That Worm That Makes Grasshoppers Go For A Swim
Category: The Animal Kingdom 9th July 2026
Look, you think you've seen pest behaviour. Then nature politely shows you a proper puppet show. There is a group of slender parasites called Nematomorpha, often called horsehair or gordian worms, and they specialise in turning ordinary insects into drunks with a death wish.
These things are mostly aquatic as adults. They mate and lay eggs in water. The larvae need to get into a living insect to grow, so they hitch a ride through a messy life of boozy biology-tiny critters, snails, whatever-until they end up inside a cricket, grasshopper, mantis or cockroach.
Once cosy inside, the worm gets on with growing. Then, when it's time, it does the daftest thing: it somehow convinces the host to head for water and jump in. The insect walks or flies straight into a pond, puddle or ditch. The worm wiggles out through a hole in the body or a polite escape hatch and slips into the water to carry on its life. The host often doesn't make it. Bit rude, really.
How it does this? Scientists have found the worm secretes molecules that mess with the host's nervous system. The exact trick is still not fully nailed down, but think chemical persuasion rather than subtle whispering. It's biology's version of leaving a weird note on your mate's sofa: 'Go swim.'
They're surprisingly long. A one-inch cricket can output a worm that, when it emerges, is sometimes many times longer than the poor bug that carried it-proper spaghetti. I've seen vids where a stunned grasshopper is left on the shore and a metre-long worm wriggles away like it owns the riverbank. I mean, you can't make that up.
It's one of those facts that makes you stare at a pond and wonder what the wildlife is really up to. Next time your garden cricket takes a suspicious stroll to the birdbath, don't blame the weather. There's probably a slimy conductor backstage, and it's quietly smug about its life choices.