Emergence of resistance among mosquitoes is recent problem. In the present study, was mosquito larvicidal activity of synthesized silver nanoparticles (Ag NPs) 3,5-di-t-butyl-4-hydroxyanisole isolated from Cynodon dactylon against the first to fourth instar larvae dengue vector, Aedes aegypti and filariasis vector, Culex quinquefasciatus (Diptera: Culicidae) was carried out. The synthesized Ag NPs were characterized by UV, XRD and HR-TEM. The HR-TEM analyses were spherical shaped. The highest mortality of synthesized Ag NPs tested against first to fourth instars of A. aegypti (LC50 =2.50, 2.78, 3.02, 3.05 μg/mL; LC90 = 8.28, 7.47, 8.13, 8.74 μg/mL) and C. quinquefasciatus (LC50 = 2.75, 3.00, 3.21, 3.48 μg/mL; LC90 = 6.45, 7.72, 11.06, 12.83 μg/mL), at 10 μg/mL, respectively. Synthesized Ag nanoparticles were effective as potential anti larvicidal agent against Aedes aegypti and Culex quinquefasciatus mosquitoes.