iddee, and for others, to what iddee said, i do find sometimes that the bees will propolize the notch in the front of the inner cover, (my notch is much wider 3-3 1/2") or the hole in the inner cover to their liking.......don't scrape it out or remove the propolis, cuz they WILL fill it back in. i let them do it. they know better than me their needs for ventilation and circulation/heat and air cooling.