Everything You Need to Know About Mason Bees

In the recent bee crisis (or bee apocalypse, as some call it) everyone focused their attention on honeybees. While it was great to see the world unite and campaign in favor of the bees, most people campaigned for the wrong species. Honeybees were never in trouble, but mason bees were.

mason bees

Mason bees play an important role in our world and we should make an earnest effort to protect them. Here’s a look at their fascinating lives. I’ll also tell you how you can help them, and why you should consider keeping them.

What Are Mason Bees?

Mason bee refers to a species of solitary bee in the genus Osmia. It’s said that their genus is named for the citrusy scent mason bees use to mark their nests. They’re commonly called masons because of their nesting habits, in which they use mud and other materials associated with masonry to build their homes.

There are various types of mason bees including the red mason bee, orchard mason bee, the blueberry bee, and the hornfaced bee. Mason bees are typically found in the Northern Hemisphere, in Europe, Asia, and the Americas. More than a hundred species are found in or are native to the USA and Canada.

How to Identify a Mason Bee

It’s much easier to identify a mason bee by its behavior than its appearance. For one, as I said, there are various types of mason bees and their characteristics will differ. Listing each one’s identifying traits would be quite a task!

Some mason bees look a lot like honeybees, others can easily be confused with the common housefly. In general, they are smaller than the average honeybee and grow to about 0.3 inches. They are most commonly identified by the metallic tint on their skin.

Speaking of skin, mason bees have faint lines that appear as stripes across their skin. Unlike in some other bees, these stripes are never yellow or red. They will follow the color of the bee’s skin—shiny, metallic, and black, blue, or even green.

Mason Bee Behavior

Mason bees are solitary bees, which means they don’t live in colonies. This, of course, means that they don’t have workers or queens either. Female mason bees are responsible for building their own nests, scouting and foraging for their own food, and defending themselves.

Mason bees hibernate in winter and emerge in spring. Males are the first to surface, and once they do, they wait patiently for the females to follow so that they can mate. During this time the drones will hang around the nest, searching for signs of emerging females. They can be territorial at this time and may fight with each other.

They waste no time when the females come out. Mating occurs almost immediately. True to bees, the males will not live much longer. The females will move on to build their own nests where they can lay their eggs.

Male mason bees only live for about two weeks after they emerge. Females make it to six weeks. There is generally only one generation of mason bees up and running at a time.

Since they have such fleeting life spans, they are extremely active and work almost a hundred times harder than an entire colony of honeybees will. This makes them excellent and valuable pollinators.

This is emphasized by the fact that mason bees don’t produce honey, and focus more on collecting pollen for their brood than nectar. When a mason bee forages, they roll in pollen to collect as much as possible. They don’t have pollen baskets, so they have to rely on the pollen sticking to their fur.

As they visit each flower, they will drop some on the way and this is an effective method of cross-pollination. They’re some of the busiest bees you can find, visiting almost 2,000 flowers in one single day.

Mason bees are not aggressive. The females can sting but it’s unlikely that they’ll attack humans. They use their stingers as a desperate means of defense. You would have to personally interfere with a mason bee (by practically squeezing it) before one will harm you. As with other bees, the drones don’t have stingers.

Even if a mason bee does sting you (and shame on you for threatening it!) their stings are mild. So much so, that when measuring pain, mason bees usually don’t factor in at all. Mason bees are a fantastic alternative to honeybees if you’re allergic, but still want to be a beekeeper.

Mason Bee Nests

Perhaps the most interesting aspect of mason bees is their nesting habits. The biggest reason why they forage so hard is to maintain their nests. Remember, they don’t have much time to get their lives in order, so these bees have to push to get everything done in time.

After mating, the females immediately get to work. They collect as much nectar and pollen as they possibly can before they lay their eggs. When they have sufficient resources to set up their homes, they will search for a nesting site.

Mason bees are cavity-nesting bees. This means that they build their nests in existing holes, cracks, crevices, tunnels or other gaps in walls, hollows, and even empty snail shells. They might even settle in abandoned tunnels created by other insects or animals.

As mentioned, mason bees don’t live in colonies but they do prefer to nest within close proximity of each other. It’s common for mason bees to nest next door to one another, or to have parallel nests.

When a female settles into a suitable nesting site, she begins to layer her home. She starts by regurgitating the nectar she has stored. Once her nectar has been laid down, she will deposit the pollen she has collected. She’ll repeat this process, alternating between nectar and pollen as many as 25 times for one single egg. This calls for many foraging trips in between.

