Energy consumption, network lifetime and coverage are the major challenges in wireless sensor networks. This study proposes a method that grids network area into square cells on a geographical basis. The node possessing the highest energy is selected as an aggregator in each cell. Given the cover area and remaining energy, the firefly algorithm functions to select and actively maintain the most suitable node in each cell while deactivating others. The uniqueness of the proposed evolutionary firefly algorithm is to ensure the desirable and effective network coverage. Omnet++ was applied for simulation study, the results of which were compared with those from both TCO and ACO-Greedy models. A significantly greater coverage was provided by the proposed method with fewer nodes and 30% decrement in energy demand. The added advantage was the elongation of network lifetime.