I have always understood wild bees are smaller and darker in colour than our domesticated honey bees - but I stand to be corrected. As Marnie suggests, there could be a domesticated hive within your area, or there could be a wild hive or two in a tree or behind the wall boards of a building and I guess even domesticated honey bees will swarm in a tree or find a cosy space in the side of a building! I believe swarming time happens in Spring.
Regards,
Dawn.
PS I realise though Helen you are not talking of a swarm.
Edited 2 time(s). Last edit at 08/09/2016 01:51AM by Dawn.