Horsehair worm
Scientific Name: Gordius robustus (and related species in Chordodes)
Order & Family: Order Gordioidea, family Gordiidae
Size: Generally 4 inches to 14 inches (10 to 35 cm) long, but very thin (about 1 to 3 mm in diameter).
Natural Habitat
Freshwater environments like streams, ponds, and puddles; also found in moist soil or emerging from host insects near water.
Diet & Feeding
Larvae are internal parasites of insects (crickets, grasshoppers, beetles); adults do not eat and function only for reproduction.
Behavior Patterns
They exhibit 'mind control' over their host, forcing the insect to seek out water. Once the host reaches water, the adult worm emerges through the host's body wall to mate and lay eggs.
Risks & Benefits
They are harmless to humans, livestock, and pets. They benefit the ecosystem by naturally controlling populations of crickets, grasshoppers, and cockroaches.
Identified on: 2/17/2026