Amazingly, the entire horsehair worm grew and developed as a parasite inside the body cavity of crickets and other large insects such as grasshoppers, katydids, beetles and cockroaches. This internal parasite of insects does not harm humans, animals or plants. Parasitized crickets are thirsty and go to water to drink. While there the horsehair worm emerges from the insect's body and swims away in the water, an essential step in the life cycle of this internal parasite. Insects infected with horsehair worms die as a result of the parasite.
Horsehair worms are white when they first emerge from the host's body.
Another name for horsehair worm is Gordian worm. Horsehair worms resemble hairs from horses actively moving in the water. A superstition once surrounding this species held that the worms in water troughs and puddles had miraculously come to life from the long, thin hairs of a horse's mane or tail that had fallen into the water. Horsehair worms are completely harmless. They do not infest people, livestock, pets or plants.