colony and several hundred come out to a disturbance 120 feet away. European bees calm down within an hour or two. African bees can stay hostile for days.
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the mosquito is tuned to exactly [music] that. So, the deadliest animal in this forest is a female mosquito, an eighth of an inch long, and she has killed more people in the Congo Basin than everything else in this video put
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A disturbed European colony will leave you with 10 or 20 stings at most. A disturbed African colony delivers between 100 and a thousand. People have died from as few as 100. The estimated average lethal dose for an adult is somewhere between 500 and 1,000 stings. So a single disturbed African colony on a bad day carries enough venom to kill a healthy adult outright.
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water, fast, broken, oxygen-rich rivers and streams. The exact water that makes a river basin worth living beside, which is why the villages closest to the best water get hit hardest and where the disease gets its name. The fly carries a
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They also swarm 10 or more times a year, where a European colony manages one or two. More colonies, in more places, closer to more people. And in the Congo Basin, people go looking for them. Wild honey is worth climbing for, and the people who collect it do it with smoke and bare hands, up a tree, with nothing between them and a colony that could turn on them at any moment.
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through the skin, and when they die, the immune system reacts to the corpses, [music] not the worms, resulting in constant inflammation. The itching [music] is bad enough that people can't sleep through it. When the larae reach the eye, the
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It isn't only people, either. Honey badgers are built for this: thick hide, long claws, and a tolerance for stings that would finish almost anything else. Bees still kill them. Badgers caught in traps at commercial apiaries have been stung to death on numerous occasions.
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that works called ivamectin, but it kills the larae, not the adults. And an adult worm lives 10 to 15 years. So treatment isn't a course. It's an annual dose every year for a decade and a half until the worms inside you die of old
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No single bee can kill a person. That takes a colony. The next one does it on its own.
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it's mostly harmless. The problem is what happens when you give ivormectin to someone carrying a heavy load of it. The dying worms can trigger catastrophic inflammation in the brain. Deaths have been documented, including in the Democratic Republic of the Congo, which
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Malaria killed 610,000 people worldwide last year, 95% of them in Africa. The Democratic Republic of the Congo alone accounts for nearly 12% of every African malaria death. Only Nigeria is worse, at just under 32%. Three-quarters of the people malaria kills in Africa are children under five.
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blindness. One worm blinds people. The other makes the cure for it lethal, and they live in the same jungle.
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Only female mosquitoes bite. Unlike the tsetse, where both sexes drink blood, a male mosquito lives on plant sugars and never touches it. The female needs protein to build eggs, and she takes it from the mammal closest to her. While she feeds, she injects saliva to stop the blood from clotting. And if she's carrying Plasmodium falciparum, the deadliest of the malaria parasites, it goes in with the saliva. It reaches the liver first and multiplies there, q
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no difference whatsoever to how efficiently they work. A single colony holds between 1 million and over 20 million ants. Weigh them all together and you get 20 to 30 lb of ants, a mass roughly equivalent to a midsized dog
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made entirely of individual animals a few millime. Underneath it is one queen, and she is the most productive animal in this forest. A driver ant queen lays 3 to 4 million eggs per month. Across her life, a quarter of a billion. She mates 15 to
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20 times when she's young and stores the sperm, up to 880 million of them, and then never mates again. Everything that column does for the rest of her life comes out of that one fortnite. When they hunt, they don't send scouts.
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Hundreds of thousands of workers move forward as a single front across the ground and up into the low vegetation and they take whatever is in it.
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Insects larae worms eggs nestlings carrying, anything slower than the front and the column is followed. In the Congo basin, birds shadow driver ant raids to catch whatever breaks cover ahead of them. an entire feeding strategy built around walking in front of an ant swarm.
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Chimpanzees do something even stranger. They cut sticks, strip them, push them down into the nest, wait for the ants to swarm up the stick, then pull it out and eat them off it. It's one of the clearest examples of tool use in any
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wild animal. So, here's what 20 million blind ants with cutting jaws have actually done to people.
