Horsehair Worm
Scientific Name: Gordius spp. (or generally in the phylum Nematomorpha)
Order & Family: Order: Gordioidea, Family: Gordiidae
Size: Typically 4 to 14 inches long (10-35 cm), but extremely thin (1-3 mm in diameter).
Natural Habitat
Adults are free-living in freshwater environments like puddles, troughs, swimming pools, and damp soil. Larvae are internal parasites of arthropods.
Diet & Feeding
Adults do not feed; they rely on stored energy. Larvae are parasitic and absorb nutrients from their insect hosts (crickets, grasshoppers, beetles, roaches).
Behavior Patterns
They are famous for their parasitic lifecycle where the larvae develop inside a host insect. When mature, they chemically manipulate the host to seek water, where the adult worm bursts out to reproduce. They are often seen twisting into intricate knots, earning them the nickname 'Gordian worms'.
Risks & Benefits
Harmless to humans, pets, and plants. They do not bite or sting. They can be considered beneficial as they help control populations of pest insects like roaches and grasshoppers.
Identified on: 2/21/2026