Horsehair Worm

Scientific Name: Gordius robustus (and other species in Phylum Nematomorpha)

Order & Family: Order Gordioidea, Families include Gordiidae and Chordodidae

Size: 10 to 75 centimeters (4 to 30 inches) in length, but only 1 to 3 millimeters wide

Freshwater environments like streams, ponds, and puddles; found globally

Larvae are parasites of insects (crickets, grasshoppers, beetles); adults do not eat and focus only on reproduction

They exhibit a parasitic life cycle where they manipulate their host's behavior to make it enter water, where the adult worm then emerges to mate

They are harmless to humans, pets, and plants; they provide ecosystem benefits by naturally controlling certain insect populations

Identified on: 12/26/2025