Six of the 12 living orders of aquatic insects contain species engaged in entomophagy, but few are being harvested effectively, leading to overexploitation and local extinction. Existing practices range from including insects (e.g. dipterans) in the core diets of many indigenous peoples to consumption of selected insects as novelty food (e.g. caddisflies). Comparison of nutritional worth of aquatic insects to the human diet and to domestic animal feed are examined. Questions are raised as to whether natural populations of aquatic insects can yield sufficient biomass to be of practicable and sustained use, whether some species can be brought into high-yield cultivation, and what are the requirements and limitations involved in achieving this?