Faecal pellets were collected under one maternity colony of each of E. serotinus (E.s.) and E. nilssonii (En.). The distance between the colonies was 83 km. In total, 325 pellets (13 samples) of E.s. and 150 pellets (6 samples) of E.n. were analysed. Nematoceran Diptera, mainly Chironomidae, were life most frequent food items in both species. Coleoptera, Lepidoptera, Heteroptera (Corixidae, Lygaeidae) and Hymenoptera (Formicoidea, Ichneumonidae) were common in E.s., Lepidoptera, Heteroptera (Miridae), Aphidomorpha, Psyllomorpha and brachyceran Diptera were common in E.n. If the samples of the two species are adjusted to the same tune (16 June - 15 August), the prevalence of Coleoptera and Hymenoptera in E.s. and Heteroptera and Lepidoptera in E.n. are highly significant (p < 0.001) while the prevalence of Brachycera in E.s. is less significant (p < 0.05) and the difference in consuming Nematocera insignificant. At that time of year, potential prey niche overlap between the two species (Ojk) fluctuated between 6% and 80% with all average of 69%. Prey diversity (H'), evenness (J'), measure of niche breadth (B) and the representation of four major insect groups varied seasonally and in the two species independently of each other. Both species prefer aerial hawking and hunt for swarming insects if available. Comparison with data of other authors revealed regional differences in foraging and diet within each of the species studied. Nutrition; Diet; Feeding behaviour; Land zones; Palaearctic region; Eurasia; Europe Eptesicus nilssonii; Eptesicus serotinus (Vespertilionidae ); Prey; Invertebrata; Composition, evidence from faecal analysis; Foraging; Foraging strategy; Czech Republic; Moravia; Prey composition & foraging strategy no species none