On Fri, 25 Apr 2014 16:35:52 +0100, alan wrote:

Mine are mason bees - they use mud to make compartments in reeds or
holes drilled by OTHER insects. Even though they can sting they are
very docile. They are solitary bees - no queen, no swarms, no honey etc.

What diameter and depth of hole do you use (well, offer to the bees)?

And woudl the bees reuse a hole -- lots of the commercail ones have some sort of
inset or straw, and it that meant ot bechanged annually?

Thomas Prufer