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How to Attract Mason Bees

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Did you know that not all bees make honey? And honey bees aren’t the best pollinators? Mason bees on the other hand…. Spring Mason Bees are gentle, plump, dark-colored hole-nesting bees named after their habit of using clayey, mud to build protective walls. Among the first bees to fly in cool, wet spring weather, spring mason bees are perfect for pollinating fruit and nut orchards and berry patches. Keep reading to learn how to attract Mason Bees to your garden. 

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So, what is a Mason Bee?

For starters, mason bees don’t make honey. But they are amazing pollinators, making it possible for plants to set seed and reproduce, for fruit trees and berry canes to increase their yield, and for flower landscapes to burst with color. They are extraordinary pollinators – just 250-300 females can pollinate an entire acre of apples or cherries – and are often touted as being more efficient than honey bees. Of the roughly 150 mason bee types in North America, most are native. Also, many types of mason bees occur naturally over wide geographic regions, so it’s possible you have some buzzing about your backyard already. With a few supplies and some knowledge in hand, you could easily start propagating your own population of these native pollinators.

A Gentle, Tunnel-Nesting Bee

Before luring mason bees into your garden, it’s helpful to understand some basics. They are tunnel-nesting, solitary bees, which means that unlike the social honeybee, every female is a “queen” who lays eggs and raises offspring on her own, without the support of a highly-organized, social colony. They are non-aggressive and rarely sting. These bees lay their eggs inside existing tunnels, such as those left by wood-boring beetles or the hollow stems of pithy plants. Luckily, mason bees also nest in man-made tunnels – if the tunnel meets certain criteria.

Early spring mason bees emerge from hibernation when temperatures reach about 55 degrees (some types of mason bees emerge in late spring or summer under different conditions, but in general they are spring pollinators). After mating and finding an existing tunnel for her nest, the female bee gathers mud in her large jaws and uses it to build a wall at the back of the tunnel – thus the name “mason bee.” Next, she makes dozens of visits to garden flowers to collect pollen and nectar, which she heaps into a golden nugget at the end of the tunnel. This nutritious pollen-nectar mass will be her egg’s first meal when it hatches. Finally, she backs into the tunnel and deposits an egg on top of the food source. Once the egg is laid, the female bee collects more mud and uses it to build a wall that seals off the egg inside its own chamber. She repeats this process until the tunnel is filled with well-provisioned eggs, each tucked inside its own cell partition. Then she closes the tunnel with a mud plug to protect her offspring from predators.

spring pollinator

An Active Spring Pollinator

This pollen-gathering and egg-laying work is done during the early spring months – when spring flowers, bushes, and fruit trees are in bloom. In the US, this typically occurs between February and May, depending on where you live. A mason bee will fill as many nesting tunnels as she can during her roughly 4-week life span – pollinating flowers profusely as she forages for food to supply her nest. Then she dies.

Inside the nesting chambers, eggs begin their transformation to adult bees. They hatch into larvae and consume the pollen-nectar masses. After a rest period, the larva spins a cocoon, and by about September, a fully-formed adult bee lies inside each chamber (if you purchase or make a special observation tray, you can actually watch this process happen). The adult bee now waits through the winter months until the spring air temperature rises to a consistent 55-degree range, at which point it emerges from the tunnel to mate and repeat the egg-laying, pollen-gathering cycle all over again.

Why Attract Mason Bees

  • Grow more food like apples, almonds, pears, plums, blueberries, and strawberries
  • Ensure or improve pollination of flowers and wild places

What Spring Mason Bees Need

  • 8mm sized nesting holes
  • Minimum daytime temp of 55F/13C
  • Springtime open blooms
  • Moist clayey mud for building nest walls
  • A Bee Friendly Garden free of chemicals
mason bee house

How to Attract Mason Bees

During the early spring months, you can try attracting mason bees by providing nesting tunnels, plenty of bee food, and a mud source. Mason bee houses can be bought or made from wood, thick paper straws, or hollow reeds.

Somethings to consider when making or purchasing your mason bee house.

The bee house should provide a little spot for the cocoons to emerge and a roof that is 2-3” longer than the nesting holes. Mason bees prefer holes that are 5/16” in diameter. The tunnels should be six-inch because the mason bee controls the gender of each egg she lays. Female eggs are deposited in the back of the tunnel (tucked away from rummaging woodpecker beaks or other predators) and males in the front. Since mason bees lay more male eggs than females, a 6-inch tunnel produces more female bees, which in turn increases the potential for a bigger bee population the following year. 

If you are building your own house use non treated wood. By using a sharp drill bit, you will ensured the holes are free of splinters (important), and do not drill all the way through to the end (bees won’t use the holes if you do). If you paint the bee house, allow plenty of time, about a month, for the paint to cure because the smell of wet paint may deter the bees. 

A word of cautions in order to keep your bee population safe from debilitating disease and parasite problems, you must retire the wooden nest blocks after a couple years, or use an emergence box, which allows you to clean your block without harming developing larvae. Emergence boxes – along with other DIY nest construction ideas, maintenance, and native bee facts – are explained in the must-read fact sheet Tunnel Nests for Native Bees, distributed by the Xerces Society. 

