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Horsehair Worm | Daily Animal Facts

Animal profile

Horsehair Worm

GordioidaFreshwater streams, ponds and puddles as free-living adults; inside arthropod hosts as larvae

Field profile

Horsehair worms are long, thin nematomorphs whose juveniles develop inside crickets, grasshoppers and beetles. Adults are free-living, do not feed, and exist only to reproduce. They are frequently found writhing in water troughs and swimming pools, which gave rise to their folk name.

Scope note

This is an editorial profile, not a diagnostic field-identification guide or a substitute for current conservation assessments. Follow the cited sources on each fact for the evidence trail.

Published field notes

2023-07-14

Horsehair Worm

Horsehair worms send their hosts toward water

A mature nematomorph must reach water to breed, but its cricket host has no reason to go there. Infected crickets are markedly more likely to enter water, where the worm emerges and swims away.

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