It is common in commercial operations to rear newly hatched black soldier fly larvae in a nursery for a few days before putting them into a bioreactor. This may involve feeding them on a special diet. As shown below, however, this is not always a good idea.

dos Santos, S.M., da Silva, F.G., Bavosa, H.R., Martins, I.P., Nascimento, J.C.S., Lemes, P.G., Nogueira, W.C.L. and da Costa, D.V., 2023. Nursery diet exclusion during the development of Hermetia illucens L.(Diptera: Stratiomyidae) in restaurant food waste. Journal of Insects as Food and Feed, https://doi.org/10.1163/23524588-20230074

The black soldier fly (BSF) (Hermetia illucens) (Diptera: Stratiomyidae) is a valuable commercial insect for its nutritional and productive aspects, ability to cycle organic waste, and use as protein in animal feed. Its rearing is done in two steps, the ‘nursery diet’, and the ‘rearing’ diet, but the nursery diet may increase costs and labour. The effect of the nursery diet time on larval performance, substrate reduction, and larval nutritional composition were evaluated to determine whether it is possible to remove this step from the BSF production process. Chicken feed was used as nursery diet and restaurant food waste for the rearing diet. The performance and chemical composition of BSF larvae with eggs inoculated directly into the restaurant food waste and incubated in the nursery diet were evaluated for six, eight, ten, and 12 days. Substrate reduction was higher for larvae raised without nursery diet. The final weight, growth rate, and number of live larvae were the same for larvae reared with or without nursery diet. Larvae reared without nursery diet had higher crude protein, lower dry matter, and ash content than larvae on nursery diet. The nursery diet did not improve most of the characteristics analysed, and the nutritional levels of the larvae. This may suggest that this step could be ignored when rearing BSF larvae on restaurant waste.