This paper summarizes our experience in using a component model to help at construction of agents for agent-based simulations. In this model, named MALEVA, components encapsulate various units of agent behaviors or activities (e.g., follow gradient, flee, mate, reproduce). Among its specificities, it extends the principles of software composition to the specification of control, through the notions of control ports and of control components. Moreover, a notion of composite component allows complex behaviors to be constructed from simpler ones. Two examples, an ecosystem of situated agents and a microsimulation, are presented. We also discuss the benefits of our model for a fine grain control of activation and scheduling.