Distribution of fleas by their rodents hosts was investigated by field experiments using the method of individual labeling both the parasites and the hosts. The experimental site was situated in sand landscapes of the northwestern Precaspian region. Pattern of the contacts between rodents leading to the exchange of their ectoparasites was established. Average distance of the rodent migration from the site of its previous record was 54 m, while the distance of flea transfer for the same period was 142 m. The probability of host exchange by a flea under under its periodic attacks on host amounted to the value 0.500-0.889. The parameters of flea spreading in the northwestern Precaspian region and in the sand landscapes between Volga and Ural were shown to be similar. The ability of the flea Xenopsylla conformis to parasitizing on social vole without a significant decrease of its abundance was revealed.