If you’re planting backyard fruit trees or small orchard, you may have heard that mason bees can help with pollination. Here are 4 simple steps that can help you attract mason bees to your fruit trees. Step 4 includes directions for making your own mason bee house.
What is a Mason Bee?
From the genus Osmia, of the family Megachilidae, mason bee is a general term for any bee that collects organic material from the environment to make their nest. Here are a few things to know about them:
- They are black or metallic blue-green.
- Mason bees range in size but are typically about half the size of a honey bee.
- They don’t sting, so they’re an uncomplicated beneficial insect to invite into the garden. (Well, the males don’t sting and the females rarely do and only under extreme duress.)
- They’re efficient pollinators in the garden and orchard, even considered to be more efficient than honey bees.
—>>>Please visit this article from Backyard Beekeeping to learn about the life cycle of a mason bee.<<<—
This is important to understand because it will effect the timing of when you place your mason bee houses outside in the spring and when you take them in for the winter.
What Does a Mason Bee Eat?
Mason bees eat pollen and nectar, just like other bees. If you want to attract mason bees to your garden and orchard, it’s important to provide them a lot of flowering plants in the early and mid spring when they are most active. The more flowering plants you have in the spring, the less competition for food there will be from other pollinators for the mason bees.
You’ll have earlier flowering fruit tree varieties like apples and cherries that bloom as soon as your weather and soil begin to warm. If you’d like to attract mason bees to your fruit trees as soon as they’re able to fly, you can put other flowering plants around them as a lure.
- Quince bushes
- Alpine Strawberries
- Any spring blooming plant native to your area*
*Native plants can be observed in fields, meadows and even ditches. Once you identify them, you can grow them from seed in your own garden. There are online and local plant growers who sell native wildflowers and grasses.
—>>>To learn more about how to plant for pollinators, I suggest you read The Bee Friendly Garden, by Frey and LeBuhn. This book has lists of plants to consider for the garden, including when they bloom and where to plant them.
We discuss this book along with other bee-friendly things you can do in your yard in our Bee Friendly Garden article here. <<<—
You might also consider these —>>>Ground Cover Plants for Pollinators<<<—
Attract Mason Bees to Pollinate Because…
Here are some pollination benefits and reasons to attract mason bees to your orchard.
Mason bees are much more willing to pollinate fruit trees in the cool temperatures of early spring than honey bees. Honey bee prefer to stay in their warm hives until the weathers warms up a bit, but mason bees are less fussy about temperature and begin to emerge from their nests once temperatures begin to hit 55F/13C. This means that mason bees can be pollinating your early blooming fruit trees and finish their work for the season as other pollinators are starting to wake up for the year.
Quick and Efficient
Mason bees are quicker and more efficient at pollinating than even honey bees! They move quicker from flower to flower but they also carry the pollen in a way that pollinates efficiently. Honey bees tuck their collected pollen into bags on their legs after mixing it with nectar to wet it down. They end up with pollen on their heads and other places and end up moving pollen around that way. However, mason bees absolutely cover themselves in loose pollen and drop it everywhere as they travel from bloom to bloom. This results in high levels of pollination compared to other insects.
Mason bees are a lot less work than honey bees since they don’t produce honey, so you don’t need to feel compelled to harvest it. Additionally, mason bees will forage pollen in orchard trees like pears that have less sugar (nectar). Honey bees are more interested in high sugar plants because they have all that honey to make. Mason bees, on the other hand, don’t make honey and are willing to slip into any fruit tree bloom you have and pollinate it.
Mason bees nest in reeds, logs and even snail shells if they have to! You can provide them with simple nesting sites (as described in detail below) but you don’t have to provide or maintain hive boxes like you do with honey bees.
How to Attract Mason Bees to Your Fruit Trees
Here are 4 steps to attract mason bees to your fruit trees
#1 Provide Food
We already talked about providing them with what they need to eat – lots of pollen and some nectar. Make a plan now to inter-plant your fruit trees with other flowering plants. Especially look for native plants that easily grow in your area because wild bees like masons are very attracted to them.
#2 Provide Water
All insects require water just like you and I and mason bees are not exception. Ponds and creeks will do if they are very close. Mason bees will only travel up to 300 feet/100 metres away from their nesting sites, so keep that in mind.
Sometimes a leaky hose bib or a birdbath will be easier for them. You can also build bee-friendly watering dish. There are several pictures online of fancy ones and simple ones – here’s one of each.
- Feathers in the Woods shares a picture of her simple bee waterer in the #5 section of her fine —>>>article on attracting pollinators to your garden <<<—. You could probably make this one right now.
- Chicken Scratch NY shares a slightly fancier one (still very simple) in her —>>>DIY bee and butterfly waterer article here.<<<—
#3 Provide Mud
Mason bees nest in wood most often, using holes created by other insects and birds, or even old nail holes; they don’t drill into wood themselves. Filling the holes with mud to make them safe and snug for laying eggs, mason bees will need a small patch of exposed dirt in your yard if you’d like them to nest successfully in your garden.
