Objective:To investigate the mosquito larvicidal activity of Cayratia trifolia(L.)Domin(Vitaceae:Vitales)(C.trifolia)which is distributed in many parts of India with medicinal properties as vector control is facing threat due to the emergence of resistance to synthetic insecticides.Methods:Young and mature leaves of C.trifolia were investigated for larvicidal activity against3rd instars larvae of Culex quinquefasciatus in different seasons throughout the year.The active fractions were extracted using six different solvents in a non-polar to polar fashion viz petroleumether,benzene,chloroform:methanol(1:1 v/v),acetone,absolute alcohol and distilled water.Dose dependent mortality was recorded against each solvent extract.Determination of LD_(50)and LD_(90)were executed through log-probit analysis using the most bioactive fraction.The fluctuations in mortality were statistically co-related through ANOVA analyses concerning different seasons and types of leaves as random variables.Justification of larvicidal activity was established through student’s t-test.Costing effects were evaluated on the non-target water fauna under laboratory conditions.Thin layer chromatographic techniques were performed for phytochemical analysis and categorization of chemical personality of the active fractions using the most effective solvent extract following standard methods.Results:Significant variations in mortality rate were noted with respect to the type of leaves(mature and senescence),concentration of leaf extract and between seasons.The water extract among all the solvent extracts was found to induce cent percent mortality at 50 mg/L in test mosquito species within 24 h with a LD_(50)and LD_(90)value of 10.70 mg/L and 27.64 mg/L respectively.No significant mortality was recorded in non-target water population.Chromatographic analyses of the water extract revealed the presence of steroids,triterpene glycosides,essential oil,phenolics and diterpenes as secondary phytochemicals.Conclusions:Water extract of C.trifolia leaf promised as a cost effective and potent larvicidal agent against Culex quinquefasciatus. Objective: To investigate the mosquito larvicidal activity of Cayratia trifolia (L.) Domin (Vitaceae: Vitales) (C.trifolia) which is distributed in many parts of India with medicinal properties as vector control is facing threat due to the emergence of resistance to synthetic insecticides. Methods: Young and mature leaves of C.trifolia were investigated for larvicidal activity against3rd instars larvae of Culex quinquefasciatus in different seasons throughout the year. The active fractions were extracted using six different solvents in a non-polar to polar fashion viz petroleumether , benzene, chloroform, absolute alcohol and distilled water. The Dose dependent mortality was recorded in each solvent extract. The determination of LD_ (50) and LD_ (90) were performed through log-probit analysis using the most bioactive fraction. fluctuations in mortality were statistically co-related through ANOVA analyzes concerning different seasons and types of leaves as random variables. Justific ation of larvicidal activity was established through student’s t-test. Costing effects were evaluated on the non-target water fauna under laboratory conditions. Thin layer chromatographic techniques were performed for phytochemical analysis and categorization of chemical personality of the active fractions using the most effective solvent extract following standard methods. Results: Significant variations in mortality rate were noted with respect to the type of leaves (mature and senescence), concentration of leaf extract and between seasons. water extract among all the solvent extracts was found to induce cent percent mortality at 50 mg / L in test mosquito species within 24 h with a LD 50 and LD 90 values ​​of 10.70 mg / L and 27.64 mg / L respectively. No significant mortality was recorded in non-target water population. Chromatographic analyzes of the water extract revealed the presence of steroids, triterpene glycosides, essential oil, phenolics and diterpenes as secondary phytochemicals. Confusions: Water extract of C.trifolia leaf promised as a cost effective and potent larvicidal agent against Culex quinquefasciatus.