Horsehair worm
Scientific Name: Gordius robustus (and other species in the phylum Gordiacea)
Order & Family: Order Gordioidea, family Gordiidae
Size: Typically 10 to 30 centimeters (roughly 4 to 12 inches) in length, but can grow longer.
Natural Habitat
Found in both aquatic and damp terrestrial environments, often in puddles, water troughs, or near swimming pools.
Diet & Feeding
The adults do not eat; they focus solely on reproduction. Larvae are parasites inside insects like crickets or grasshoppers, absorbing nutrients from their hosts.
Behavior Patterns
Life begins as an egg which hatches into larvae that are eaten by host insects. They develop inside their host and, once mature, they manipulate the host's behavior to find water. They emerge from the host into water to mate and lay eggs.
Risks & Benefits
They are harmless to humans, pets, and plants. They provide a minor benefit to ecosystems by naturally controlling the populations of some common insect pests like crickets.
Identified on: 12/28/2025