Caenorhabditis remanei was found in association with the terrestrial isopod Trachelipus rathkii at several wooded locations in southwestern Ohio. These associations were as developmentally arrested dauer larvae. The sites of association were the inner surfaces of the dorsal plates and ventral appendages. C. remanei associations also were observed with Armadillidium nasatum, Cylisticus convexus, and Porcellio scaber. They were not observed with Porcellio spinicornis even though P. spinicornis populations were intermingled with infested populations of T. rathkii. Consistent with the observed natural associations, C. remanei dauers were experimentally able to infest T. rathkii and P. scaber . Dauer larvae responded to confinement with isopods by nictating and by climbing upon these potential hosts. Experimental infestations were able to persist for at least five days. Long-term infestations were not attempted.