Re: Top Entrances and Robbing?
1. Bees will not draw foundation anywhere near an opening.
2. Bees will not store honey anywhere near an opening
3. Bees will store pollen throughout the honey supers
1. Upper entrance protects from some predators
2. Upper entrance is less likely to be covered by snow
3. Upper entrance exhausts water vapor in winter
I gave up on permanent upper entrances 35 years ago when I determined that skunks never bother my bees and we never get enough snow to worry about. I do however maintain a small upper entrance that allows moisture to escape in winter.
I also tried using Cloake boards as entrances similar to the graphic J. Clemens posted. These work pretty well though they still suppress wax building a bit. If the Cloake board is used for a few months in spring then removed, it is an excellent tool for producing queens.
NW Alabama, 46 years, 24 colonies and growing, sideliner, treatment free since 2005, 14 frame square Dadant broodnest