Gordius is a genus of freshwater worms belonging to the family Gordiidae, commonly known as horsehair worms. These long, thin worms can grow several inches in length and are often found in ponds and streams. They are known for their unique life cycle, which includes a parasitic stage in insects before they emerge as free-living adults. The larvae of Gordius typically infect hosts like grasshoppers or crickets, manipulating their behavior to seek water. Once in a suitable environment, the worms emerge from their hosts, completing their life cycle. Gordius plays a role in the ecosystem by influencing insect populations and serving as a food source for various predators.