Osmia bicornis

It is sometimes called the red mortar bee because females can excavate soft mortar joints, which over time may weaken masonry.

The species occurs across much of the Palaearctic, from Sweden and Denmark south to Spain and Morocco and east to Japan.

In Britain it is widely distributed as far north as Perthshire; it is also a recent arrival in Ireland.

There is one generation a year, flying from April, or occasionally late March, to June and sometimes July.

Males usually emerge about two weeks before the females.

The bees pass the winter as fully formed adults inside tough reddish-brown silk cocoons and emerge the following spring.

Adult females can live for up to five to six weeks.

Females nest in pre-existing cavities of many shapes and sizes; recorded sites include key holes, pocket watches, flutes, glass tubes and empty snail shells.

The partitions between cells and the final nest plug are made of mud.

Mud is carried to the nest as pellets held in the jaws and tamped into place with two conspicuous prong-like projections on the female's face.

It is polylectic, collecting pollen from plants belonging to 19 different families.

Besides pollen flowers, it visits many plants for nectar, including fruit blossom such as raspberry, plum, pear and apple.

Males do not defend territories but search for females within overlapping home ranges centred on food plants, a mating system described as scramble competition polygyny.

It readily nests in cut bamboo stems or cardboard tubes, is an important wild pollinator of fruit trees, and has potential as a managed pollinator of fruit crops.