If making mason bee nest boxes is not your thing, you can purchase a wide variety of types at gardening centers or online through companies like Crown Bees, located in Washington State.

amazing pollinator

Where to Place Your Nest

Regardless of the nest type you choose, be sure to place it in the proper location. Mount it securely on the side of a building, tree or fence where it will receive the warm morning sun (east or south sides are best) and protection from wind and rain. Bees are cold-blooded and mason bees need the warmth of the morning sun fly and dry nesting tunnels to propagate. Placing the nest four to seven feet off the ground provides additional protection from moisture, and it’s a good height for observing your bees. Try to have a clay-like mud source nearby – within about 50 feet, if possible.

It’s important to place your nest within 200-300 feet of pollen-rich, spring-blossoming plants and trees, so the bees need not waste energy or time foraging for food. Also, it’s ideal if nearby plantings offer blossoms during the bee’s entire foraging season, so females can lay eggs to their full potential.

For a list of native plants that attract these native pollinators, check out Spring Flowering Plants for Bees And finally, try to solve your garden pest problems without using pesticides. Many types can be harmful or even lethal to bees.

bee house

Creating a Mud Source

Create a clay-mud source within 50 feet (15 m) of the nest. The mason bees need mud nearby to use it when they divide the chambers of their nest. They’ll need to make many trips back and forth, so provide a mud source close to the nest for them, either by making your own mud source or buying a mud mix.

Unless you have super sandy soil and no access to other types of soil, you can easily make your own mud source.

Dig a shallow hole and line it with plastic. Use a shovel to dig a shallow hole in the ground. The hole doesn’t need to be wider than 1 foot (30 cm), and a depth of about 10–12 inches (25–30 cm) should be perfect. You can also use a shallow metal or plastic tray to hold the mud instead of digging a hole in the ground.

Fill the hole with soil. You don’t have to fill the hole all the way up with soil, but it should be at least four-fifths full. Adding water to the soil will likely cause it to flatten a bit, so don’t worry about adding too much.

You want the soil to be more clay-filled than sandy—sandy soil won’t work well. If you have sandy soil, you can buy more clay-rich soils at a garden store, nursery, or online.

Keep the mud source moist throughout the season. It’s important that the mud source not dry up so that the bees can easily use it. Monitor the mud source to ensure that it’s still wet, either allowing rainfall to keep it moist, or adding water to the soil yourself.

You can fill the hole using a hose, watering can, or simple glass of water, all depending on how big the mud source is. Make the mud a medium-consistency—you don’t want it to be super thick and difficult to move around, but it also shouldn’t be dripping wet. Add additional soil to the mud source as the bees use it, if necessary.

Buy a mason bee mud mix for an easy mud source. If you go online, you can find several different kinds of mud mixes specifically designed for bees. This option is good if you don’t have access to soil, or just want an easy mud fix. Follow the directions on the box, most likely adding the mix to your soil to provide more clay. You’ll need to add water to the soil and mud mix to make it the right consistency.

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Wait and Watch Bees Fly

The best part of raising spring mason bees is watching them come and go from their bee house. The time you spend watching the bees is not considered a chore!

It can take time for bees to return and show signs of nesting. Male bees emerge first and wait nearby for female bees. Female bees need to mate, get to know the area, and come back to claim a nesting hole. Give the bees at least two weeks to get settled.

As your bees emerge, you may see a beige substance that looks like splattered paint. This is the bee’s first elimination of waste (bee poop!).

After mating, the female will claim a nesting hole and use it as a shelter at night and during poor weather. Then she will start building up pollen, laying eggs, and building protective mud walls. Depending on the weather, it can take several days for a small bee to fill and cap a single nesting hole.

Pro Tip: At night, use a flashlight to peek into the nesting holes. Look for bee faces (or bottoms) peering back at you. Female bees at the back of the nesting hole can be hard to see.

mason bee

Remember to BEE patient.

Many first-time mason bee raisers thought that their bees flew away, and are surprised a few days or weeks later by a mud capped end.

Bees are wild creatures and can decide to move on. For reasons unknown, the bees may nest elsewhere. Sometimes moving the bee house a few feet to a warmer or better location vastly improves nesting. If you chose to move the bee house during bee activity, move it at night to help any nesting female bees reorient to their surroundings in the morning. Strive to maintain a bee house location that faces the south or southeast for morning sun.

Protect Your Nest during Cold Winter Months

In the fall, take down your egg-filled nest boxes and store them in a dark, unheated garage or shed during cold winter months. In early spring, prior to the onset of fruit tree blossoms and other spring-blooming flowers, return cocoons to your garden. As the days warm to a 55-degree range, watch for bees streaming in and out of your nests and then for mud-plugged holes, indicating that a new batch of pollinators – and another season with mason bees – is on the way.

Attracting Mason Bees isn’t that hard and when they start to fly around your yard they will be hard at working pollinating your gardens and helping make the most delicious fruits and veggies. Want to know more about bees visit Our Bee Page.

Get Your Kiddos Involved...

We are always looking for ways to get our kids involved in the homestead. Most of the time it starts with a book. Here are some of our favorite BEE books. 

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