Horsehair worm

Scientific Name: Nematomorpha

Order & Family: Order: Gordioidea; Family: Various (e.g., Gordiidae)

Size: Typically 4 inches to 14 inches (10 to 35 cm) long, but very thin (1 to 3 mm).

Horsehair worm

Natural Habitat

Freshwater environments such as ponds, streams, troughs, and puddles; also found inside terrestrial insect hosts.

Diet & Feeding

Larvae are internal parasites of insects (crickets, grasshoppers, beetles); adults do not eat and function only for reproduction.

Behavior Patterns

Adults are free-living and form knotted masses (Gordian knots) during mating. They manipulate their host's behavior to seek water, where the adult worm emerges.

Risks & Benefits

Harmless to humans, pets, and plants. They are beneficial for the ecosystem as they help control populations of insects like crickets and grasshoppers.

Identified on: 3/12/2026