How To Bring Valuable Mason Bees To Your Garden

How To Bring Valuable Mason Bees To Your Garden

You want to promote wild bees like the mason bees, give them nesting space and food, and thus actively help to preserve our nature? Find out here how this can be done in your own garden with simple means.

Insect mortality and especially bee mortality have become an omnipresent topic. Bees make an immense contribution to the preservation of biodiversity – not least, they ensure that we can harvest fruit, berries and vegetables. In addition to honey bees, which live together in states, there are numerous wild bees that live individually, which is why they are also called hermit bees or solitary bees. There are a total of 700 known species in Central Europe, but many of them are severely endangered as their habitats and food sources disappear.

Red mason bee and horned mason bee


These wild bees look very different, have very different sizes and live in diverse habitats – among the best known are the mason bees. They are also often found in domestic gardens. The two most common species are the horned mason bee (Osmia cornuta) and the red mason bee (Osmia bicornis). The latter was even named “Insect of the Year 2019.” Mason bees grow to about 8 to 14 millimeters in size, have a furry, black body. Good distinguishing feature is the reddish colored abdomen.

The horned mason bee prefers more mild locations and begins its flight period earlier, already in March, the red mason bee only in April.

How To Bring Valuable Mason Bees To Your Garden

Mason bees do not sting


One thing in advance: mason bees are not dangerous for people at all and do not sting. In this respect, you do not have to fear these animals – on the contrary, they can be observed very well. This is particularly successful if you offer the mason bees a nesting aid. Since they are solitary bees, the insects do not swarm. Perfect for your garden.

Mason bees fly out soon in the year


An exciting fact is that mason bees begin to fly in early spring – the horned mason bees usually as early as March. The young ones hatch from their nest, where they have spent the winter, on the first warmer days of spring. First, the males appear and wait ready to mate with the females that hatch later. The fertilized females begin to lay their eggs in suitable places, such as holes in rocks, cavities in walls, or crevices in wood. They provide their offspring with food in the form of pollen. The flight period of mason bees ends in May or early June, after about 6 to 8 weeks.

A one-year life cycle


The females then seal these cavities with clay and saliva, creating individual chambers. In these chambers, larvae develop from the eggs, which later pupate until the fully developed mason bee finally bites open the clay seal in the spring, flies out and begins work – this one-year cycle then starts again.

Nesting aids for mason bees – nesting blocks.


Therefore, nesting blocks – for example, wooden blocks, which have holes in the size of 7 to 9 millimeters for mason bees, are particularly suitable for this purpose. With a depth of up to 15 centimeters, mason bees can build about 5-6 chambers in a row for their eggs. In our case, a wooden block worked very well as a nesting aid and was quickly accepted by the bees. The holes should be ground smooth without sharp edges.

Such wooden boxes can also be made yourself. In addition to wood – hardwood is best – equally long cut pieces of reed or bamboo poles, cardboard tubes or bricks are conceivable as cavities. We bought our hardwood nesting block from a conservation portal. Look for solid workmanship, these specialty portals often offer higher quality than the nearest bargain retailer. Also, refrain from using wood preservatives.

The right place for the nesting aid – 5 tips:

  • Install the nesting aid in a sunny, dry location that faces south, if possible.
  • In addition, the place should be protected from wind and rain.
  • The nest box should be sturdily fixed and not sway.
  • Choose the place so that the wild bees can fly freely to the nesting aid and the entrance is not covered by leaves, for example.
  • The nest box should also not be moved to another location in the meantime. Relocation or removal of the nest box is not necessary due to the peacefulness of the animals. Mason bees that have sought a natural nest in the garden should support them and secure the site. The animals are under protection.


What do mason bees eat?


Mason bees feed on pollen and nectar of all kinds of plants that bloom in spring. They do this by flying to flowers, flowering shrubs and trees, and thus pollinating these plants. Mason bees are excellent in fruit growing, they love to fly to fruit trees. Only in this way these plants continue to exist or bear fruit. If their garden or the space in the immediate vicinity offers some of this, the insects are already provided for, their flight radius is no further than about 250 meters. They pick up the pollen with the underside of their body – the so-called abdominal brush – and transport it to the cells where they lay their eggs. Creating a natural garden – this is how to do it

Mason bees are very efficient pollinators


By the way, mason bees are very efficient at pollinating plants. Due to their transport of pollen on their abdomen, almost every visit to a flower results in pollination. The single mason bee thus pollinates many more plants than, for example, a honey bee.

In our house, the nesting block is attached to the garden shed. The working mason bees do not interfere at all with the use of the hut. They are absolutely peaceful animals. It is really exciting to observe how in spring the many holes of the nesting block disappear more and more and are neatly closed on the outside with “bee mortar” until at some point really every opening has been used by insects.

Since the holes on our nesting block have different diameters, it was also possible to observe different species of wild bees at work – but especially on sunny days, mason bees can be seen. Considering that several eggs are laid in each hole, the wooden house provides accommodation for a really stately number of wild bees.

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