The hairworm might not look like much, but it is a sinister parasite that steals its host’s genetic code to manipulate it into deep water, so it can reproduce and start the cycle all over again.

During its larval stage, a hairworm’s first goal is to get eaten by a tadpole or a mosquito. It then lies dormant until this initial host is itself eaten by a larger creature, such as a cricket, grasshopper, or mantis. Once its Trojan horse is digested by the new host, the hairworm breaks out and begins sapping the poor insect of nutrients. This only takes about three months, after which the hairworm somehow manipulates its drained host toward water, where it would never go on its own, to drown. Hairworms breed in water, so after their host dies, they swim to the nearest ball hairworms to reproduce and start the cycle once more. Scientists have known about the worm’s ‘mindsnatcher’ trick for years, but a team of researchers claims to have finally figured out how hairworms actually brainwash their hosts.

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Capitojoppa amazonica is a newly-discovered genus of parasitic wasps that stabs its victims with its giant ovipositor and sucks the blood out of them before laying its eggs inside.

The terrifying insect was discovered by scientists from the University of Utah while surveying the National Reserve of Allpahuayo-Mishana in Peru. They laid large netted devices called malaise traps to capture as many flying insects as possible. Among the creatures caught in their traps was a bright yellow wasp with a giant almond-shaped head and tube-like organs sticking out of it. Scientists concluded that the specimen, an adult female, was a new ‘solitary endoparasitoid’ – meaning it lays a single egg inside the body of its host (caterpillars, beetles, and even spiders). The egg hatches in a matter of days, after which the wasp larvae start to consume the host’s inside.

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23-year-old Nichola Kratka, a self-described ‘extreme eater’, deliberately ate a fish infested with tapeworms and filmed himself doing it in the hopes of going viral on TikTok.

It’s shocking what some people will do for a bit of online attention these days. Take this young Florida content creator who, after catching a tapeworm-infested bass while fishing on a lake. Instead of throwing away the fish after discovering the parasites, he decided to eat it, knowing full well that he could become infected. Unsurprisingly, it wasn’t long until he started experiencing side effects like stomach aches, diarrhea, nausea, siziness, and weakness. In the end, he had to seek medical help and start taking deworming medication. Still, Kratka said he had “no regrets”…

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Sacculina carcini is a common species of barnacle that not only attaches itself to various species of crab, forcefully castrating males and turning them into females willing to care for and release their eggs.

Most barnacles spend their entire existence attaching themselves to underwater rocks or the bottoms of ships and just filtering food from water, but sacculina carcini has evolved into a parasite that seeks out unsuspecting crabs, usually green crabs, and becomes the bane of their existence. It all starts with a microscopic Sacculina larva that attaches itself to the most vulnerable part of the crab, the membrane at the base of one of its hairs, and injects a microscopic blob called ‘vermigon’ into the crustacean’s bloodstream. This blob then grows into a parasitic barnacle that uses its host both for protection and reproduction, often changing its sex to achieve its insidious goal.

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Cymothoa exigua, popularly known as the tongue-eating louse, is a parasitic isopod that attaches itself to the tongue of its fish host, severs circulation, causing the organ to necrose and fall off, and then becomes the new tongue.

We’ve covered a bunch of terrifying parasites on Oddity Central, but few can hold a candle to the tongue-eating louse in terms of creepiness. This critter is one of the few that actually does the phrase “what nightmares are made of” justice. It enters fish through the gills, attaching to them until it matures, at which point it changes sex from male to female. Once this process is complete, the parasite starts to make its way to the fish’s mouth, where it attaches itself to its tongue using its incredibly powerful legs. It then pierces the host’s tongue with its strong bite and begins to suck the blood out of it. The blood vessels can’t keep up with their appetite, and the tongue eventually withers and detaches from the fish.

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The pen you’re about to see is one of those shocking products that makes people say they’ve seen it all. This Japanese souvenir actually comes with a live nematode parasite swimming inside it…

Anisakis is a genus of parasitic nematodes that infect various species of fish and can cause anisakiasis  – a parasitic infection of the gastrointestinal tract – in humans who consume raw or undercooked seafood containing larvae of the aforementioned nematode. Some people can also suffer an acute allergic reaction like anaphylaxis after eating fish infected with anisakis. In short, this aquatic parasite is not the kind of thing you’d want anywhere near you, so why would anyone create a pen with a live anisakis worm encased inside?

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Thyrinteina leucocerae, the caterpillar of the geometer moth, is targeted as a host for a species of parasitoid wasp that can lay up to 80 eggs inside its body. The caterpillar’s reward is a job as bodyguard for the very parasites growing inside it and a slow, agonizing death.

