Larvae of bird blow flies are hematophagous intermittent parasites and they infect a variety of bird host species. In this study we focused on the prevalence of infestation in nests of Turdus merula in two sites with different climate. We collected 57 nests from Bratislava (Slovakia) which has a warmer climate and 37 nests from Leipzig (Germany) where there is cooler weather during the breeding season. There is no significant difference in the prevalence of infestation and in number of puparia between these two sites. The average number of infested nests was 18.68% while the average number of blow flies per nest was 10.0 ± 7.32 with 2.54 ± 1.83 larvae per nestling.