Horsehair worm is a long, thin worm that looks like a coiled hair from the mane or tail of a horse. It is sometimes called a hair snake or hairworm. There are hundreds of species (kinds) of horsehair worms. Most of them live in the shallow water of lakes, ponds, and streams. They may grow as long as 3 feet (91 centimeters), but most are shorter. The majority of horsehair worms are black or brown.
Female horsehair worms lay thousands of eggs. A larva hatched from an egg forms a small, round structure called a cyst. The cyst may be eaten by a beetle, cricket, or grasshopper. The larva may then emerge from the cyst and penetrate beyond the insect’s intestine. The young worm lives there as a parasite. The larva may also use a special organ to bore its way into the body of an insect. After the worm reaches maturity, it leaves the insect and lives freely in the water.