The Glyptapanteles wasp is one of nature’s most fascinating and, at the same time, terrifying body-snatchers. Not only does its lay dozens of eggs into caterpillar hosts, but scientists claim that the insect can somehow change the behavior of the host, turning into a mindless bodyguard whose only mission is to protect the wasp’s eggs against predators. Once the wasp grubs hatch out of its body and begin to spin their pupae, the caterpillar stops moving, stops eating, gets on its hind legs and goes into statue mode. But at the slightest threat for the wasp “babies”, it starts swinging its head violently to drive predators away.

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A 59-year-old Chinese man who had experienced frequent headaches and even seizures over the last 30 years is now able to lead a pain-free life after doctors extracted a 10-cm worm from his brain.

The man, surnamed Zhang, first started experiencing excruciating headaches and seizures in 1989. He was playing cards with friends when his arms and legs started twitching for no reason. He started foaming at the mouth and lost consciousness soon after. His worried family took him to a hospital in Guangzhou where he was diagnosed with epilepsy and prescribed anti-epileptic drugs. Despite taking the drugs regularly over the last 30 years, he still suffered occasional seizures and fainting, as well as frequent headaches. It wasn’t until last month that Zhang learned that his symptoms were actually caused by a worm stuck in his brain.

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The Amazon rainforest is home to many frightening creatures, like giant Anacondas, flesh-eating piranhas, just to name a couple, and now you can add a new one to the list, a species of wasp that lays its eggs on the abdomen of spiders and then hijacks their brain, essentially turning them into zombies.

The previously unknown wasp of the Zatypota genus was discovered by researchers with the University of British Columbia (UBC) working in the Ecuadorian Amazon basin. They documented its symbiotic relationship with a species of so called “social spiders” and recently published some truly terrifying findings in the Ecological Entomology scientific journal. This newly discovered wasp is apparently able to hijack the nervous system of its host, forcing it to leave its colony, which it otherwise rarely does, protect the wasps larva and ultimately get eaten alive. It essentially turns the social spider into a zombie-like drone that then does the wasp’s bidding.

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As if habitat loss and pesticide exposure weren’t enough to deal with for bumble bees, they also face increasing pressure from a parasitic fly that attacks them midair, injects them with eggs with hatch larvae which proceed to eat the pollinators from the inside before finally forcing them to dig their own graves.

It sounds like something out of a body snatchers horror movie, but the conopid fly is very much a real-life threat for bumble bee colonies already under a lot of pressure from human activities. The conopid fly is classified as a parasitoid, a parasite that not only feeds on its host, but ends up killing it in a gruesome, terrifying way. We’ve featured creepy body snatchers in the past, some that turn their host into zombies, others that simply take control of their bodies but leave their brains intact, but the conopid fly is even worse. It literally eats bumble bees from the inside, before somehow forcing them to land on the ground and dig a whole to die in. The injected parasite grows inside the host and ultimately bursts out of it as a mature conopid fly that attacks other bumble bees and continues this nightmarish cycle.

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Doctors in Russia recently reported the unusual case of a woman who noticed that a number blemishes appeared to move around her face every few days. Those blemishes turned out to be a live parasitic worm crawling under her skin.

The unnamed woman first noticed a small bump under her left eye, but didn’t pay too much attention to it until, five days later, when it disappeared only to be replaced by three larger blemishes above the eye. Then, 10 days later, those disappeared as well, but her upper lip became swollen. Disturbed by these symptoms, the Moscow-based woman sought medical help and ultimately learned that those strange bumps were actually a live parasitic worm called Dirofilaria repens slithering under her skin.

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Human zombies might be a figment of the imagination, but ‘zombie bees’ actually exist. They are ‘created’ when regular honeybees get infested with a particular type of parasite. The bees begin to display highly erratic and bizarre behavior that’s very zombie-like. These infested bees were first discovered in 2008 in California by John Hafernik, a professor of biology at San Francisco State University.

Ever since the initial discovery, zombie bee-sightings have been reported in Oregon, Washington State, California and South Dakota. According to Professor Hafernik, “They fly around in a disoriented way, get attracted to light, and then fall down and wander around in a way that’s sort of reminiscent of zombies in the movies. Sometimes we’ve taken to calling it, when they leave their hives, ‘the flight of the living dead.’”

The culprit here is the Apocephalus borealis, a parasitic fly that is known to implant its eggs in ants. The fly larvae live off the ants’ brains, dissolve their connective tissues and eventually finish off the ants. Researchers now have reason to believe that the flies have found a new home for their eggs – European honeybees that are common in the United States. The flies lay their eggs in the bees that eventually hatch, wreaking havoc in their hosts’ bodies.

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