The lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), is one of the most common insect pests in commercial poultry farms, where it reproduces within the litter floor, feeding on poultry manure, spilled feed and other organic material. It can also infest, feed and reproduce on stored grains and related amylaceous commodities. Its significance is related mostly with the fact that it serves as reservoir and vector for many pathogens that cause serious diseases, such as Salmonella, Escherichia and various viruses. Recently, A. diaperinus attracted a lot attention as it was listed in the EU Regulation 2017/893 among the insect species that are allowed to be used for the production of insect meal as aquafeed ingredient, changing our perspective on this insect from a noxious pest to a potential nutrient source. This is the first review on A. diaperinus summarizing the significant recent findings in its biology and control. Moreover, this review aims to provide a helpful tool for aquaculture scientists working with A. diaperinus as aquafeed ingredient. Therefore, we gather and highlight the available data that classify A. diaperinus as a promising insect-based protein provider and we comment and discuss on the public concerns that arise from its utilization as feed.