I agree with Dave in that my first year I saw wasps actively poking around in the bee boxes in the Fall....long after there were any solitary bees nesting. It's best to remove the tubes once Summer ends, just to get them away from possible invaders. You don't want to bring them into a warm house though in the Fall- perhaps make a varmint-proof container with plenty of air vents or openings and place it on a safe shelf in an unheated garage or shed. I have an unheated garage shelf to store mine after nesting time. Once winter approaches you can then store in same cold garage or in your fridge veggie drawer like I do, at about 35-45F.