The black soldier fly (BSF; Hermetia illucens L.; Diptera: Stratiomyidae) has been studied for its capability to convert organic waste to high quality protein, control certain harmful bacteria and insect pests, provide potential chemical precursors to produce biodiesel and for its use as feed for a variety of animals. Nutritional value of BSF larvae is discussed, as well as the effect of biotic and abiotic factors on both larval body composition and performance. Although BSF larvae contain high protein levels (from 37 to 63% dry matter; DM), and other macro- and micronutrients important for animal feed, the available studies on including BSF larvae in feed rations for poultry, pigs and fish suggest that it could only partially replace traditional feedstuff, because high or complete replacement resulted in reduced performance. This is due to factors such as high fat content (from 7 to 39% DM), ash (from 9 to 28% DM), and consequences of processing. Therefore, further studies are needed on nutrient composition, digestibility and availability for target species and on improved methods to process larvae, among other aspects. Additionally, it is clear that factors including quantity and quality of food, temperature, substrate moisture and/or larval crowding can affect BSF performance. However, the biology of BSF, in particular of the adult stage, has not been studied in detail. This review provides background information on the nutritional value of BSF larvae, its suitability as animal feed, biotic and abiotic conditions that affect its performance, and identifies which knowledge is required to ensure more dependable yields of BSF-mass rearing and development of economically feasible methods to take advantage of this species as animal feed.