Horsehair worms are harmless to vertebrates, because they can't parasitize people, livestock, pets, or birds. They also don't infect plants. If humans ingest the worms, they may encounter some mild discomfort of the intestinal tract, but infection never occurs.

Can humans be infected by horsehair worms?

Nematomorapha. Approximately 350 species of nematomorphs or horsehair worms have been described, the majority (21 genera) are freshwater-type. They are long and slender worms that aggregate and copulate in the water. Microscopic larvae hatch from eggs and infect a variety of freshwater animals, in which they encyst.

Are horsehair worms bad?

Horsehair worms are not harmful to humans, domestic animals, or plants. Adult worms are free-living and non-parasitic. Immature stages are internal parasites of grasshoppers, crickets, cockroaches, beetles, and other insects and millipedes and centipedes.