Mason Bees (Life Cycle + Pics)

Written On: by Theo The Beekeeper

So spring has sprung, and the buzzing of insects seems to fill the air with their busy back and forth motions as they shed the cold winter months that they survived. Flowers are blooming, and the sun radiates its warmth over your gardens as you notice a little creature emerging from cracks, stumps, and wood stocks.

Mason Bees are solitary bees that derived their name due to how they build their nests and the material they use to construct them with. Docile bees, a bit smaller than the honey bee, are blue-black in color and are part of the Osmia genus, of which there are about 300 species.

These little creatures are a delight to have in gardens and orchards as they are fantastic little pollinators. It’s one of the first bee species you will see dancing about from blossom to blossom as spring bursts into action. Although sometimes misunderstood, these bees have some really important reasons to be buzzing around your garden.

Mason Bees

mason bee on flower
Mason Carpenter bee (Hymenoptera, Apidae) nestled into yellow flower collecting pollen and nectar along hiking trails to Doughnut Falls in Big Cottonwood Canyon, in the Wasatch front Rocky Mountains, Utah, Western USA.

So you noticed some activity around your house or in a small dead log that lays in your garden. Well, it’s probably mason bees emerging from their pupae stage and ready to tackle the world.

Mason Bee Characteristics
HabitatMeadows, forests, shrublands Widespread in North America
Life cycleFemales can live 4 to 6 weeks, die after laying eggsMales live  between 1 and 2 weeks but die after mating with females
FoodEats nectar and collects pollen, flowers, fruit trees, and nut trees
Activity periodEarly spring to end summer (March-June)
Size of female10-11 mm in length
Size of male9-10 mm in length
Color of femaleBlue-black with a green iridescent luster
Color of maleBronze body with yellow hairs on the body and a cluster of white hairs on the face
WingspanFemales 1 inch, males slightly smaller

What Do Mason Bees Look Like?

Mason bees are slightly smaller in size than honey bees, about 8 to 11mm in size. The females can easily be identified apart from the males, as the females have black bodies with blue or green shimmering luster to them with black abdomen hair to collect pollen.

The male mason bees are smaller than the females and have a bronze body with pale yellow hairs on a sloping abdomen. These are typically the first bees you find on your flowers as they search for pollen to nourish them until the females hatch.

Why Are They Named Mason Bees?

mason bee on paper
top view of male wild bee, Osmia bicornis or red mason bee isolated on white background.

They are appropriately named for the material these little creatures use to make their nests. The females will find and make their nests in cracks in the wall of your house, take over an empty cavity where insects have bored into the wood, also sometimes found in deadwood or stems and hollowed out reeds, pretty much any tunnel-like cavity that she can call home.

They will use any available material that can be scooped out and accommodate her needs to build a nest for the eggs she will lay.

Another reason why they are called mason bees is because of how the female bees construct individual compartments for the nest using a mortar-like application of mud.

Are Mason Bees Aggressive?

Mason bee, like much of the Osmia genus, is not aggressive. These docile little creatures are the perfect backyard pollinator for anyone.

Female mason bees possess a stinger, but being social and non-aggressive pollinators, they rarely use it unless trapped or squeezed. Their sting is also a lot less painful than that of the honey bee. The male mason bees do not have a stinger at all.

The mason bees do not live in communities in hives or produce honey, so they do not need the stinger to protect against invaders, which means that the protective gear is not necessary when dealing with this pollinator.

Are Mason Bees Solitary?

Mason bee-like most bees in its genus, are solitary. Unlike the social honey bee, these bees do not have a queen and a hive that stores food for the next generation of bees to hatch or the winter food storage to get them through the cold months.

They also do not have a hierarchy order of jobs for which each bee is responsible. The mason bee is very much a loner in the sense that each female mason bee tends to her own nest and brood, but they do live gregariously with their fellow masons, and you may sometimes find them building their nests next to each other if a bee house is available, for example.

