Horsehair Worm (or Gordian Worm)

Scientific Name: Nematomorpha

Order & Family: Phylum: Nematomorpha (Class: Gordioidea)

Size: Typically 10-70 cm long, but very thin (1-3 mm wide)

Horsehair Worm (or Gordian Worm)

Natural Habitat

Adults live in freshwater or damp soil; larvae are parasitic within insects or crustaceans.

Diet & Feeding

Adults do not eat (they lack a functional mouth or gut). Larvae absorb nutrients from their host's body fluids.

Behavior Patterns

Known for 'mind-controlling' their insect hosts (like crickets or grasshoppers) to jump into water so the adult worm can emerge to mate. They are often seen writhing in tangled knots, hence the name 'Gordian'.

Risks & Benefits

Harmless to humans, pets, and plants. They serve as a natural pest control by parasitizing and killing insects like crickets, grasshoppers, and cockroaches.

Identified on: 2/14/2026