[3] Microscopic features include a diagnostic character of the family, both Gordius and genus Acutogordius, the postcloacal crescent of the male, a fold in the cuticle curving around the back side of the cloaca.

The adult overwinters in soil and debris and the female enters a water body such as a swamp or a stream to lay eggs.

[4] Once ingested by the insect the worm larva penetrates the gut wall and develops in a cyst in the tissue outside.

When worms are expelled from the gastrointestinal tract, their mode of entry was likely ingestion of contaminated food or water, or of an infested insect.

When present in the urine, the worm may have entered the urethra from the anus or while the victim was swimming in contaminated water.

Horsehair worms are not considered pathogenic or parasitic on humans and their presence in the body is incidental.