Read more...  Bee Life Cycle (Images + Guide)

Male mason bees will hatch with one purpose: to fertilize the females when they come out.

Where Do Mason Bees Make Their Nests?

mason bee going to its nest
Osmia wall bee sitting on nesting aid

These are tunneling insects and enjoy making their nests under rocks or in bark crevices or abandoned bored-out holes made from wood boring insects. But making their nests in and around your home is not uncommon.

Cracks of air bubbles in your cement can make a great nesting area for them. They have strong back legs and can easily shovel out any excess debris in the hole to make the nest comfy for what they need it.

To attract more mason bees to your gardens or orchards, you can make your own bee house or buy ready-made wood hotels for them to nest in.

Can Mason Bees Damage Your House?

The short answer is no, but once the nest is empty again, it can be damaged due to environmental conditions.

So the mason bee itself cannot damage your house as they do not boreholes into the walls. They only use a small crevice in the wall to build their nest.

You may notice that they remove debris in the crevice; this is the bee’s way of nesting, making the place her own. She is, in actual fact, only dusting the place out. Mason bees will not bore deeper and enlarge the space.

If they do not find the crevice suitable for nesting, they will move on to the next possibility.

Your walls may get damaged if water gets into the cracks. Once the bees hatch and break out of the wall, the hole in the wall is susceptible to water entering the crevice. This will create damp problems inside the crevice and can cause damage to the wall and house.

What Do Female Mason Bees Build Their Nests With?

After finding the right home to safely lay her eggs, the mother bee starts to collect mud that she carries in her jaw. You may find that the mason bee will dig several inches into the soil to find the perfect consistency of mud she needs.

The best mud for mason bees to construct the nest is soft, damp, and holds a high amount of clay for the perfect consistency that she will need to build each wall between the nests.

Even though the tunnel is closed off and secured at one end, a mason bee will almost always build an inner wall lining inside the nest, or this is used to shut off a part of the crevice that goes too deep, generally longer than 7 inches.

The gathering of mud for this nest section can be long and tiring, with almost a dozen trips to build up enough mud to construct the inner wall.

Once the first wall of her nest is built, the female mason bee will start collecting the food that will sustain the larvae in that cell for its growth.

To provision, one cell may require 15 to 40 trips and includes visiting about 75 different flowers to harvest the pollen and nectar. In good conditions with unlimited resources, she may be able to supply a single cell in a matter of hours.

Once the food has been collected and stored in the cell, she lays an egg and immediately proceeds to gather mud to close off the incubation room for her larvae. After which, the whole process starts again.

Mason bees lay their eggs with the female gender in the back, meaning the first eggs laid are female. The female gender is determined by fertilizing one of her eggs with the stored sperm from her spermathecal.

Once she has laid all the female eggs, she proceeds to lay the male eggs in the front of the nest. This gender selection is made by laying one egg without using any sperm.

What Is The Life Cycle Of Mason Bees?

The life cycle of mason bees is nothing like that of the honey bee. Mason bees are generational or have one brood yearly. Male mason bees will emerge about three to four days before the females.

Read more...  Stingless Bees

Lifespan Of The Male Mason Bee

Once the females start to emerge, the males will pounce on them, often before the females even have a chance to fly off and try to fertilize them.

If the female mason bee is ready to mate, she will raise her abdomen, retract her stinger, and begin mating. Sperm is stored in the female’s spermathecal tubes while her ovaries mature.

Male mason bees die soon after the mating process.

Lifespan Of The Female Mason Bee

Female mason bees will be ready to lay eggs about one to two days after the mating process is complete. During this time, she will collect food and find suitable nesting areas for her brood. Some mason bees will prefer to nest near where they emerged from.

After the female has located and orientated herself with her new home, she begins the process of laying her eggs and constructing the nests. Under favorable conditions, a female mason bee will live up to one month. She can construct 1-6 nests and lay 5-15 eggs per nest during this time.

