These robbing screens are custom-fit to our square or octagonal hives. Stop robbing before it starts by installing these on your hives during nectar dearths, especially if you're feeding. Be sure to install in the early morning or late evening so that you don't lock out the bees that belong to the colony you're protecting. The bees need to exit the hive through the screen in order to learn how to re-enter it. This item may also be used as a mouse guard, although the entrances on our hives are already designed to protect against mice.