The entrance of a hive is usually at the bottom. In most designs, there is a floor placed immediately below the brood box, where the queen lives. The floor is open to the front to let the bees come and go. However, most beekeepers use an entrance reducer (click here for a selection from Amazon) to limit the area that is available for bees from other colonies, wasps, moths, and other pests, including mice, to enter the hive and cause havoc.
In general, it is probably best to keep an entrance reducer on the hive all year round. This is so that the bees will recognize the front of their home hive. It is possible to move the reducer outwards to open up more space for the bees to forage at the peak time of year.
Just as there are many designs for hives, so there are many for entrance reducers. Most commonly they are a length of wood with a big opening scooped out in the center or to one side.
One of the reasons for using a reducer is that the entrance is usually only busy for six to eight weeks in a year, which coincides with when local plants are in flower. This is when there is a lot of nectar to collect and when the bee population is at its largest.
Protecting the Hive
The hive is protected by guard bees. Most of the time when nothing is troubling the colony you will not see any guard bees at the entrance. But if you knock the hive then a few will appear. If they do not see what is causing the disturbance, a couple will fly around to see if any action is needed.
When the guard bees are at the entrance, they will challenge other bees entering the hive. Bees from the colony all have the same smell because of recognition pheromones. However, drifting worker bees from other colonies will smell different and will therefore be challenged. Because the drifting bees are carrying pollen and nectar and have confused this hive for their own, they react passively to the challenge. The guard will let them go, but they will be challenged several times. At this stage, the pheromone secretion of the guards will have rubbed off on the offending bee and it will then join the colony.
However, if a bee that hopes to enter the hive and steal honey is accosted, the reaction will be more aggressive and a fight is likely, with one or both ending up dead. The same happens to wasps. The guards are normally alerted to raiders and wasps by their zig-zagging flight across the entrance as they seek a way past the guards. If the interlopers were to be successful at gaining entry, then the colony will be at risk.
Using an Entrance Reducer
Ron Brown, in his Seasonal Guide to Beekeeping, recommends using a screw at one side so that the block can be swung open during the honey flow and pushed back at the end of the summer when the risk of raiding is greater. He also uses a design where some nails are inserted into the hole in the reducer to prevent mice from entering the hive.
One advantage of using a reducer is that it helps to protect a weaker hive from raiding or wasp attack. The fewer the bees there are in a colony, the harder it will be to defend a wide opening.
Reducers in winter also help with keeping out draughts. Some beekeepers advise turning the reducer upside down so that the hole is at the top and does not become blocked.
Another time to use a reducer to completely block the entrance is when you want to move a colony. Or when you are using treatments inside the hive to control mites.
Dancing Outside the Entrance
When the worker bees are young, they go out on play flights. These tend to happen on warm afternoons and the bees all have a habit of flying at the same time, which creates a lot of noise. The beekeeper will see them flying in circles of ever-increasing size.
The young bees fly out backwards, looking back at the entrance to the hive and the area in which the hive is situated. Bees have a particularly good memory for what the front of the hive looks like and can be confused if the picture changes. For example, if you let the grass grow up in front of the entrance and then cut it down, they will spend a lot longer returning the hive.
What this is telling you is that you want to make as few changes to the appearance of the hive as possible.
While looking at the entrance, the beekeeper should get used to the appearance of the bees. If there are any changes, that can be a sign of trouble. For example, foraging bees tend to fly straight in and straight out. The number of bees that you see is another factor to consider.
Types of Reducers
Reducers can be made from metal, plastic, or wood. Some of the wooden bars have two openings scooped into them, one small and one large so that you can make adjustments through the year.
Some beekeepers use a metal strip with holes in it to ensure that mice cannot enter the hive during the winter. One downside to this is if it is left in the entrance when the worker bees start foraging then pollen can be knocked off the bees’ legs.