This species is a parasite of the beetle Popillia japonica, which is native to Japan, but has been introduced accidentally elsewhere, presumably via plant trade. The nematode parasite has been identified in Popillia japonica specimens from Italy (Mazza et al. 2017), thus indicating that populations of Popillia japonica can be infested with their nematode parasite even outside of their native range. Popillia japonica has also been reported from Germany; although these German species have not yet been investigated for nematode parasites, and therefore Hexamermis popilliae has not yet been reported from Germany, the data from Italy suggest that the nematode could co-occur with its host in Germany, as well.