Sometimes people worry about them causing damage to their homes by nesting in existing holes and cracks but they really cause no damage while they nest.
The bees can forage mud, of course, but providing it for them means they have more time to pollinate your fruit trees. A little patch of mud or clay next to the water source will be sufficient for their needs.
#4 Provide a Mason Bee House
If you’d like mason bees to be present in your garden in the largest numbers possible, the best thing to do is provide as many quality nesting sites as you can. You can do this by building a simple mason bee house.
A Few Caveats
Providing mason bee houses doesn’t necessarily increase the numbers of mason bees in your area permanently. Being solitary bees, they have no homing instinct that tells them to return back to a colonized hive, like honey bees. This can make them flighty guests in your garden, since they don’t necessarily return to nest in the place they were hatched.
Also, if you disturb their nesting site for any reason in spring while they’re working in it, they’ll simply abandon it and pick another one. So, be sure to place their nests in spring and then leave them undisturbed.
One last thing to remember is that all bees are territorial and you may have some conflict between mason bees, other native bees and honey bees. I find the best solution to this is variety and spacing. Have one or two mason bee houses per ten trees and
However, with proper maintenance, there isn’t sufficient evidence to suggest that providing mason bee houses harms mason bee populations in any way and doing so can increase the population the first and even second (since not all mason bees hatch the first year) years after you place the houses in your garden. It’s important that you remove or thoroughly clean your mason bee houses every two years to avoid pathogen build up and even mold (especially if you live in a humid area).
Where to Put a Mason Bee House
Hang your mason bee house in a very sunny, southeast facing position, protected from wind as much as possible. If your springs and summers are hot, be sure to provide afternoon shade.
Also, place the mason bee house 3-5 feet off the ground to avoid splash up from the ground when it rains. Be sure to provide some kind of roof, too, to prevent water from getting into the nesting site and causing mold.
(The mason bee house pictured here is under the cover of a porch roof so this one doesn’t have its own covering. The ones we’ve set out on the fence do.)
You will likely want to cover your mason bee house with hardware cloth to protect the larvae from birds. Most birds won’t be able to reach the larvae if you’ve drilled deep enough (at last 5”-6” for best results) but flickers, especially, can be pretty determined. And woodpeckers have very long tongues.
Make Your Own Mason Bee House
There are really two kinds of wooden block mason bee houses. With either design, you will need to place your mason bee house in the orchard in the early spring as mason bees emerge from their winter nests. Then, if you live where the winters get to freezing or below, you will need to bring the mason bee larvae into a garage or root cellar to protect the babies from freezing. The following spring, you will place the larvae back outside to hatch.
With either design, you will need to place your mason bee house in the orchard in the early spring as mason bees emerge from their winter nests. Then, if you live where the winters get to freezing or below, you will need to bring the mason bee larvae into a garage or root cellar to protect the babies from freezing. The following spring, you will place the larvae back outside to hatch.
More details and specifics on that below, but mason bee houses are not like beehives that stay out all year long. You should know that upfront!
Design #1 House with Trays
The first design, which is nicely detailed in the very fine book Pollination with Mason Bees by Dr. Margriet Dogterom, is really two trays with channels cut out with a table saw for the bees to nest in. One tray is inverted and stacked onto the other so that the channels line up, creating a cozy corridor in which baby mason bees can develop. As Dr. Dogterom points out,
“The biggest advantage of trays is that they can be dismantled and examined….The tray system allows for the removal of predators, and parasites and increases your bee population, higher than is normally observed in nature.”
If you don’t have a table saw, you can make the following block mason bee house with only a drill.
Design #2 Block House
Using the 6-8” block of wood, we drilled holes six inches down inside the block. To make your own mason be drilled-hole house, you can really use any untreated block of wood (except perhaps cedar which naturally repels insects) and a 5/16” drill bit (that seems to be the size hole that mason bees favor most).
You can use a template to evenly space the holes you’ll drill into the wood, if you’d like, but the mason bees really don’t care either way.
- Block of untreated wood 6-8” long – we used a 4 x 4 block
- Drill bit, 5/16”
- Water resistant paper, optional
- Scrap wood for roof structure or a larger container to insert the bee house into to protect from weather
- Hardware cloth to fit over the entrance of your mason bee house, staple gun to affix
- L brackets or pipe strap to affix the house to a post or fence
- Use a drill press with a 5/16ths bit and drill initial holes up the length of your drill bit, just as deep as it will go. This will get you started with the holes and make it easier to get uniform coverage and make it easier for you to use your cordless drill to finish off the job. If you don’t have a drill press, you can use a cordless drill to drill all the holes. The drill press just enables you to set up completely straight holes. With a cordless drill, you run the risk of going even slightly sideways and possibly drilling into another bee tunnel. If you don’t have a drill press, don’t sweat it and just keep your holes farther apart to avoid crossing them over by accident. Either way, put no more than 25 holes in any one house (to avoid confusing the bees), staggered around the block or using a template.
