Masonry Bees
Slightly smaller than honey bees but similar in appearance. These insects are solitary. A single female will tunnel into soft mortar or sandstone to lay her eggs in 6 or so small chambers she builds off the tunnel. Each chamber is packed with food then sealed. Once complete the adults die off. 2 broods are produced each year – in April and July.
What Are the Risks?
The masonry bees are incapable of stinging us. However as these do dig into soft building materials, their presence is indicative of a structural problem – it is probable that soft mortar needs raking out and repointing – a job for a builder. Any remedial work should be carried out during late summer or autumn after all activity ceases.
Note that although solitary, if a wall offers a suitable site for tunnelling then it may attract many individual bees thus increasing the rate of damage.