Hermetia illucens individuals were reared at the entomological facilities of the University of Milan (45°28'33.9N, 9°13'39.9E). The Black Soldier Flies (BSFs) used in this work originated from a laboratory stock culture of H. illucens that was retrieved from a compost container in Lombardy, Northern Italy (45°19ʹ54ʺN, 9°05ʹ58ʺE); refer to Jucker et al., 2017, doi:10.1093/ee/nvx154. Insects were reared on three different diets: a full nutrient (FN) diet, composed by 50% wheat germ, 30% alfalfa, and 20% corn flour, to which an equal volume of water was added; a nutrient restriction fruit (NRF) diet formed by mixing fresh apples, pears and oranges (33.3% each); and a nutrient restriction vegetable (NRV) diet composed by fresh green beans, cabbage and lettuce (33% each). In the laboratory, the BSF eggs were transferred into plastic containers (10.5 × 5 cm), with metal mesh to allow air exchange. To each of the containers one of the diets (FN, NRF or NRV) was added for a total of 3 containers per diet. These containers were kept in a climate chamber under controlled conditions (temperature: 25°C ± 0.5°C; relative humidity: 60% ± 5%; photoperiod: 12:12 light:dark). The larvae were provided ad libitum access to the three diets for up to 83 days (UNTIL PUPAE EMERGED?). Wet mass was determined of groups of 10 individuals usually every 2-3 days.