Orchard Mason Bees

(Osmia lignaria)

Orchard Mason Bees are gentle beneficial insects that have great potential as a pollinator of apples, cherries, and other tree fruits, besides in our gardens.

They are found throughout most of North America, particularly in wooded areas but often around homes in towns and cities.

Mason bees are solitary- that is it lives and works alone. It does not produce honey but is a great pollinator.

If you have fruit trees these bees may be your solution but are not the bee for a summer garden.

Orchard Mason Bee

How valuable is the Mason Bee?

As pollinators these bees are much better than honey bees. However, their range and life span are both much less than that of the honey bee

A single bee pollinates the flowers of 120 Honeybees.

The one downside to this bee...

It is a seasonal bee and has a short life. By June they may all be gone and
this isn't good for vegetable gardens.

Homeowners sometimes become concerned when they see the Orchard Mason Bee entering cavities under shake siding or investigating nail holes or other cavities in wood during March through early June. These are not destructive insects, since they do not excavate holes in the wood, though they will clean out loose debris.

No controls are recommended for Mason bees, since no damage is done. If you want to prevent the bee from nesting, holes may be filled with caulking.

The Orchard Mason Bee is usually slightly smaller than a honey bee and a shiny dark blue in color. The actual size of the bee depends largely upon the size of the hole in which it grew.

Males are smaller than females, have longer antennae and an additional tuft of light colored hairs on the face.

Females have hairs on the underside of the abdomen, called the "scopa", for carrying pollen.

Orchard Mason Bee Nest box

Nesting Habits:

This is where the name 'Mason Bee' comes from.

The female Mason Bee uses existing holes in wood and hollow plant stems for a nest. She chooses holes slightly larger than her body, usually 1/4 to 3/8 inches in diameter.

The bee first places a mud plug at the bottom of the hole, then brings in 15 to 20 loads of nectar and pollen which she collects from spring flowers, including apples and other fruits.

If you watch the bee closely as she enters the nest, you can see the pollen on the underside of her abdomen. When the female has provided a sufficient supply of food for the larva, she lays an egg and then seals the cell with a thin mud plug.

She then provisions another cell, and continues in this fashion until the hole is nearly full. Finally the bee plasters a thick mud plug at the entrance.

(Some wasps and leaf-cutter bees also build nests in such holes but their nests can be distinguished from the orchard mason bee nests by characteristics of the plug.)

The plug of the mason bee is always rough while the wasp prepares a smooth plug.

Leaf-cutters seal the holes with chewed-up leaves.

The female Orchard Mason Bee lives for about a month and can produce one or two eggs each day.

With most bees and wasps, a queen survives the winter to start a new hive (honey bees keep the hive going even in the dead of winter).

The larva hatches from the egg after a few days and begins to eat its provisions.

When the pollen-nectar mass is completely eaten in about 10 days, the larva spins a cocoon and pupates within the cell.

Near the end of the summer the bee transforms to the adult stage but remains in the cocoon throughout the winter.

Orchard Mason Bee

In the spring, when the weather has warmed up sufficiently, the males begin to emerge by chewing their way out of the cocoons and through the mud plugs.

The females, which are almost always in the inner cells of the tunnel, emerge several days later. One or two weeks may be required for all the bees to emerge during cool weather.

Female Orchard Mason Bees mate soon after emerging, then begin nesting in 3 to 4 days. The bees will forage on a number of different flowers. In wooded areas, they seem to prefer ballhead waterleaf.

The Orchard Mason Bee:

Without a nest or hive to protect, the Mason Bee is non-aggressive and will sting only if handled roughly or if it should get trapped under clothing.

It is less objectionable than the honey bee as a pollinator in urban areas and you should encourage it.

Efforts are being made experimentally to develop large populations of these bees to use as a supplement to honey bees for fruit pollination, especially with the huge decline in European honeybees. You can encourage these pollinating machines to stay in your yard by offering nesting sights.

If there isn't a natural mud source available, or near the nesting shelters, you can dig a shallow hole, line it with plastic, and fill it with moist soil.

A simple drip irrigator can be made from a plastic bucket and a piece of drip irrigation tubing to keep the soil moist.

In urban areas, Oregon grape and even dandelion are commonly visited, in addition to cherries and apples.

Orchard Mason Bee

Nature Study:

In addition to their value as pollinators, Orchard Mason Bees are fascinating insects for nature study. Observation nests can be fashioned from transparent plastic or glass tubes placed in a box that can be opened for observation.

As one of God's little wonders, we need to be aware of what is flying around our yard. Handle the Mason bee with care and they
pose no threat. In other words, don't try to handle them, this is really the only time they will sting, protecting themselves.

Make or buy a Mason Bee house and enjoy they busy workers like I do with my bee house.

Admire the tireless work they do and the benefits they provide us. Like the Hover-fly and other beneficial insects, we need to keep them healthy and happy. After all, they provide a vital service for humans and other wildlife.

Research continues and efforts are being made to build up Orchard Mason Bee populations for pollinating commercial orchards and other crops.

It also shows us how important the natural world is to us.

Even the little things we take for granted.

As a Naturalist, I have respect and some knowledge. The experts or entomologists that dedicates his or her life to the study of bees can help us with new information.

However, it is you and me on the front lines that can really make a difference in helping our Orchard Mason Bees and other beneficial insects. We can stay away from insecticides and possibly offer homes and nesting sights for our garden helpers.

Attract Orchard Mason Bees and Other Pollinators

Leafcutter Bees

Bumble Bees

Ground Bees

Squash Bees

Honey Bees

Protecting Pollinators

Pollination Primers


Orchard Mason Bees, Butterflies, Birds and more. Pollinators are everywhere. Sign up for your FREE weekly 'Gardening for Wildlife' newsletter.

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