Hello, I must bee going!

In spring, bees set off in search of suitable sites to establish new colonies. For some reason - perhaps the colours/patterning of the bricks - our house is a favoured stopover on these migrations. So, every September-October, we'll see the odd bee buzzing outside a window, then several of 'em, then a large swarm, then they'll be goneski. We don't bother them and they don't really bother us. That said, it's probably just as well we don't have a flower garden or they might enquire about long-term accommodation.