Osmia, the Mason bee with a solitary soul!

Text & photos by Stefano D’Aluisi.

With the contribution of Fabrizio Fabbri.

Osmia, unlike social bees, which live in highly organised colonies, lives a solitary life. Undoubtedly, even just for this, it has something in common with the soul of the fly angler.

It is quite common to find the presence of Osmia bee near rivers and streams.

Mason bee is a name now commonly used for species of bees in the genus Osmia. Furthermore, the name describes its habit of using mud or other masonry work.

The Osmia is a genus of bees belonging to the Megachilidae family, unlike social bees, which live in highly organized colonies, they live a solitary life. Indeed, each female engaged in the construction and care of her own nest, chooses nesting sites in pre-existing holes. As well as that, these sites can vary from cracks in the walls, to holes in the wood, chambers dug by other insects, or any type of other small dark cavities.

What further distinguishes the Osmia is the use of unusual building materials. Mason bees collect mud, pieces of leaves, flower petals and even resin. Then, they combine materials to create nesting cells, showing their extraordinary versatility in selecting and using resources. Thanks to their peculiar habit of using mud to build their nests, it is not uncommon to spot them near waterways, such as rivers and streams.

Mason bees can be identified by the unique patterns on their abdomens. Each species of mason bee has its own distinct pattern, making it easy to distinguish one species from another.

Osmia bees are different from common Honey bees from a scientific and behavioural point of view. Conversely, as far as fly tying is concerned, it is possible to imitate Mason bee with the same patterns used for Honey bee and and in some cases Bumblebee.

Solitary Mason bees produce neither honey nor beeswax. But, they propagate in different parts of the world to improve pollination in fruit and nut production.

Mason bees can remain active even in lower temperature conditions than some common bees. Indeed, it is easy to spot them in the early hours of the morning or during cooler periods of the fishing season. This can be an interesting tip for fly anglers.

Osmia’s tendency to be less aggressive than common Honey bee is largely attributable to differences in its social behaviour. Common Honey bee lives in highly organised colonies and defends its hive more hawkishly if it perceives a threat.

Mason bees can actually fly in rain and even snow! The hydrophobic coating on their wings allows them to stay dry even when they are flying in wet weather.