Once she’s satisfied with what she’s built, she will lay an egg on top of her nectar-pollen mound. She’ll then cap this cell with mud (again, why they’re called mason bees). She’ll use whatever mud she can find, or whichever type is abundant close by. Mason bees use their horns to pack mud. They carry it back to their nests in little balls.

A mason bee will lay her female eggs at the back of the nest, and her males toward the front. This is the reason why the males emerge first. On average, up to ten cells are created per nest, using mud to partition each one.

The female will then move on to build more nests and will build around five nests each season. She can lay up to 35 eggs in her lifetime.

Why You Should Keep Mason Bees

Some people forget that beekeepers don’t have to manage honey bee colonies. We lean toward honeybees for a number of reasons: they’re the most common to acquire, they’re the standard in beekeeping so equipment is abundant, and they produce honey that we can harvest. Beekeepers might try their hand with other bees though, for observation, education, or even conservation.

If you want to manage mason bees, remember that they won’t give you honey to harvest. Most people choose to keep mason bees because caring for them is almost effortless and it helps with conservation. Since they are so unlikely to sting, they’re also child and pet-friendly.

The most important reason to consider keeping mason bees is their impact on the environment. Since they are such proficient pollinators, we have to make an effort to keep their numbers up. They’re responsible for a lot of our food, and the least we can do is be kind to them.

Caring for Mason Bees

You don’t have to worry about some other problems that plague honeybees, like colony collapse disorder, or even the spread of disease. Mason bees are hardy little insects, and apart from basic maintenance, they require almost no effort at all.

Another significant reason that so many people prefer mason bees is that you can have a home for them almost anywhere. You don’t need to commit your entire yard to them. A mason bee house (or block) is an inexpensive investment that takes up very little space. When you purchase one, make sure that you’ll be able to open it to clean it. This helps with disease prevention.

So long as your garden or the environment the house is in has easy access to flowers, you can take care of mason bees. Remember that they prefer native flowers. Mason bees won’t forage further than 300 feet from their nest. Keep your flowers within range.

Having mud around will make it easier for the bees too.

Be sure that it’s clay soil. If your garden doesn’t have clay soil, you can compensate for this by buying some at your nursery or garden center. Leave some of it in a mound or on a tray, and do your best to keep it damp. If your soil is too dry or sandy, it will crumble and your mason bees will not be able to work with it.

Don’t use pesticides, poisons, or herbicides in your garden as this could kill the bees.

Another thing to consider is that your bees will need water too. If you have a water source in your garden, try your best to place your bee house as close to it as possible. If not, as with the clay, you can compensate by setting some out for your bees. Make sure that it’s clean, fresh water.

You also want to make sure that your mason bee house is hung out of reach of interference. Although your bees won’t sting your children or pets, they could be interfered with. You don’t want to risk damaging your bee house or hurting your bees. Storing your bee house away from the ground also protects the bees from predators.

Keep in mind that mason bees usually nest in shaded areas, so keep them away from harsh sunlight, rain, or other weather conditions. Although they’re more accepting of the cold than other bees, you still don’t want to expose them to nature too much. Keep them somewhere dry and cool.

It’s best to place your bee house facing southeast. This gives them optimal sunshine on spring mornings but guards them against it in the afternoon. Mason bees cannot regulate their own temperatures, and you don’t want them to overheat.

In winter, however, they need the cold. You can take the cocoons and refrigerate them until they are ready to hatch. Just make sure that they’re placed close to a humidifier and that they’ll stay dry. You can also leave them in your garage.

Even if you haven’t decided to keep mason bees, you can still care for them. If you discover a mason bee nest in your garden or around your home, it’s best to leave it there. They pose no threat to you so long as you leave them alone.

If you want to attract mason bees to your home, you can do so with your garden. Fill it with flowering plants. Mason bees aren’t too discerning in the flowers they forage. Most plants that are in season when mason bees are active will suffice.

Otherwise, if you want to try your hand at beekeeping or managing masons, contact your local beekeeper. They’ll be able to help you, and you might even be able to order bees directly from them.


Mason bees are often disregarded, but keeping them is effortless and important. If you don’t have the time, equipment, or space to keep honeybee hives, mason bee houses are a great alternative, and they’re extremely easy to maintain. This also stands true for those with allergies; mason bees are typically harmless.

They’re some of the world’s best pollinators, and you can help them help us by taking care of them. Even if you’re not a beekeeper, you can help. Living in harmony with them is so easy.

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