Abstract: A stochastic individual-based model called COSMOS was developed to simulate the epidemiology of Cosmopolites sordidus in banana fields, based on simple rules of local movement of adults, egg-laying of females, development and mortality, and infestation of larvae inside the banana plants. The biological parameters of the model were estimated from literature. The model was validated at the small-plot scale. Simulated and observed distributions of attacks were similar in twelve out of 18 plots (Kolmogorov-Smirnov test). An exhaustive sensitivity analysis using the Morris method, showed that dispersal and demographic parameters of adults were the most influent parameters.