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Extension > Garden > Diagnose a problem > What insect is this? > Garden Pests > Insect relatives: Spiders, millipedes, centipedes, sowbugs, etc. - 2 inches and larger > Horsehair worms

Horsehair worm
Photo Credit: Gary Averbeck

Horsehair worms
Phylum Nematamorpha
Size: 2 up to 14 inches long

Where/When: They are found in freshwater or damp soils or surfaces, such as on plants.

Significance: They are parasites of insects, arthropods, and other invertebrates when they are immature and free-living as adults. Despite their appearance, they are harmless to people and plants.
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