This paper describes BiSNET (Biologically-inspired architecture for Sensor NETworks), a middleware architecture that addresses several key issues in multi-modal wireless sensor networks (MWSNs) such as autonomy, scalability, adaptability, self-healing and simplicity. Based on the observation that various biological systems have developed mechanisms to overcome these issues, BiSNET follows certain biological principles such as decentralization, food gathering/storage and natural selection to design MWSN applications. In BiSNET, each application consists of multiple software agents, which operate on the BiSNET middleware platform in individual sensor nodes, and each agent exploits certain biologicallyinspired mechanisms such as energy exchange, pheromone emission, replication, migration and death. This is analogous to a bee colony (application) consisting of multiple bees (agents). This paper describes the biologically-inspired mechanisms in BiSNET, and evaluates their impacts on the au...