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Introducing the Red Mason Bee

7th April 2020

An introduction to the second of our North East Bee Hunt target species: the Red Mason Bee

Mating Red Mason Bees © Ryan Clark

To coincide with the launch of the North East Bee Hunt, we wanted to provide a little more information about five bees at the heart of the scheme. For the second instalment in this series of blog posts, Charlotte Rankin provides an overview of the diminutive Red Mason Bee (Osmia bicornis)

Red Mason Bees are a spring-flying species of solitary bee that you are likely to encounter in your garden and local park. As their name suggests, Red Mason Bees nest in walls and use mud to build and line their nests. Females are relatively large bees, with a light-brown thorax, orange-red abdomen and two facial horns on the head. Males are smaller, with a conspicuous tuft of light hairs on their face and longer antennae.

On the wing from March until June, Red Mason Bees require a supply of nectar and pollen from early-flowering shrubs and garden plants. They occupy a great range of habitats, with urban populations benefitting from the availability of garden bee hotels.

Males are the first to emerge from their over-wintering quarters in spring and can be seen hovering around nests awaiting emerging females. Unlike queen bumblebees and honeybees, female Red Mason Bees single-handedly construct and provision their own burrows to nest within.

Once mated, females seek a place to lay their eggs within. Females are aerial-nesters, building their nests within pre-existing holes and cavities including soft mortar, old timber and large beetle holes. Females also readily occupy artificial bee hotels found in gardens and parks.

Red Mason Bee © Ryan Clark

A nesting burrow consists of a series of cells, each with an egg and pollen separated by walls of collected mud. Cleverly, females lay male eggs at the front so that males emerge first in the following year. Each egg is provisioned with protein-rich pollen that is collected by females on the underside of their abdomens.

To line and protect their cells, females carry back wet mud using their mandibles (jaws) and use their facial horns to mould this wet mud into place. Once completed, the nest is sealed and waterproofed with a mud ‘plug’.

Males and females are only on the wing for a matter of weeks before they die. Within each cell, the larvae develop and overwinter as adults. They remain within their cells until the following spring when they emerge and start the cycle again.

Don’t forget to log your sightings of Red Mason Bee (or any of the species included in the scheme). By doing so, you not only plug the gaps in our knowledge about the North East’s under-recorded bees but actively help inform the conservation of these important invertebrates. Record your sightings here.

Would you like to stay up to date with the North East Bee Hunt? If so, please consider signing up to our mailing list here.

Charlotte Rankin, Local Naturalist

Unsure what to look for?

These annotated images, created to help you, highlight the key features of both male and female Red Mason Bees.