Lifespan Of The Pupae

Once the female mason has laid her eggs, the growth of the larvae will depend partly on the temperatures. Under normal spring conditions, the laid eggs take one week to hatch.

As the egg hatches, the larvae feed for about another week on the egg yolk, after which it will start to shed and grow into a larger grub, at which point it will start to feed on the provisions the mother has left for them in their solitary cell.

Larvae of mason bees go through five different stages of growth. In the final stages of the larvae growth, it will finish the last of the food reserve before spinning a cocoon around itself, resting for most of the summer. As summer slowly comes to an end, the larvae inside shed again and transform into a pupa.

This first stage of the pupae resembles the form of a bee but is totally white. After a month, the pupae will shed again and transform into an adult bee but remain dormant through the winter months.

Exposure to cold temperatures is necessary for the final stage when the bee emerges as the winter starts to dissipate.

Males are the first to emerge, about three or four days before the females, after which the cycle repeats itself again.

LarvaeStage 1-egg is laidStage 2-egg hatch, the larva feeds on the egg yolkStage 3-feeds on the provision of food in the cellStage 4-continues to feed and growStage 5-larvae finish food and spins a cocoon.Hatches after about a weekApprox. 1 week2 weeksApprox. 2 weeks2 weeksMid MayEnd  MayBeginning JuneMid-JuneEnd June
PupaeStage 1-Pupae develops and looks like a bee but is pure whiteStage 2-Pupae develops into a dormant adult bee1 month 6 monthsJuly August
MaleEmerges as the first bees after winterLives a few weeksApril
FemaleEmerges a few days after the malesLifespan of about 1 monthApril

What Are Mason Bees Good For?

Mason bees are great pollinators, especially for the early flowering trees and orchard plantations, as they are the first bees to emerge in early spring as soon as the winter fades. Once the temperatures reach 55°F, they start to hatch and immediately start to forage for food.

How Do You Attract Mason Bees?

When attracting mason bees to your surroundings, it is very important to consider the following to ensure your mason bees are safe, fed, and protected.

1. Housing Possibilities For Nests

They are easy-going and are not over fussy about their accommodation. You can easily attract mason bees to your garden by buying or making your own bee house for them to nest in.

Make your own nest by drilling holes into any untreated wooden blocks, except for cedarwood, as this wood naturally repels insects. Make the holes about 5/16″ in diameter and at least 6″ deep, with only one opening.

You can also make a mason bee house by placing paper straws in a container and hanging it close to a food source.

If you don’t have time or the creativity to make your own, there are plenty of options to buy ready-made mason bee nesting houses.

Read more...  Female Bee (Types + Images)

Any mason bee nest should be placed between four and seven feet from the ground.

2. Location, Location, Location

In nature, mason bees will have an internal instinct of where the safest and most ideal location to place their nests. If you are creating a housing possibility to attract mason bees, then finding the right spot is very important to ensure that mason bees actually move into the house.

Making sure the nest is situated away from where water can reach it and is protected in some way from elements and predators is a great start.

Making sure that the nests get some sunlight is important. Morning sunlight is ideal. Try to place the nest in a somewhat protected position from strong winds and will not be directly affected by the winter cold.

3. Proper Food Sources

Mason bees forage the nectar and pollen of nearby plants from their nest. They prefer the single petal variety of flowers as it is much easier for them to collect the pollen on their abdomen hairs.

Some fantastic flowers well suited to the mason bees are but are not exclusive to the Back-Eyed-Susan, Aster flowers, Poppies, and Alyssums. Blossoming fruit trees such as apple trees, peach trees, apricot trees, and pear trees are also a great nectar source for the mason bees.

Planting various flowers allows the mason bee to have diversity in its food source. They are also attracted to brightly colored blue, purple, and yellow flowers but also tend to visit white blossoms.

4. A Good Mud Source For The Building Of Nests

A good mud source is important for mason bees to ensure the walls they build in the nest are strong and don’t crumble. So, finding soil with a high concentration of clay is ideal for the mason bee.

