Mason Bee: All You Need to Know for a Thriving Garden

Mason bees are fascinating pollinators that play a crucial role in our ecosystem. These little insects are native to the Western US and Canada and are known for their early emergence in the spring, even before honeybees. Efficient pollinators, mason bees are particularly effective at transferring more pollen and visiting more types of flowers, which makes them valuable contributors to our landscapes and food sources link.

These hardworking bees are often mistaken for their honeybee counterparts, but a closer look reveals key differences. Mason bees, for example, sport a unique dark metallic blue coloring, which sets them apart from the striped brown appearance of honeybees bonus. One distinctive characteristic is their nesting habits: while honeybees live in large colonies, mason bees are solitary, making individual nests out of mud and other materials link.

Mason Bee Fundamentals

Physical Characteristics

  • Size: Mason bees are usually between 1/4 to 3/8 inches in diameter.
  • Color: Blue Orchard Mason Bees are dark metallic blue, while other Osmia species might be brown or black.
  • Stripes: Unlike honey bees, they don’t have brown stripes on their body.

Geographical Distribution

  • Location: Mason bees are native to North America, specifically to Western US and Canada.
  • Habitat: They often make their nests in small cavities and holes.

Life Cycle

  • Spring emergence: Male mason bees come out when the temperature reaches mid-50s.
  • Pollination: They help pollinate nearby flowers and plants.
  • Mating: Female mason bees mate immediately after their emergence, and the males die soon after.

Mason Bee Behavior

Solitary Nature

Mason bees are solitary insects, unlike honeybees, that live and work independently. They do not form colonies or have a queen bee. Some examples of solitary bees include:

  • Blue Orchard Mason Bee (Osmia lignaria)
  • Red Mason Bee (Osmia bicornis)

Nesting Habits

Mason bees create nests in tunnels, often within wood cavities, hollow stems, or by using mud materials. Common places where you can find a mason bee’s nest are in a shed, garage, or hanging from a tree.

Pollination and Foraging

Mason bees are valuable pollinators and contribute to the pollination of fruits and flowers. They forage for nectar and pollen, and efficiently pollinate a variety of plants.


  • Enhance fruit tree pollination
  • Improve crop yield
  • Require less maintenance compared to honeybees


  • Limited to pollination of specific plants
  • Short active lifecycle

Reproduction and Offspring

Mason bees reproduce in the spring, with males emerging first, followed by females. Once the female mason bees mate, they lay eggs in their nests, sealing each egg chamber with mud.

Life Cycle:

  1. Eggs are laid in nesting chambers
  2. Larvae feed on stored pollen and nectar
  3. Larvae spin cocoons and pupate
  4. Adult bees hibernate over winter in cocoons

Mason bees are an essential part of the ecosystem and are known for their pollination efficiency. By understanding their behavior, we can better support these essential pollinators in our gardens and surroundings.

Creating a Mason Bee Habitat

Types of Bee Houses and Nesting Materials

Mason bees require a proper habitat to thrive. Some popular choices for bee houses are:

  • Tubes: Use bamboo tubes, cardboard tubes, or natural reeds for nesting sites. These materials are readily available and affordable.
  • Nesting blocks: Create wooden nesting blocks with pre-drilled holes, which mimic natural cavities in tree trunks and branches.

Both options can be easily found online or at gardening supply stores.

Choosing the Right Location

When setting up a mason bee habitat, consider these factors:

  • Place the bee house near gardens, fruit trees, and flowering plants to ensure pollen sources are available.
  • Position the habitat to receive morning sun exposure, as it jump-starts the bees’ activities.
  • The location should be sheltered from harsh winds, rain, and predators.

Selecting Appropriate Plants

To attract and support mason bees, it’s crucial to have specific plants in your backyard:

  • Plant a mix of native plants, fruit trees, and flowering plants to offer pollen throughout the season.
  • Examples of recommended plants: willow, lupine, and apple trees.

