Unless you live in the Marvel universe, a horror movie, or a sci-fi show, you probably assume mind control is nothing but fiction meant to terrify us. After all, what could be more horrifying that taking away free will, then doing something you would never do because someone else made you, and there was nothing you could do to stop it. Thankfully, mind control isn’t real, right?
Except that it is. And among insects, it’s quite common. Here are four of the most terrifying parasites in the lowest orders of the animal kingdom.
One of the most well-known of the parasitic Kilgraves of the animal kingdom is the zombie-ant fungus. As the name suggests, it’s a fungus that controls ants’ minds and turns them into zombies. Ants encounter the spore, where it incubates inside them for several days. Then, the fungus takes over the ant’s brain and has them crawl up the side of a tree 25 centimeters off the ground, clamp into a leaf, and then stay there until it dies. The next day, a stalk grows out of the ant and explodes spores onto the rainforest floor, where the whole cycle can start over.
Emerald Cockroach Wasp
With a glittering emerald body and two crimson legs, the emerald cockroach wasp is a handsome insect with a beautiful name and a terrifying personality. The wasp first stings the roach, thereby paralyzing it, and then injects the roach with a stream of neurotransmitters that renders the insect a zombie. The wasp then drinks some of the host insect’s blood, clasps onto its antennae and leads it back to the nest, where it lays its eggs inside the roach’s body. The cockroach stays inside a corral of sorts, which it could escape, but controlled by the wasp, it does not. Eventually, the wasp larva eats the roach alive, and then from the roach’s dead carcass to start the cycle again.
Kamikaze Horsehair Worm
These look like a harmless piece of spaghetti at first. And, as long as you’re not a grasshopper or cricket, they are. A fly or mosquito carries the larva to the grasshopper, which consumes it. The larva develops inside the host insect until it is ready to complete the cycle. The worm must be underwater to do this, however, and grasshoppers do not go near the water. But the worm, which can control the grasshopper’s central nervous system like a puppeteer handling a puppet, forces the grasshopper to dive into the water. The host drowns, and the worm can reproduce.
The most famous mind-control parasite is probably Toxoplasma gondii, which affects humans and many other mammals. T. gondii works by making the host reckless, encouraging them to make decisions that make them easy prey. In rats, for instance, T. gondii turns fear into attraction, making the rats run straight up to their feline predators.
The broodsac, T. gondii’s more flamboyant cousin, works similarly. This flatworm infects a snail, whose appearance changes. The snail’s eye stalks pulsate with emerald- and olive-green stripes flecked with charcoal and topped with a bright maroon. As far as birds are concerned, the snail now looks like a caterpillar with a flashing neon sign over its head. The worm also controls the snail’s behavior, making it sit out in the open where the birds can even quickly snap up their conspicuous snack. The worm then reproduces in the bird’s stomach, and the cycle repeats itself.
Perhaps most terrifying is, in all of the above cases, there are no outward symptoms until it is too late. Sometimes, the parasite just remains dormant until the perfect moment. Parasites, like viruses and bacteria, often mutate, and quickly. Most may be limited to insects, but you never know — one could be controlling your brain at this very second.