Mice are a headache for beekeepers in winter when bees are vulnerable. They enter hives seeking shelter and food but often end up causing massive disruption.
Unwanted mice use comb and frames for nests which causes serious damage. They also feed on valuable colony resources like honey, pollen, and combs. The foul stench of urine is unpleasant for beekeepers and may cause bees to abscond.
This guide looks at some helpful ways to keep mice out of the hive. You can skip down to making a homemade mouse guard if you want quick solutions.
How can I keep mice out of a hive?
While an uninvited mouse isn’t usually a problem for a strong colony, weaker colonies struggle to keep their homes pest-free. Beekeepers commonly use a mouse excluder at the entrance to prevent mice from entering. Mousetraps will add a secondary layer of protection to the hive.
As part of winterizing, thoroughly check the hive and seal any unwanted holes or gaps. We suggest reading our guide to winterizing a hive for more information and a free checklist.
What is a mouse guard?
A mouse guard is a simple piece of equipment that prevents mice, shrews, voles, and other rodents from getting into a hive. These small devices are typically made from metal and are placed in front of the hive entrance. They help deter small creatures while allowing bees to come and go as they please.
Mouse guards can prevent severe damage to the hive. Once mice enter a box, they may chew into the frames or combs to build a cozy nest. They will also make a mess of resources inside the hive, like burlap sacks to feather their nest.
What size entrance is needed to exclude mice?
Mouse guards need to be small enough to keep mice out. However, they also need to allow adequate ventilation room and space to remove dead bees and bring in pollen. Most mouse guards range from ¼” to ½” (6.35mm to 12.7mm) in diameter, with commercial products typically opting for a 3/8” (9.25mm) circle.
- There is no perfect-sized hole for a mouse guard.
- Half-inch openings give bees the room they need to go about their daily activities, but some mice will be able to access the hive.
- Quarter-inch holes will keep mice out, but problems like bees piling up the entry may be a problem if hive mortality is high during winter.
- Even with a mouse guard, rodents may access the hive through alternative entry points like ventilation holes or a damaged box.
What are the signs of mice in a hive?
Although a mouse can be hard to spot in a hive, the signs are much easier to identify. Look for frames with chewed corners and evidence of nesting materials like grass dropped onto the bottom board or left at the entrance to the hive. Mouse droppings may have been collected in the tray if your hive has a screened bottom board.
How to make a homemade mouse guard
Mouse guards are a relatively inexpensive piece of equipment sold at most beekeeping supply stores. But they’re easy to make yourself by following these simple steps. Be sure to carefully inspect for mice before adding the guard; any that you miss will be trapped inside the hive.
- Smoker (check our recommended smokers here)
- Hive tool
- ½” hardware cloth
- Staple gun
- Tip the entire hive back using a hive tool to pry the lowest brood box away from the bottom board. The hive may be heavy from honey, so we suggest getting help from an assistant to lift the hive.
- Using a flashlight, shine it under the hive to look for rodent intruders. Also, check up under the frames to ensure mice aren’t clinging to any comb to avoid detection. Use the stick to shoo away any mice.
- Use a stapler to attach a strip of hardware cloth (hardware screen) across the hive’s entrance.
This DIY mouse guard is super-easy to make, and some beekeepers choose to leave them on year-round. Check out the short video below, which shows how it’s done.
Do rats invade beehives?
Rats will seek shelter in hives during winter when food is scarce. They use a hive for warmth and happily eat comb or honey to stay alive.
To keep rats away from hives, reduce beehive openings, clean up rubbish and debris, and keep equipment well maintained.
Commonly asked questions
When is the best time to add mouse guards?
Beekeepers often install a mouse guard during their winterizing process. This generally occurs in September in the United States, as the weather cools and winter approaches.
Is a mouse excluder the best way to get rid of mice?
Mouse guards are a simple, cheap method of keeping mice out of hives, but mouse traps may be a better option. Too many dead bees through winter will plug the entrance if a guard is in place. This blockage makes it difficult for bees to get out of the hive and perform cleaning flights.
Can I use an entrance reducer instead of a mouse guard?
While entrance reducers offer some protection from rodents, these pests still threaten the colony. Mice and other vermin can enlarge the entrance by chewing their way through the wood. Mouse guards are made from materials that can’t be chewed.
Can bees remove dead mice?
Mice are too heavy for honey bees to remove from their hive. Instead, worker bees encase the predator in a propolis coating to reduce the chance of spreading disease.
Do bees sting mice?
With a sufficient population, bees can easily kill a mouse with their venom. Often, weak hives and huddling hives in winter will leave mice alone. However, as their numbers flourish, they will likely attack unwanted guests. Mice are known to move out of hives as the spring arrives and the colony multiplies.
Do mice like honey?
Mice find sweet substances like honey hard to resist, especially during winter food shortages. Its aroma will draw mice into hives from a distance.
Do shrews nest in bee hives?
While a shrew will not nest in a hive, hollow bee exoskeletons are common signs that they’ve paid a visit. They are known to remove the bee’s head and diet on its innards. Droppings are another sign that a shrew has entered the hive.
Learning how to keep mice out of a hive is valuable knowledge for beekeepers. While they’re not a big problem for strong hives, these pests can easily take down a weak one.
A mouse guard or mouse strategically positioned mouse traps will usually ward off pesky vermin. You may also like to read our guide on the correct positioning of a hive to help your bees cope with external threats.