Horsehair worm
Scientific Name: Gordius sp. (and other genera in the phylum Gordiacea)
Order & Family: Order Gordioidea, family Gordiidae (within phylum Nematomorpha)
Size: Typically 10 to 35 cm (4 to 14 inches) long, but can reach up to 1 meter; very thin, usually 1 to 3 mm in diameter.
Natural Habitat
Found in aquatic or damp environments such as streams, ponds, puddles, and cattle troughs, as well as emerging from terrestrial hosts.
Diet & Feeding
Larvae are internal parasites of insects and crustaceans; adults do not eat as they lack functional digestive systems.
Behavior Patterns
Larvae develop inside an insect host (like a cricket or beetle). Once mature, they manipulate the host's behavior to seek water, where the adult worm emerges to mate and lay eggs.
Risks & Benefits
Generally harmless to humans, pets, and plants. They are beneficial to the ecosystem as they help control populations of insects like crickets and grasshoppers.
Identified on: 2/22/2026