Horsehair Worm

Scientific Name: Nematomorpha (Phylum)

Order & Family: Order: Gordioidea; Family: Various (often Gordiidae)

Size: Typically 10 to 70 cm (4 to 28 inches) in length, but extremely thin (1-3 mm diameter).

Horsehair Worm

Natural Habitat

Adults are free-living in freshwater environments like puddles, streams, troughs, and swimming pools. Larvae are parasitic inside insects like crickets and grasshoppers.

Diet & Feeding

Adults do not feed; they rely on stored energy. Larvae absorb nutrients directly from their insect hosts.

Behavior Patterns

Known for their 'zombie-like' manipulation of hosts, forcing them to seek water so the adult worm can emerge to reproduce. They are often found knotted together in masses (Gordian knots).

Risks & Benefits

Harmless to humans, pets, and plants. They are beneficial for pest control as they kill harmful insects like crickets, cockroaches, and grasshoppers.

Identified on: 2/18/2026