Flindersine, an alkaloid isolated from Toddalia asiatica, was evaluated for their antifeedant, larvicidal and growth inhibitory activities against Helicoverpa armigera, Spodoptera litura and larvicidal activity against vector mosquitoes Anopheles stephensi and Culex quinquefasciatus. For this, leaf disc no choice method was used for agricultural pests; larvicidal activity was tested on second and fourth instar larvae for mosquitoes at different concentrations. Flindersine showed antifeedant, larvicidal and growth inhibitory activities against H. armigera and S. litura and larvicidal activity against vector mosquitoes An. stephensi and Cx. quinquefasciatus. It showed high regression (R2) values of 0.91 and 0.87 against H. armigera and S. litura, respectively for antifeedant activity. Flindersine exhibited more than 65% larvicidal activity against both the pests with LC50 values of 443.04 and 568.88 ppm and R2 values of 0.87 and 0.90 against H. armigera and S. litura, respectively. The larval and pupal duration of tested insects increased to more than five days at 1000 ppm when compared with the control. The adult emergence was reduced when the concentration of flindersine was increased. At 1000 ppm, no adult emergence was observed in both the pests. Flindersine exhibited 100% larvicidal activity against both the tested mosquitoes at 20 ppm concentration, which showed LC50 values of 2.90, 4.19, 1.68 and 2.71 ppm for 2nd and 4th instar larvae of Cx. quinquefasciatus and An. Stephensi, respectively. High regression values were observed for antifeedant, larvicidal and growth inhibitory activities. Flindersine could be used to develop an ecofriendly pesticide formulation to control the agricultural pests and vector mosquitoes.