If you do not have this soil mix near your mason bee house, you can always buy some online and from retail beekeeper suppliers.

Place the mud source near the bee house, about fifty feet, and follow the product’s instructions. Remember always to keep the soil moist.

5. The Presence Of Pests, Diseases, And Predators

Mason bees are prone to a multitude of pests and parasites. These come in what we can describe as two categories,

  • the all-year-round pests and parasites
  • the seasonal pests and parasites

Unfortunately, these docile little creatures are not excluded from the pestering of some pests and predators, so you must ensure the houses are well looked after and protected.

One of the predators that cause damage to mason bees is the birds, so putting a small hole mesh around the bee house is a good start to prevent the birds from feasting on your mason bees.

Mason bees are highly susceptible to pesticides, so be careful when applying any pesticide to your lawn or garden so that the flowers and food sources do not contaminate the pesticides. Try using all-natural ingredients for a pesticide if you need to spray veggie patches or flowers.

All these factors are important to ensure the bees’ survival, and that they remain in the environment, you envisioned them for.

What Do Mason Bees Eat?

Mason bees feed on nectar to sustain their daily activities. They also use this nectar by regurgitating the substance into the cell and adding pollen to create a food source for their offspring.

As mason bees are active from early spring through to late summer, it is important to provide them with a range of flowers that bloom during these periods.

Ensuring that the flowers are near their bee house is vital as the mason bees forage within 300 yards of their nests.

What Flowers Attract Mason Bees?

As we previously mentioned, the flowers with single layers of petals are the preferred blooms for the mason bees but trying to keep the more native flowers to feed these bees.

Here is a short guide on what flowers attract mason bees, when they bloom, and what hardiness zones you can expect to find them.

Flower ideas for your mason bees.

NameColorBlossom seasonHardiness Zones
Asterwhite, blue, purple, pinklate summer, early fall5, 6, 7, 8, 9
Poppieswhite, purple, red, orangelate spring, early summer2, 3, 4, 5, 6, 7, 8, 9, 10, 11
Black-eyed Susanred, orange, yellowsummer3, 4, 5, 6, 7, 8, 9, 10, 11
Alyssumpurple, white, pinkspring, summer9, 10, 11
Lavenderpurple, bluespring, summer5, 6, 7, 8, 9, 10
Wildflowersan array of colorsspring, summer, fallCheck to see what wildflowers grown in your zone
Crocuspurplefall3, 4, 5, 6, 7, 8
Salviablue, purplesummer, fall3, 4, 5, 6, 7, 8, 9, 10
Sunfloweryellowsummer, fall5, 6, 7, 8, 9
Butterfly bushred, pink, whitesummer5, 6, 7, 8, 9, 10
Catmintbluesummer5, 6, 7, 8, 9
Common Heliotropeblue, purple, whitesummer, fall11
Pear blossomswhitespring5, 6, 7
Daisieswhite, pink, yellowspring, summer, fall5, 6, 7, 8, 9


So to sum everything up, mason bees are docile solitary bees that tend to their own brood. They do not form part of a colony and hive system. These busy bees are generational and only live for a short, roughly two to six weeks.

Although they do not produce honey like the normal honey bee, they do eat nectar and collect pollen to feed their pupae. As one of the first bees to emerge after the cold winter, they are fantastic pollinators of early blooms, fruit trees, and nut trees.

More and more people are trying to attract these bees to their gardens and orchard as they are much easier to manage because they do not sting. So if you want to hear the buzzing of spring, help attract some mason bees by placing bee hotels in your garden.



Theo The Beekeeper

When I was a kid, my dad used to keep bees around the small farm we had, and I absolutely loved helping him. In the past few years, we’ve picked up the hobby again, and I’ve been doing a lot more research. This website is the accumulation of things I’ve learned along the way! You can learn more about my journey and the resources I’ve developed on my about page.

Leave a Comment