In discussing his new polystyrene hive, Bob said "This allows for a lot of air circulation through the bottom, and hence through the Varroa screen. I am worried that there may be to much cold air on the new package during our cold spring nights." Bob, save yourself any worry, or effort in modifying the bottom. I am slightly north of you, and use bottoms that are almost 100% screens (1/4" hardware cloth) all winter, spring, summer, etc. Moreover, I know another nearby beekeeper who has been doing so for over 40 years! The increased draft that has you concerned does not harm the bees and, under certain conditions, may even be beneficial! Lloyd Lloyd Lloyd Spear, Owner of Ross Rounds, manufacturer of comb honey equipment for beekeepers and Sundance pollen traps. http://www.rossrounds.com [log in to unmask]