Horsehair Worm (Gordian Worm)

Adults are aquatic, found in puddles, swimming pools, troughs, streams, and ponds. Larvae are parasitic inside terrestrial arthropods like crickets and grasshoppers.

Adults do not eat (they rely on stored energy). Larvae are parasitic and feed on the internal tissues and fluids of their insect hosts.

They are famous for their parasitic lifecycle where larvae manipulate host behavior, driving insects to drown themselves in water so the adult worm can emerge. Adults often ball up into tangled knots.

Harmless to humans, pets, and plants. They cannot bite, sting, or infect mammals. They are considered beneficial biocontrol agents for pests like crickets, cockroaches, and grasshoppers.