'Horsehair' or 'Gordian' worms are found in many streams and look much like plain thick pieces of horse hair (hence their name) around 10 cm long. Juvenile worms live as parasites inside insects of the order 'Orthoptera' (grasshoppers, crickets etc.) being ingested as eggs laid on vegetation on the banks of streams. Here they feed on the internal organs of their insect host and grow larger. When fully grown the insect host is 'encouraged' to return to the water by the parasite, presumably through production of hormones by the worm. When the water's edge is reached they burst from the insect's body, killing it, and then entering the water to become a non-feeding adult.

Conservation status: There is very little known of the ecology of these bizarre animals, however they are unlikely to be threatened.