Horsehair Worm (also known as Gordian Worm)
Scientific Name: Gordius robustus (and other species within the Phylum Nematomorpha)
Order & Family: Order: Gordioidea, Family: Gordiidae (Taxonomy varies, generally Phylum Nematomorpha)
Size: Typically 10 to 35 cm (4 to 14 inches) in length, but extremely thin (about 1-3 mm in diameter).
Natural Habitat
Adults are free-living in freshwater environments like puddles, troughs, streams, and swimming pools. Larvae are parasitic inside arthropods like crickets and grasshoppers.
Diet & Feeding
Adults generally do not feed; they live on stored energy. Larvae are parasitic and absorb nutrients directly from the insides of their insect hosts.
Behavior Patterns
Known for their life cycle where they develop inside terrestrial insects (like crickets) and then manipulate the host's behavior to seek water, where the adult worm bursts out to reproduce. They often twist themselves into intricate knots, hence the name 'Gordian'.
Risks & Benefits
Generally harmless to humans, pets, and plants. They cannot infect mammals. They are considered beneficial in some contexts as they act as a biological control for pest insects like crickets, grasshoppers, and cockroaches.
Identified on: 2/16/2026