Insect pests inflict damage to humans, farm animals, and crops. Human and animal pests put more than 100 million people and 80 million cattle at risk worldwide. Plant pests are the main reason for destroying one fifth of the world's total crop production annually. Anopheles stephensi is the major vector of human malaria in Middle East and South Asian regions. Spodoptera litura is a polyphagous pest of vegetables and field crops. Because of its broad host range, this insect is also known as cluster caterpillar, common cutworm, cotton leafworm, tobacco cutworm, tobacco caterpillar, and tropical armyworm. The toxic effects of methanolic extract of Senna alata and microbial insecticide, Bacillus sphericus, were tested against the polyphagous crop pest, S. litura (Fab.), and the malarial vector, A. stephensi. Results from the present study states that B. sphericus is more toxic than S. alata to both the crop pest and mosquito. The malarial vector, A. stephensi, was found to be susceptible than the crop pest, S. litura. Both the botanical and microbial insecticide showed excellent larvicidal, pupicidal, longevity, fecundity, and growth regulatory activities. Median lethal concentrations of B. sphericus and methanolic extract of S. alata observed to kill the third instar of S. litura were 0.52 and 193.09 ppm and A. stephensi were 0.40 and 174.64 ppm, respectively.