Insects of order Odonata regarded as "very beneficial insects" as the large sized larvae of dragonflies and damselflies prey upon the smaller sized larvae in aquatic habitats. At the immature stage of mosquitoes, they are easy to capture as prey as they are less mobile and remain concentrated at a place. Damselfly and dragonflies are important predators of many micro invertebrates including mosquito larvae in their larval stages. Here, in this study, I am focusing mainly on the 12th instar of B.geminata and its predation on mosquito larvae as prey preference. According to the recorded data, it is clear that B.geminata larvae were found to consume mosquito larvae in significant number. One instar of B.geminata could consume up to 15 mosquito larvae in one hour from the beginning of the experiment and up to 50 larvae in 48 hours. The main reason of this study is to help to stop the transmission of mosquito borne diseases through bio controlling agents. From the results, it is evident that 12th instar of B.geminata can consume enough larvae of A.culicifacies and it also needs to be experimented in their natural field conditions.