Paragordius varius is a parasite species in the horsehair worm group (Nematomorpha).

The definitive hosts are mainly terrestrial arthropods, most often carabid beetles, crickets and praying mantids.

[3] Paragordius varius have a slightly off-center mouth and distinct grooves running along its cylindrical body.

Adult worms emerge from their insect hosts late spring or summer.

[5] Once the sperm lands, a large circular glob forms which passes into the seminal receptacle of the female within twenty four hours of mating.

Upon conception, the female P. varius lays a long, white, string of eggs and dies.

[3] The life cycle of nematomorphs has 4 stages: First is the egg, which takes about 10–12 days to complete its larval development after being laid.

The final stage of the nematomorphs is the free-living aquatic adult; the development only takes about thirty days where the P. varius is able to produce three generations in one year.

Amongst the host species are grasshoppers, crickets, cockroaches, snails, mosquito larvae, or other small aquatic animals and insects.

In the definitive cricket (Acheta domesticus) host P. varius can reduce the time spent calling of males.