Bat bugs are often roost ectoparasites of bats. Previous studies have shown that bats shifting roosts within the growing season prevent the massive reproduction of these parasites. We postulated that there could be other antiparasitic strategies of philopatric bats roosting in non-dwelling spacious roosts. Unfortunately, there are no studies devoted to such a topic. For 3 years, two attics highly and less infested by bat bugs (Cimex pipistrelli) with breeding females of Myotis myotis were monitored. From April, after the arrival of the bats, to November, abundance of all instars and adult bugs was sampled in the attics by adhesive traps. We found different patterns in the bug abundances and dynamics in the two attics. In highly infested attic, bat bugs induced pregnant females to move from the infested site of the attic to the non-infested one. Internal temperature and relative humidity were similar in both infested and non-infested sites. Females roosted in the infested site till time before parturition and then moved to the non-infested site within attic. When bats were absent in their old site, the abundance of nymphal instars of bugs decreased by half. Although adult bats can survive under high parasite loads of bat bugs, reproducing females prevent parasite reproduction and simultaneously reduce parasite load in the young by shifting inside spacious roosts.