This book presents a broad view of the ecology and behavior of aquatic insects, raising awareness of this conspicuous and yet little known fauna that inhabits inland waterbodies such as rivers, lakes and streams, and is particularly abundant and diverse in tropical ecosystems. The chapters address topics such as distribution, dispersal, territoriality, mating behavior, parental care and the role of sensory systems in the response to external and internal cues. In the context of ecology, it discusses aquatic insects as bio indicators that may be used to assess environmental disturbances, either in protected or urban areas, and provides insights into how genetic connectivity can support the development of novel conservation strategies. It also explores how aquatic insects can inspire solutions for various problems faced by modern society, presenting examples in the fields of material science, optics, sensorics and robotics.