As the cold season quickly approaches, I decided to install these mouse guards on my hive. It turned out to be a really bad idea because approx. 4 days later I went for a regular check up & found the majority to be plugged almost solid with dead bees. I think they render the undertaker task almost impossible so it ends up plugging the hive with a wall of bodies. I also noticed drones that had return for their daily mating flight stuck out at the front getting fed through the guard by workers... If you're a new beekeeper like me, don't make this mistake.