Having a variety of plants benefits not only mason bees but other pollinators in your garden.

Proper Temperature and Environment

Mason bees are cold-hardy and can tolerate low temperatures better than honeybees. However, they still need a suitable environment:

  • Temperatures should be between 54-77°F (12-25°C) during the active season.
  • Along with plants, provide a water source nearby for bees to drink and collect mud to seal their nest chambers.
Blue Orchard Mason Bee Honeybee
Cold-hardy Sensitive to cold temperatures
Do not sting Can sting

By following the guidelines provided, you can create a thriving backyard habitat for the blue orchard mason bee, giving an alternative to the more traditional honeybee.

Caring for Mason Bees

Harvesting and Storing Cocoons

Harvesting mason bee cocoons in the fall can protect them from pests and diseases. Gently open nesting sites and remove cocoons, taking care to not damage them. Then, “wash” the cocoons to remove most mites and diseases that may be present ^1^. Store the cleaned cocoons in a ventilated container and place it in a cool, dark area.

  • Cold storage: ideal temperature is between 34-40°F (1-4°C)
  • Humidity control: maintain relative humidity around 60-70%

Preventing Pests and Diseases

Caring for mason bees involves protecting them from parasites, predators, and pathogens ^2^. Some common threats include:

  • Chalcid wasps: pierce cocoons and lay eggs in them
  • Pollen mites: consume the pollen provisions in bee nests
  • Molds and fungi: grow on the mud walls of nests

Preventive measures:

  • Clean nesting sites annually
  • Rotate nesting materials
  • Use a pollen mite powder during cocoon storage ^3^

Rain and Cold Weather Protection

Protect mason bees from rain and cold weather by providing adequate shelter for their nesting sites. Some tips to consider:

  • Position nesting sites under eaves or roof overhangs
  • Install a rain guard or roof to protect nests
  • Face nests towards the morning sun (east or southeast) to provide warmth

Here’s a comparison of mason bees and honey bees:

Feature Mason Bees Honey Bees
Pollination efficiency High Moderate
Nesting habits Mud-filled cavities Waxed hives
Managing difficulty Easy Requires expertise
Temperature sensitivity Cold-tolerant Less tolerant

Remember to provide a variety of flowers for pollen and nectar to ensure the health of your mason bees and provide them with adequate resources ^4^.

The Importance of Mason Bees

Biodiversity and Ecosystem Health

Mason bees are crucial pollinators that help maintain biodiversity and contribute to overall ecosystem health. These solitary bees:

  • Play a significant role in pollination
  • Enhance biodiversity by pollinating native plants
  • Support other wildlife by supplying resources like nectar

In comparison to other bee species, such as the leafcutter bee from Megachilidae family, mason bees are known for their mild temperament and are less likely to sting, making them a more desirable addition to the ecological landscape.

Boosting Crop Yield and Pollination Efforts

Mason bees are efficient orchard pollinators, especially for fruit trees like apples. They:

  • Visit more flowers per day compared to honeybees
  • Have a higher rate of cross-pollination due to their messy pollen collection method

Here’s a comparison table of mason bees and honeybees in terms of pollination efficiency:

Pollinator Flowers Visited per Day Cross-Pollination Rate
Mason Bee 1000-2000 High
Honeybee 300-600 Low

With their pollination efforts, mason bees lead to increased crop yield in orchards and support agricultural operations.

Encouraging Native Plant Species

Mason bees also aid in the propagation of native plants, which in turn provide essential habitat for other wildlife. The Xerces Society and the Ecological Landscape Alliance advocate for the conservation of native pollinators like mason bees, as they assist in:

  • Pollinating native plant species
  • Supporting the growth of hybrid plants

Encouraging a diverse range of native plants not only benefits the ecosystem but also adds visual attractiveness to the landscape.