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There is no verified human death from a driver ant swarm. The claim you'll find everywhere that they'll attack anything, including human beings, describes what they're capable of, not anything that has happened. And the reason the story survives [music] is that the capability
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is real. A driver ant column will overwhelm and strip an animal that cannot get away from it. Something tethered, [music] something caged, something already injured. A person can walk away. That's the difference. The last one in this forest doesn't need you
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to stay still. It waits until you're asleep. In parts of the Congo Basin, something comes out of the floor at night and drinks blood from people while they sleep. It's a maggot. the lava of an ordinaryl looking fly about 3/4 of an
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inch long when it's fully grown and it's named after the Congo basin. It lives in the dust and [music] the cracks of earth floors. After dark, it comes out, finds bare skin, and feeds for around 20 minutes. Then it lets go, drops off, and
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goes back into the floor until the next night. It does not burrow into you. It doesn't lay eggs in the skin or tunnel under it. It feeds from the outside like a leech and it leaves. Its actual hosts
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are burrow dwellers, wthogs, arvarks, and hyenas. Animals that sleep in the same earth hollow [music] night after night, so the larae always know where to find them. A person who sleeps on the same earth floor every night is no
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different from a wartthog in a hole. The fly never adapted to us. We moved into the place it already hunted, which is why there are records of it appearing in Congo basin communities as they stopped moving through the forest and settled in
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one place. And what does it do to you? Nothing. It takes a small amount of blood. It carries no disease at all. Not malaria, not sleeping sickness, nothing. There is no illness associated with it anywhere in the medical literature. It's
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prevented entirely by sleeping on a bed. The worst sounding animal in this entire forest is stopped by furniture.
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Houses across the Congo Basin have a spider living on their walls inside and out. The gray wall jumping spider is one of the most peculiar spiders on Earth.
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It's about 9 mm long and it clears several times its own length in one single jump. It does it without any muscle. Spiders don't carry the leg muscle to launch themselves. Instead, they extend their legs hydraulically, forcing body fluid into them under
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pressure until the leg straightens. A grasshopper folds up and loads its legs before it goes. A spider has nothing to coil, so there's nothing to give the jump away. And before every jump, the greywall jumping spider glues a thread
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of silk to the wall behind it. Not a web, this spider builds no web and sets no trap at all. It's a safety rope. It breaks against that line, steadies itself with it midair, and climbs back up it when the jump misses.
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To aim a jump like that, it needs exceptional vision. And it has eight eyes with the front two doing the work.
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built more like a telescope than anything an insect carries. For an animal this size, the resolution is extraordinary. What it gives up is width. Each of those eyes sees sharply through a slit 2 to 5° across. The retinas inside its head swing
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independently behind the lenses, sweeping that narrow strip across the wall until something crosses it. On the paler species, you can watch it happening through the carropus.
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Indoors, what it hunts is mainly house flies. It'll take prey twice its own size, like crane flies, and they've also been seen going after stingless bees.
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It's the only one that moved in with us. Everything else in this documentary is still in that forest.
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This spider moved onto the walls of human buildings, and the buildings carried it off the continent. It's established now in Florida, Texas, California, the Caribbean, and many parts of South America. A Congo basin animal on four continents. And it got
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there by sitting still on a wall. That's the only animal here that wants nothing from us. However, the next one spends 6 to 8 years inside you before you notice it.
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A single mosquito bite is enough to give you malaria. The other thing mosquitoes carry in this forest takes repeated bites over years before it takes hold.
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And it doesn't kill anybody. It's a worm. The females run 3 to 4 in long and under a third of a millime thick. And they don't settle under the skin or in the eye. They move into the lymph system, the network of vessels
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that drains fluid out of your tissue and puts it back into the blood. The adults take up residence inside one of those vessels and stay there for 6 to 8 years.
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Their larae do something precise. They stay out of the bloodstream during the day and come into it at night in the hours the mosquitoes are flying.
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A blood sample taken from an infected person in the afternoon can come back clean.
