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Science & Nature • Insects

Mason bee

Mason bee is a common name for bees in the genus Osmia, a group of solitary bees in the family Megachilidae.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 27, 2026|2 min read| Fact-checked

Mason bee is a common name for bees in the genus Osmia, a group of solitary bees in the family Megachilidae. They are named for their use of mud to partition and seal nest cells in cavities such as hollow stems, beetle holes, and other small openings. Many species are important early-spring pollinators, especially for fruit trees and other orchard crops.

Description

Mason bees are small to medium-sized solitary bees in the genus Osmia. They are found mainly in temperate parts of the Northern Hemisphere and are known for carrying pollen on the underside of the abdomen rather than on the hind legs like honey bees.

Nesting behaviour

Females build nests in narrow cavities such as hollow stems, beetle tunnels, and holes in wood or masonry. They use mud to separate and seal individual brood cells, which is the source of the common name.

Pollination

Mason bees are valued for pollinating fruit trees and other early-blooming plants. Sources describe them as highly efficient pollinators, and some species are managed for orchard use.

Life cycle and seasonality

Many mason bees emerge in early spring, when temperatures begin to rise, and use available blossoms for pollen and nectar. Their short active season makes them especially useful for early fruit bloom.

Key facts

  • Mason bees are solitary bees in the genus Osmia, with more than 350 described species.
  • They use mud to build and seal nest cells, giving them the name "mason" bee.
  • They do not produce honey or beeswax.
  • They are effective pollinators of fruit trees such as apples and cherries.
  • They are generally non-aggressive and sting only if provoked.
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Canadian context

Mason bees are relevant to Canadian gardeners and orchard growers because they are native or naturalized in parts of North America and are widely used as efficient pollinators for fruit trees in temperate regions, including Canada.

Frequently asked questions

What is a mason bee?
A mason bee is a solitary bee in the genus Osmia, known for using mud to build and seal its nest cells in cavities.
Do mason bees live in hives like honey bees?
No. Mason bees are solitary and do not form the large social colonies typical of honey bees.
Why are they called mason bees?
They are called mason bees because they use mud in a masonry-like way to construct and partition their nests.
Do mason bees make honey?
No. Mason bees do not produce honey or beeswax.
Are mason bees good pollinators?
Yes. They are especially effective pollinators of fruit trees such as apples, cherries, and pears.
Do mason bees sting?
They are generally non-aggressive and sting only if provoked or threatened.

References

  1. Britannicahttps://www.britannica.com/animal/mason-bee
    Supports: Genus Osmia, solitary nature, mud nesting, lack of honey production, general sting behaviour.
  2. Chesapeake Bay Programhttps://www.chesapeakebay.net/discover/field-guide/entry/mason-bee
    Supports: Size, pollen-carrying method, and importance for pollinating fruit trees.
  3. National Institute of Environmental Health Scienceshttps://www.niehs.nih.gov/health/kids/topics/natural-world/wildlife/insects/mason-bees
    Supports: Solitary behaviour, nesting in pre-existing cavities, no honey or beeswax, and early spring pollination role.
  4. U.S. Forest Servicehttps://www.fs.usda.gov/wildflowers/pollinators/pollinator-of-the-month/mason_bees.shtml
    Supports: Orchard bee name, fruit-tree pollination, and managed use in agriculture.
  5. Oregon State University Extension Servicehttps://extension.oregonstate.edu/catalog/pub/em-9130-nurturing-mason-bees-your-backyard-western-oregon
    Supports: General name, mud-based nest construction, pre-existing holes, pollination efficiency, and orchard value.
  6. The Wildlife Trustshttps://www.wildlifetrusts.org/wildlife-explorer/invertebrates/bees-and-wasps/red-mason-bee
    Supports: Solitary nesting behaviour, mud-lined cells, seasonal activity, and non-aggressive nature of a mason bee species.