Mason Bee Identification and Tips

Distinguishing Mason Bees from Other Species

Blue Orchard Mason Bees, also known as Osmia lignaria, are about the same size as honeybees, but with a few external differences. They are dark metallic blue and do not have the striped brown appearance of honeybees. Mason bees have hairs on their abdomen, which help them collect pollen from wildflowers and fruits. Unlike honeybees, they are solitary bees and do not form colonies with a queen. They also differ in their nesting habits, as they inhabit beetle burrows and other small cavities, while honeybees create nests in beehives.

DIY and Raising Mason Bees

Raising mason bees can be a rewarding and educational experience. Here are some tips for getting started:

  • Nesting boxes: Mason bees use nesting boxes, wooden trays, or bee tubes as homes. Ensure they have enough space to lay eggs and store pollen.
  • Shelter: Mason bees need a safe place to live. Place nesting boxes in a sheltered area, away from direct sunlight, wind, and rain.
  • Food sources: Plant wildflowers or fruit trees nearby to provide ample pollen and nectar for your mason bees.

Note: Mason bees are more efficient pollinators than honeybees, making them great additions to any garden or fruit orchard.

Helpful Resources

Reader Emails

Over the years, our website, has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Now is the time to Plant Cosmos in Southern California to attract insects in the spring.


Subject:  Planting Cosmos
Location:  Mount Washington, Los Angeles, California
November 18, 2013
We used to have Cosmos flowers that naturalized in our garden many years ago after an initial planting in around 2001.  The seeds would drop and we would get new plants each year.  One especially wet year, they grew to well over six feet tall.  Cosmos is an excellent plant for attracting pollinating insects.  We even posted photos of a female Leafcutter Bee on our blossoms in 2006.  Alas, for the past two years we have not had any Cosmos come up on its own, and we didn’t make the effort to purchase any new seeds.

Leaf Cutter Bee on Cosmos
Leaf Cutter Bee on Cosmos

Then several weeks ago, we identified a Cuckoo Leafcutter Bee  for Anna in Hawthorne, and she offered to send us some seeds.  They arrived a few days ago and we have been planting Cosmos seeds among the winter vegetables we put in this weekend, beginning with carrots and onions.  We hope to be able to provide you with photos of insects visiting our Cosmos in the near future.  This is a good time to plant Cosmos in Southern California, but this charming annual can be grown throughout North America, and we would strongly suggest Cosmos as an ideal plant for a bug friendly garden.

Cuckoo Leafcutter Bee
Cuckoo Leafcutter Bee


Letter 2 – Mason Bee


Subject: Carpenter bee?
Location: Albuquerque, NM
July 10, 2017 12:48 pm
Hi – This bee was climbing in a hole the size of my pinkie in a wooden overhang. It was painted, but im not sure if the bee created this hole or the prior owner had drilled a hole leaving exposed wood. It was striped and where he was chewing, the wood began to swell. he never went fully in, just around the edge. I filled the hole with caulk and he went away. Thia is in Albuquerque, NM at about 5500 ft elevation in the hills. It was taken in June.
Signature: KJ

Mason Bee

Dear KJ,
This looks to us like a Mason Bee in the family Megachilidae, possibly
Lithurgopsis apicalis which is pictured on BugGuide.  Of the family, BugGuide notes:  “Some are leaf-cutters, nesting in ground, in cavities, wood. Tunnels are bored in wood or in the ground. Cell is provisioned with pollen (and nectar?), an egg laid, and cell is sealed over with circular pieces of leaves, clay or other materials that fit tightly into cavity.”

Mason Bee

Letter 3 – Probably Mason Bee from Tanzania


Subject: Bee or fly identification
Location: Southern Tanzania
December 31, 2016 5:58 pm
Can you please identify this bee/fly?
Signature: Helen

Probably Mason Bee
Probably Mason Bee

Dear Helen,
Because it so resembles the Giant Resin Bee, we thought your Bee (definitely NOT a fly which would only have two wings) might also be a Mason Bee in the genus
Megachile.  We located many similar looking Mason Bees on iSpot including this individual and this individual.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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