Horsehair worms prey upon cockroaches, crickets and other bugs, like this poor mantis above. As larvae, they’re typically ingested by the host. They then mooch off nutrients while hiding in the circulatory system. But it’s their arrival into adulthood that’s made them a gruesome viral star. They fatally erupt from the insect, their full length often several times longer than the host, reaching over 1 foot. Some species also manipulate the insect to first dive headlong into a body of water, drowning it and creating a comfy trip to the marine environment where the worm naturally dwells.
