Ageratum conyzoides, which contains various secondary metabolites such as alkaloids, flavonoids, phenols, hydroquinone, tannins, and essential oils, can be used as herbicide or insecticide. The purposes of this study were to describe the effect of methanol extract of A. conyzoides leaves on mortality of Spodoptera litura larvae and determine LC50 and LC80 of A. conyzoides methanol extract. This study used completely randomized design with two factors; concentration of A. conyzoides leaves extract (0%, 6%, 8%,10%,12%) and altitude from where A. conyzoides leaves were collected (highland, medium land, and lowland). Experiment was replicated six times. Larvae mortality rate was analyzed using ANOVA followed by Tukey multiple range tests, while LC50 and LC80 was analyzed using probit analysis. Results showed that there was significant differences of S. litura larvae mortality rate between A. conyzoides extract concentration (0%, 6%, 8%, 10%, and 12%), but no difference was found in the mortality rate between different locations. The higher the concentration of extract, mortality rate of S. litura larvae was also increased. Extract at 12% concentration resulted in highest mortality of S. litura larvae at 95%. LC50 of A. conyzoides extract was found to be 3.45-3.87%, while LC80 was 7.76-8.18%.