In the present study, we investigated the prevalence and intensity of Hectopsylla pulex
infection in Molossus rufus
and Molossus molossus
, the parasite's choice of attachment site, and whether this host-parasite system varies with host size. Twenty-four bats were captured by hand from the roof of a house in Southeastern Brazil. M. rufus
exhibited a prevalence of 71.4% and the mean intensity averaged 5 ectoparasites per bat. M. molossus
exhibited a prevalence of 90%, and the average mean intensity was 2.11 ectoparasites. The attachment sites were: ear, tragus, shoulder blade and tibia, anus, wing, axilla, mouth and dactylopatagium. A positive correlation was observed between the bats' weight and the number of fleas.