The taxonomic position was examined of three isolates, MTCC 3249T, SH and SLH, from the midgut of female Culex quinquefasciatus and Aedes aegyptii mosquitoes. Numbers of cells of these isolates increased 2000-fold after a blood meal of the mosquitoes. 16S rRNA gene sequence analysis of the novel strains showed that they were highly homologous to strains of Aeromonas. DNA-DNA hybridization studies showed that DNA of strain MTCC 3249T was 96 and 88% similar to that of strains SH and SLH, respectively, and showed 54% relatedness to Aeromonas jandaei and 61% relatedness to Aeromonas sobria, which is below the cut-off value for species differentiation. The biochemical profiles of all three novel strains were identical. On the basis of a polyphasic approach using phenotypic analysis, 16S rRNA gene sequencing and DNA-DNA hybridization studies, a novel species is proposed for these isolates, Aeromonas culicicola sp. nov., with the type strain MTCC 3249T (= NCIM 5147T). Isolation of A. culicicola from the midgut of mosquitoes might help to explain the origin of Aeromonas infections caused without exposure to contaminated water, soil or food.