A major challenge for achieving successful mosquito control is overcoming insecticide resistance. Bacillus thuringiensis which is one of the most effective biolarvacide for control of species of mosquitoes and monitoring of larval susceptibility is essential to avoid resistance development. Mosquito larvacidal activity of Bacillus thuringiensis was assessed by isolating them from ecologically different soil habitats in and around Enugu metropolis. The isolate organisms were confirmed as Bacillus thuringiensis based on biochemical characterization and microscopic observation. The larvacidal activity of Bacillus thuringiensis isolates was tested against the larval of mosquito by using the standard cup bioassay. The isolates of Bacillus thuringiensis showed a significant level of variation in their larvacidal activity.