Hi Joe,
Larvae are used as in this phase most insects with complete metamorphosis feed and store nutrients and energy for their development and reproduction during the adult phase, in the case of BSF the adults do not feed during the adult phase, so they don't carry pathogens to food, I have been rearing BSF for more than a year and I have seen once one entering my house and as soon as it got in it tried to exit through the window, so even in case of a high population density the risk of contamination is low and BSf are not a nuisance.
