Arrenurus globator is a water mite distributed widely throughout Europe. The morphology of larval A. globator is descibed. The parasitological behaviour of the species turned out to be extraordinary variable. The host spectrum is substantially broader than for the other well-known species of the family Arrenuridae. Observations made in the laboratory and in the field demonstrated that the parasitic stage can successfully be spent on nematocerous larvae and imagines as well as on the larvae of different coleopteran families. Depending on the host species, the life cycle of A. globator is either totally subaquatic or the tha larva goes through a supra-aquatic stage on an aerial host. The factors on which the host choice are dependant are still unknown. The known hosts of the species are reviewed. Arrenurus globator can be regarded as a host generalist.