A survey of Victorian House

We recently undertook a survey on a substantial Victorian house and noted bees had swarmed in the rear chimney flue/pot. It is possible that these are masonry bees and if this is the case they could cause significant damage to the brickwork. It is our understanding that these bees are protected and as such can normally only be eradicated at the end of the year, probably November or December, after which it is important to install mesh to prevent the bees from swarming the following year and indeed to repair the masonry.