Horsehair Worm (Gordian Worm)

Scientific Name: Nematomorpha (Phylum)

Order & Family: Order: Gordioidea, Families vary (e.g., Gordiidae, Chordodidae)

Size: Typically 10 to 100+ centimeters (4 to 40 inches) in length, but extremely thin (1-3 millimeters wide).

Horsehair Worm (Gordian Worm)

Natural Habitat

Adults live in freshwater environments like puddles, streams, and livestock troughs. Larvae are parasitic within terrestrial insects like crickets, grasshoppers, and beetles.

Diet & Feeding

Adults do not feed; they rely on energy stores. Larvae are parasitic and absorb nutrients directly from the insides of their insect hosts.

Behavior Patterns

Larvae infect insect hosts (like crickets) and manipulate the host's behavior to seek water. Once the host enters water, the adult worm bursts out to reproduce. The adults are often seen writhing in tangled knots, hence the name 'Gordian'.

Risks & Benefits

Harmless to humans, pets, and plants. They cannot infect mammals. They are considered beneficial as they help control populations of pest insects like roaches, crickets, and grasshoppers.

Identified on: 2/26/2026