Horsehair Worm (also Gordian Worm)

Scientific Name: Nematomorpha (Phylum), Gordius spp. (Common Genus)

Order & Family: Order: Gordioidea, Family: Gordiidae

Size: Typically extremely long and thin; 4 to 14 inches (10-35 cm) in length, but only about 1-3 mm in diameter.

Horsehair Worm (also Gordian Worm)

Natural Habitat

Adults are found in freshwater sources like puddles, streams, troughs, and cisterns; larvae are internal parasites of arthropods like crickets and grasshoppers.

Diet & Feeding

Adults generally do not feed, relying on stored energy. Larvae are parasitic, absorbing nutrients from the internal bodies of host insects (crickets, grasshoppers, beetles).

Behavior Patterns

Known for their 'Gordian knot' mating balls where many intertwine. The larvae manipulate host behavior, forcing the terrestrial host to jump into water so the adult worm can emerge.

Risks & Benefits

Harmless to humans, pets, and plants. They are beneficial as biological controls for pest insects like grasshoppers, crickets, and cockroaches.

Identified on: 2/16/2026