We conducted experiments to evaluate the effects of soluble components of senescent leaf material and microbial inoculum on the growth and development of the eastern tree-hole mosquito, Ochlerotatus triseriatus (Say). In the first experiment, 1g oak leaf packs that were either leached for three days to remove the labile nutrient fraction, or were not leached served as basal nutrient inputs. Prior to addition of larvae, leachate was added at 0, 10, 50, or 100% of the total water volume in each microcosm as part of the factorial design. Bacterial productivity (as measured by leucine incorporation rate) and adult mosquito biomass were significantly higher in microcosms containing unleached leaf packs compared with leached leaf packs. Adult emergence was consistently greater in microcosms with unleached leaves compared with those containing leached leaves regardless of soluble additions. However, additions of leachate to leached leaf treatments enhanced adult production, suggesting it restored the nutritive value of that treatment group. In the second experiment, mosquito development time decreased and adult mass increased in microcosms that received an inoculum of tree-hole water compared to microcosms receiving inocula of filter-sterilized tree-hole water or distilled water. In addition, bacterial abundance was higher on leaf surfaces in microcosms receiving the unsterilized tree-hole water compared with the other inoculum treatments. Thus, the observed mosquito growth responses can be attributed to microbial growth, rather than the contribution of dissolved organic matter or nutrients. Collectively, these results underscore the importance of leaf quality and microbial biomass to bacterial and mosquito productivity.