Bees that make use of a lot of propolis will glue the hive shut for spring, for summer, and for autumn, too. Some of my colonies are gooey with propolis and some are not. I do not know what evolutionary advantage goes with lots of propolis; both gooey and non-gooey bees live in my apiaries. Do any breeders breed for or against this characteristic? Tim Sterrett Westtown, (Southeastern) Pennsylvania, USA [log in to unmask]