Fleas are influenced not only by host characters, but also by characters of the off-host environment.  Consequently, a habitat of a flea can not be just a particular host, but a particular host in a particular habitat.  Therefore, habitat selection in fleas can be considered at different scales (within an individual host, among host individuals within a host species, among host species within a host habitat; and among host habitats within host species).  In this paper, we attempt to address a number of problems related to habitat selection in parasites on the model of rodents and fleas and to demonstrate some examples based on the studies carried out in the central Negev desert of Israel.  We consider the factors that determine habitat selection and, consequently, the distribution and abundance of parasites in terms of relationships between rodents and their fleas as follows: intrinsic processes in the parasites; direct effects of the hosts on the parasites and of the parasites on the hosts; direct effects of the environment on the parasites; and effects of the hosts on the parasites mediated via environment.