Living Web Farms on You Tube has excellent series of videos about BSF (Black Soldier Flies) and the use of their larvae (BSFL) for feed or just as an excellent composting method. I have them growing in MN, in an enclosed but unheated area, with some insulation the have stayed alive so far. At times they seemed dead, media they are in seemed at least semi frozen, but with heat they have perked back up. But the longest they have gone without getting warmed up is a night or two. At times they are going dormant for sure. I had some adult flies emerge in my reptile's tank, moved them to a bin inside his tank and they laid some eggs. It is an experiment in progress borne out of a need for live food for our pet bearded dragon who will have nothing to do with dried(dead) insects, nor will he eat pellets, so having live food on hand for him is necessary.