Horsehair Worm (also known as Gordian Worm)
Scientific Name: Gordius aka Gordioidea (phylum Nematomorpha)
Order & Family: Order: Gordioidea, Phylum: Nematomorpha
Size: Typically 4 to 14 inches (10 to 35 cm) long, but extremely thin (1/25 to 1/16 inch diameter).
Natural Habitat
Adults are free-living in freshwater sources like puddles, troughs, streams, and wet soil. Larvae are internal parasites of terrestrial arthropods such as crickets, cockroaches, and beetles.
Diet & Feeding
Larvae absorb nutrients directly through their skin while living inside insect hosts. Adults generally do not feed, surviving on stored energy to reproduce.
Behavior Patterns
They are famous for their parasitic lifecycle where they manipulate the behavior of their host (e.g., a cricket) to seek out water, causing the host to drown so the adult worm can emerge. In the adult stage, they are often found tangled together in 'Gordian knots'.
Risks & Benefits
Risks: Harmless to humans, pets, and plants; they do not parasitize people. Benefits: They are beneficial as natural pest control because they parasitize and kill common nuisance insects like cockroaches, crickets, and grasshoppers.
Identified on: 2/14/2026