We will normally encounter three types of bees,
The native bee which does not sting and produces a small amount of honey these are a very small bee.
The European bees produce a lot of honey and sting which a lot of people are allergic too. Generally speaking we do not like to kill bees as some species have now become an endangered specie mainly due to pesticides used on cropping. During spring bees will often swarm this is where they are looking for new areas to establish a nest and unfortunately sometimes the wall cavity in a house can be a common area they want to use, this is only time we will generally do a treatment but we prefer that you try and leave them a few hours to see if they will move on by themselves. Quite often the bees may just be resting and will leave within a matter of time by themselves if this is not the case we then will normally place permethrin dust in their entry point which will eradicate the colony. If you find a big swarm on a wall or tree it is just best to leave them alone and give them time to leave at their own choice alternatively you can call a beekeeper who may come and try and get the queen and the rest of the bees will leave.
The Mortar bee get its name as the female will often burrow holes into mortar in between brickwork, they are not renowned for their honey production and a general pest spray to the external walls will assist with the control of them.