Cesar asks about over-wintering 5-frame nucs in Styrofoam nucs. I regularly over-winter 5-frame nucs, without difficulty. Depending on where in Colorado you live, our winters here are probably as cold as your own, but we might have less snow. We average about one meter (39 inches) a year of snow, and usually have at least one consecutive week where night temperatures are at least -20F. Being covered with snow does not hurt the nucs, and may help them by providing better insulation. I think it is critical that they be packed out with sealed honey and pollen by mid-October. I use Carnolian stock and think they winter better as nucs than Italians. Upper ventilation is critical and I use two 1" holes screened from the inside. I have never tried Styrofoam, but know of others who have. The Styrofoam nucs I have seen are very tight and I would worry about that. Bees must have upper ventilation, or they will die. I suggest you either find a way of propping up the cover or drill small holes. I have tried holes as small as 1/8", and they have been successful. Best of luck, Lloyd Lloyd Spear, Owner, Ross Rounds, Inc. The finest in comb honey production. www.rossrounds.com