Mouse guards are a combination of 3 metal plates.
The two smallest plates are called nail plates, while the larger plate is called the mouse guard plate.
Mouse guards are easiest to install when your first assembling your hive, but can also be installed later in the year when you have bees in the hive already.
To install the mouse guard, you'll need 6 of the larger nails from the bag you received to assemble your hive.
If it's later in the year and you already have bees in your hive, we recommend using screws and a drill instead of a hammer because it is less likely to disturb your bees.
Once you've installed your nail plates, you can easily insert or remove the mouse guard plate whenever you'd like.
The First Purpose of a Mouse Guard
The reason you purchase a mouse guard is obvious -- to keep mice out while still letting bees in.
Some may ask, are mice really an issue?
The answer is a resounding yes!
What mouse wouldn't want access to an abundance of honey and heat during the winter?
Not only will mice eat your honey, but they'll destroy your comb.
To many beekeepers, yes, the honey is important, but the beeswax comb is considered to be one of the most valuable assets you have.
A frame of drawn comb can last for decades. Year after year, you'll uncap and drain the honey from the frames while the beeswax goes on relatively undamaged.
Since the bees can reuse this comb, they don't have to constantly draw it out. This allows the bees to spend more time focusing on collecting pollen/nectar and making honey rather than building comb with their beeswax.
Your bees spend more time than you think on building comb. In the first year, comb-building takes up a large majority of their time. This is why you shouldn't take honey from a first-year hive.
When a mouse comes into your hive and destroys your comb it turns hours and hours of work that your bees did into a meaningless pile of beeswax crumbs.
The Second Purpose of a Mouse Guard
The other not-so-known purpose of this kind of mouse guard is to give you the ability to keep your bees in your hive.
There are a couple of unique times throughout the beekeeping year that you may want to do this to your hive.
You might find this most useful whenever you move your hive or if you live by a crop field that uses pesticides.
The night before the move or the crop field treatment, you'd put the mouse guard onto your hive with the small-hole-side facing down.
This will keep your bees in the hive while still allowing your hive to breathe.
How to Install a Mouse Guard
The best time to install a mouse guard is when you're first assembling the hive.
Hammering nails without the bees in the hive makes this process easier. Without bees, you can handle the box and flip it around as necessary. Having this ability makes installing the nail plate a breeze.
Although it is easiest to install a mouse guard during assembly, it isn't too difficult to put one on while the bees are in the hive.
If your bees are in the hive, we recommend finding/using some screws that fit into the nail plate and a drill instead of a hammer and nails. The bees aren't very fond of their beekeeper banging on their hive with a hammer, even if it is for their benefit.
Remove Entrance Reducer
If you already have bees in your hive and you're using an entrance reducer, you're going to need to remove it. You don't want it to be stuck behind the mouse guard.
It's likely the case that the bees have glued the entrance reducer in place with propolis. Use the hive tool to help you pry the entrance reducer out.
If you have a heavy hive, it may be trickier than you think to remove the entrance reducer. The weight of the hive can sometimes rest on an entrance reducer. You may have to take off the boxes in orer to remove it.
Place Nail Plate
Even if you don't use the mouse guard until late fall, it's good to put the nail plates on during assembly. Doing so will allow you to simply slip the mouse guard in when you need it.
When installing the nail plates, they should always go on the sides of the hive near the joints and never above the mouse guard plate. See what not to do (Click Here).
When installing the nail plates, you'll want the appropriate spacing.
If the nail plates are placed too wide apart, the mouse guard will fall out of the plates.
If the nail plates are placed too close to each other, the mouse guard won't be able to slide in between the plates.
To help you space the plates properly, it's important to place the mouse guard plate over the entrance and sitting on the bottom board. This will help you accurately know where to put the nail plates.
Another detail to note is that the nail plates have a "z" pattern (highlighted in green in the picture below). Make sure that the side with the holes is on the far side of the hive and that it is flush against the hive. This will leave a small gap for the mouse guard to be able to slide underneath the nail plate.
Install Nail Plate
Once you've estimated the proper spacing of the nail plate go ahead and secure the nail plate to the hive.
If your beehive doesn't have bees, you can flip your box on its end and hit the nails down into the hive. You'll use 6 of the nails that were given to you to help assemble your bee boxes.
If your beehive is full of bees, then we recommend you find/use screws that fit into the nail plate. This will minimize the amount of disturbance caused to the bees.
Slide in the Mouse Guard Plate
When the time comes to put in your mouse guard plate, you can use the tabs that protrude out from the plate to help you slide it behind the nail plates.
A good time of year to consider using the mouse guard plate is in September.
Mice usually do some scouting for their winter getaways during early fall. When they find a nice spot that they want to return to, they'll mark it with urine.
To prevent mice, you can put the mouse guard plate on before the mice can claim their spot.
The mouse guard plate will not slow down the production of your hive and may also help prevent robbing bees during this time of year.
If you are late to put on your mouse guard plate, you may want to look in the hive to make sure there's not a mouse already living in there.
If it's too cold to open the hive at this point in the year, you can take a long stick/clothes hanger and slide it in through the entrance. This should scare the mouse and it may come out of the hive.
Mouse Guard or Entrance Blocker
Earlier in the article, we mentioned the two purposes of this kind of mouse guard.
Below are two photos of what each purpose will look like after the mouse guard plate is installed.
The side that looks like a large comb with small "n" shaped openings is to allow the bees to go in and out of the hive while preventing mice from doing the same.
The side that has a lot of small holes will lock your bees inside the hive while still being able to breathe. Be sure to close off any top entrances that your hive may have.
What Not To Do
A very common mistake that beekeepers make when they are installing the nail plates is to put them on above the mouse guard plate. See picture below.
While the nail plates still effectively hold the mouse plate in place, there are a couple of issues that are underneath the surface.
The nails from the nail plate may have penetrated through not only the box but also a frame or two. While you may not have noticed it now, you will when you try to inspect your hive and the frame won't come out.
A second issue that comes from this mistake is that you have to lift the boxes to be able to slide the mouse plate in and out from under the nail plates. This is very inconvenient, especially given how heavy your hive will be in the fall when you decide to put the mouse plate on.
Installing the mouse guard is just one of the many tasks to prepare your bees for winter.
It can end up saving hive's honey but, even more importantly, its beeswax.
It's recommended to have this step done before September.
Doing so will keep your hive off the market while mice are scouting for their winter homes.
Good luck out there!
Continue Your Bee Journey!
The following articles could be very helpful in taking your next steps.
Recommended First Hives
If you haven't yet purchased your first hive, we recommend one of our Starter Hive Kits. Each kit comes with all the essential parts of a beehive and the accessories you'll need for your first few years of beekeeping. We consider them "Nuc Ready" which means they come with 5 frames and are ready for the 5 that you buy when you purchase a 5-Frame Nuc of bees.