These Hairworms Eat a Cricket Alive and Control Its Mind

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A baby hairworm hitches a ride inside a cricket, feasting on its fat until the coiled-up parasite is ready to burst out. Then it hijacks the cricket’s mind and compels it to head to water for a gruesome little swim.

If you’re out on a hike and look down at a puddle, you might spot a long, brown spaghetti-shaped creature whipping around madly in a figure 8.

It’s a hairworm – also known as a horsehair worm or Gordian worm – and researchers have described 350 species around the world. Good news: It isn’t interested in infecting or attacking humans. But if you had happened on the puddle a few hours earlier, you might have witnessed a gruesome spectacle – the hairworm wriggling out of a cricket’s body, pushing its way out like the baby monster in the movie “Alien.”

How a hairworm ends up in a puddle, or another water source such as a stream, hot tub or a pet’s water dish, is a complex story. A young hairworm finds its way into a cricket or similar insect like a beetle or grasshopper, and once it’s grown into an adult, the parasite takes over its host’s brain to hitch a ride to the water.

As a result of the infection, crickets stop growing and reproducing. Male crickets infected by hairworms even lose their chirp, said Ben Hanelt, a biologist at the University of New Mexico who studies hairworms.

What is a hair worm?
A hair worm or hairworm – pick your spelling – is a nematomorph. Nematomorpha are a group of parasites. They’re long, thin worms that can grow to be several meters long inside their host.

Can humans be infected by a hairworm?
There are reports of humans and cats and dogs being infected by hair worms, but hair worms aren’t after us or our pets because they can’t grow inside us, said Hanelt. They can only grow inside a host like a cricket or a related insect.

Hi, my name is Rachel. I am the chief editor's better half. I am a part-time pharmacist, full time mum of three kids. I love running, going to the gym and crafts.