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And most people carrying it never show a thing. No swelling, no pain, nothing anybody would take to a clinic. And they're infectious the whole time.
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In two villages in the Congo, researchers tested 820 people. Just under a third were carrying the parasite. One in eight had its larae circulating inside them. In the ones who do develop it, the damage isn't done by the worm directly. The adults block and
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stretch the vessel they're living in until the drainage stops working and fluid that should be leaving the tissue stays in it. The limb swells, the skin thickens and hardens, and it doesn't go back down.
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In men, it collects in the scrotum instead. 25 million men worldwide have that. Over 15 million people have the swollen limbs and 657 million people across 39 countries are still living where it's transmitted.
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There's a drug and it doesn't fix any of it. It instead clears the parasite out of the blood and stops you from infecting anyone else, but it does nothing for the limb. By the time the disease is visible, the drainage is
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already gone and it doesn't grow back. Which is why the care for the late stage isn't medicine. It's proper washing and hygiene. The hardened skin cracks, the cracks get infected, every infection wrecks a few more vessels, and the
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swelling goes up another step and stays at the new size. Keeping it clean is what delays the next step.
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Most of these people were infected as infants. The worms that did it are long gone. The leg carries on getting worse.
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That worm needs decades to ruin a leg. The next one needs about 3 days to kill you.
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Contrary to popular belief, the plague never went away. Most of the cases reported to the World Health Organization between 2019 and 2025 came from two countries and one of them is the Democratic Republic of the Congo.
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The bacterium lives in the rodents of the Congo Basin and the flea is what moves it between them. When the rodents start dying, the fleas go looking for the next warm animal and a lot of the time that's a person.
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What happens inside the flea is the part worth understanding. The bacteria multiply in its gut and build a mass across the valve at the front of it.
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They start within an hour of the infected meal. By the next day, around 7 in 10 fleas have one. Over the following 2 weeks, it hardens until blood can't get past it.
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So, the flea is starving with a full stomach. It can't pump a meal down, so it bites over and over, far more often than a healthy flea ever would. Every attempt scrapes bacteria off that mass and pushes them into the wound. The
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blockage that's killing the flea is the thing that makes it dangerous. In a person, it takes 1 to 7 days. The bacteria collect in the nearest lymph node, and it swells into a hard lump called a boubo. untreated, that kills 30
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to 60% of the people who get it. If it gets into the lungs, two things change. The window drops to as little as 24 hours, and the flea stops being necessary at all because from there, it moves between people on the breath.
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Untreated, the lung form kills between 30 and 100% of them. In 2020, one health zone in Ituri province recorded 45 cases and nine deaths in 5 weeks. Across the whole province that year, 64 cases and 14 deaths against 10 cases and five deaths
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over the same stretch of the year before. It's treatable. Antibiotics work and they work well as long as they're started in the first day or two. The first day or two is also how long the whole thing takes. 10 animals.
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The one with the worst bite has never killed a human. 20 million workers and cutting jaws has never killed anybody.
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The one named after this place drinks blood out of sleeping children and carries no disease at all. And the one that has killed more people in this forest than every other animal in it put together is an eighth of an inch long.
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and you would swat it without pausing the conversation you were having. 24. Since this started, none of these animals hunt people. They aren't predators. They want a few drops of blood. And almost all the damage is done by something they're carrying
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rather than by them. And between them, they have decided which half of Africa can keep cattle. Which villages have to be abandoned by the best water? How many children in the Congo basin see their fifth year on Earth?
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Nothing in the Congo that looks dangerous is. And nothing that's killing people out there looks like anything at all. Thank you for watching this video.
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Which animal do you want us to take apart next? Put it in the comments. A species, a river, a place? We read them all. We've also just launched a second channel covering the oceans and the [music] animals in them. Be sure to
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subscribe.
Topics:Congo Basindeadliest insectsmalariasleeping sicknesstsetse flybaboon spiderdriver antsAfrican honeybeesriver blindnessinsect-borne disease
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