Feed protein is under pressure from every direction at once: imported soy and fishmeal supply chains, climate and land constraints, and agri-food side-streams piling up without a clear destination. Tenebrio molitor, the yellow mealworm, sits right at that intersection as a candidate for closing the loop between waste and feed. This session takes the yellow mealworm as a biorefinery, turning side-streams into vaporizable outputs from a single rearing process, and asks the question that decides whether the system pays off. Which biological levers govern yield, conversion efficiency, and product quality in mass rearing. We work through the production-relevant biology, from instar plasticity and mating design to aggregation behavior and the density thresholds where cannibalism kicks in, and then turn to environmental conditions, and feeding ecology, where recent substrate trials show that some local by-products support strong larval growth while others collapse survival outright. Substrate selection, it turns out, is a biological question, not an engineering one. The session closes with four hands-on laboratory stations, covering life-stage identification, pupal dimorphism scoring, behavioral observation, and optimal mass-rearing protocols, so participants leave having handled the biology the talk is built on, and with a working framework for thinking about rearing optimization in their own systems.