- If you can, angle the drill so that the holes tip slightly down to allow for water drainage should water get inside. This isn’t 100% necessary if you provide a cover for the mason bee house. However, it can help keep the mason bee house mold free.
- Use the cordless drill with 5/16ths paddle bit finish off holes so that they’re at least six inches deep (longer is ok, too). Use a piece of electrical tape on the drill bit to mark how deep you want to go into the block; this will ensure that you don’t go too deep and bust through the back. (If you do drill to the back, that’s fine, just be sure to add a back piece so the bees are protected.) The male bees are laid at the front and the females are laid at the back. Drilling deep nesting tubes protects the larvae from birds and the elements, making it more likely that the boys make it out alive to mate with the girls in the spring.
- After you’re done drilling, carefully bang out any leftover sawdust.
Using Paper Tubes for Mason Bee Larvae?
- Use paper tubes if you’ve purchased or made them. Why use paper tubes? Paper straws inserted into your holes can be removed to more easily sanitize your bee house. If you chose to do this, plan to carefully remove your tubes in the fall, placing the enclosed larvae in a safe place such as a lidded bucket with a single hole drilled into it. When they hatch, the bees will exit through the hole. You can insert new straws into your mason bee house in the late winter/early spring and begin the process over again with clean tubes. In humid areas, this may not be effective as mold can develop on the tubes, requiring that you not reuse the house.*
- Please visit this link from Honey Bee Suite learn more about paper straws for mason bee houses.
*Put Them Out/Bring Them In
If you didn’t read the article linked above about the life cycle of a mason bee, I suggest you do it now. Along with that, here are some things to know about mason bees throughout the year:
- Mason bee larvae can’t be allowed to freeze in your mason bee house.
- If you live where winters get to or below freezing, you will need to bring the larvae inside to a garage or root cellar to keep them safe.
- Place either the tubes filled with larvae or the entire mason bee house full of larvae in a lidded bucket or box with a hole drilled into the side.
- Keep this bucket or box safe and undisturbed through the winter.
- Once spring has warmed past freezing temperatures, put the bucket or box in the orchard so the mason bees can emerge from it in the spring and into your orchard.
- If you have new mason bee houses near their hatching site among your fruit trees, new mason bees will nest in the new houses. This is a beautiful cycle that can repeat year after year.
Finishing Up the Mason Bee House
- Paint or draw a design near the entrance of at least half of the holes to help the bees orient to their correct holes. The less time mason bees spend trying to “remember where they parked”, the more time they can spend pollinating. Dr. Dogterom explains,
“Decorating the front of the nest makes it easier for bees to find their own nesting tunnel. A nest can be decorated with simple designs and or with one or two colours. Too few or too many markers at the nest will confuse the bees. Bees that are confused by the markers or lack of markers close to their nest can be observed flying in and out of several nesting tunnels or getting thrown out of neighbors’ nesting tunnels.”
Dr. Dogterom suggests using yellow, mauve, pink and blue colors but not to make them too fancy or complex. Simple letter shapes like X, V or O will do nicely.
- Use a staple gun to attach a hardware cloth protective cover. Fit the hardware cloth over the front of the mason bee house, slightly curved outward about an inch off the surface to prevent long-beaked birds from eating your precious mason bee larvae.
- Hang on a post or fence near your fruit trees with your favorite bracket. We used a pipe strap to avoid puncturing the bee house further. Be sure to place your mason bee houses out by early spring when the masons are emerging from their winter nests. If you’ve overwintered** mason bee larvae, be sure to put them out near the orchard to pollinate your fruit trees.
Cleaning Mason Bee Houses
**As was mentioned in step three, it’s important to keep your drilled-house clean. If you use the straws, follow the instructions in step three. If you don’t, plan to put your whole mason bee house into a lidded bucket or box in the fall with a single hole drilled into it so the bees can escape when they’re hatched. Dr. Dogterom suggests making sure that the box is painted dark because the bees will be less likely to return to it if it’s not brightly lit. After the bees have hatched (which can sometimes take two years to get them all), you can just burn the wood.
The biggest drawback to this block wood mason bee house design is that you really can’t clean them. However, the bees do seem to like them and use them well. We have an abundance of wood where we live, so burning them after two years is an acceptable outcome for me. Plus, these mason bee houses make a wonderful family project. Watching the bees set up during the year and emerge in the spring is truly a joy.
Where to Find Mason Bees
You can purchase mason bees online, however the survival/hatch rate can be unpredictable. The best mason bees for your area are the variety that are native to your area. If possible, try to find a mason bee seller close to you – in your state or at least in your area of the country.
You can also provide a variety of mason bee houses and see how many native bees you can attract. This is usually what I do. I figure, if I build it, they will come – and they usually do. I’m not very scientific about my mason bees simply because my area is blessed with so many and I know they’ll show up if I provide good housing.
If you struggle to identify mason bees in your yard and aren’t sure of their native numbers, go ahead and purchase larvae and see how it goes. Make observations, take notes and do a little better each year.
More Mason Bee Resources
If you’d like to learn more about mason bees, here are a few links.