Life history of the Red & Blue Mason Bees

The Red Mason Bee (Osmia rufa)

The Red Mason Bee is widespread in England and Wales and particularly likes the range of flowers and trees found in domestic gardens. It is active from late March to the beginning of June and a more efficient pollinator of fruit crops than the honeybee. By attracting them to your garden not only will you notice improved fruit crops - apples, plums, pears, strawberries and raspberries - but the bees also visit a wide range of garden flowers.

Life history of the Red Mason Bee (Osmia rufa)

The Red Mason Bee is a solitary bee. That is, each nest tube is the work of a single female working alone; unlike the honeybees and bumblebees, there is no worker caste of sterile females.

The bee is widespread and common in England and Wales and extends north into Scotland as far as Edinburgh. It is widely distributed in continental Europe and even penetrates into the Mediterranean region.

Red Mason Bee Quarrying Mud for Sealing a CellThey are covered with a dense, gingery fur. The males are 6-11mm long with a dense tuft of white hairs on the front of the head. The more robust females are 10-16mm in length. Their heads are entirely black-haired and is larger and squarer than that of the males. This is to accommodate the large muscles associated with the powerful jaws used to excavate mud.

Female Red Mason Bee at Nesting Tube EntranceThe species has an annual life cycle. Males and females emerge in early spring (late March to April) and mate. Females then seek out suitable nest sites usually beetle borings in dead wood, hollow plant stems, or irregular cavities in stones and old walls. Each nest tube comprises a series of cells. The female starts her first cell at the back of the nest. She makes 10 to 15 foraging trips to collect sufficient pollen to provision each cell. The pollen is mixed with a little nectar and this acts as a food source for the single egg, which she lays immediately before sealing the cell with a mud partition. The process is repeated until the tube is filled with a row of about 6 to 10 cells.

Completed Mason Bee Nesting TubesFemales finish nesting in early June. Being a solitary species they will never live to see their offspring. However in the comfort of their nests, the eggs hatch into larvae, which feed on the pollen/nectar mixture. After moulting 4 or 5 times, the full grown larvae spins a tough brown silk cocoon and pupates. The new adults form in September and remain in the cocoon until the following spring when the new generation of adults emerge and the cycle begins again.

Females tend to nest close to where they emerge and the design of the Oxford Bee Company nest box is such that it will attract a number of nesting females, many of whose daughters will re-use their natal nests the following season. Thus a permanent nesting population will be established in your garden. This can be enhanced by adding further nest boxes if desired.

The Blue Mason Bee (Osmia coerulescens)

The Blue Mason Bee, Osmia coerulescens is an excellent pollinator of garden herbs and visits a wide range of garden flowers. It is smaller than the Red Mason Bee and makes its appearance slightly later and continues nesting until the end of July/early August.

The females are dark blue-black bees with metalic reflections, about 10-12mm long, sparsely covered with brown hairs those on the abdomen in the form of a narrow, dense, flattened band on the hind margin of each of the segments. The dense brush of pollen transporting hairs (scopa) on the underside of the abdomen is jet black.

The males are slightly smaller, more slender in build, distinctly metallic green and clothed with pale hairs. The males often appear first and loiter around the nests seeking mates. They are active for about three weeks.

Their life cycle is similar to the Red Mason Bee except that it is starts nesting in late May and continues until the end of July/early August. It also uses leaf mastic rather than mud for building nests.

More Information:
Mason Bees: Frequently Asked Questions,
An Introduction to Bumblebees,
Bee and Ladybird Nests from the Oxford Bee Company,
Chris O’Toole's book: The Red Mason Bee: Taking the Sting Out of Beekeeping.


Pictures and information provided by the Oxford Bee Company.
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