There are a few good reasons to relocate bees from unwanted places, and there are good reasons to do it sooner rather than later.
This 6 month-old hive was removed from an old Queenslander at Black Mountain in the Noosa hinterland. It is a good example how quickly a hive can grow inside a wall cavity when the conditions are right. The home owner had been tolerating their presence but quite a few bees were ending up inside the house at night and were resulting in stings. Getting stung in bed or while getting up to the bathroom in the middle of the night is certainly more than most would tolerate!
Bees pose relatively little risk to humans if left undisturbed. They are usually happy to go about their business even in close proximity to human activity. Bees in Australia are generally not considered aggressive however all European honey bees are defensive of their hive. Therefore, even an accidental disturbance of a hive can cause the guard bees to attack.
The risk of stings is certainly a good reason to have a beehive relocated. As a hive establishes, its population begins to expand. A relatively small swarm of a few thousand bees can grow to a massive population of 60,000 in just a matter of a few months. It is when a hive reaches its population limits that the risk of stings increases, it is just a matter of probability, the more bees around, the more likelihood of an accidental encounter. Late returning forager bees, attracted to lights, regularly end up inside a houses with a feral hive. For every large hive I have removed, the residents have complained about bees getting into homes at night and stings occurring when they are accidentally handled or stood upon.
I have written a more in depth article about why bees sting here.
Accidental stings usually only result in a single sting, nothing too serious provided the recipient does have an anaphylactic reaction. But multiple stings can result if the the hive itself is disturbed. Some colonies do not like loud noises and vibrations caused by vehicles and mowers and I have never met a colony that will tolerate a whipper snipper or brush cutter. The problem with these devices is not just they are noisy and vibrate, they also throw out grass and sticks in a random manner, and if there is one thing a colony hates more than anything, it is the threat caused by airborne debris directed at the hive. It is this type of disturbance that can result in multitudes of bees attacking to defend their hive.
The risk of stings aside, another good reason to remove a hive from a building is because a beehive can grow to a huge size inside the wall or ceiling of a home. If this colony is poisoned, directly or because someone uses an insecticide in their garden, the spoiling and breakdown of the many kilos of stored honey and other hive material can cause extensive property damage. Ironically a dead hive will eventually attract another swarm of bees, usually within months, and the process starts all over again.
If left unmanaged, almost all bee colonies will swarm each year. This is the natural reproduction of the super-organism whereby they create a new queen and the old queen leaves with half the population. These swarms look for the right cavity to setup a new hive and often it’s our houses that provide perfect homes for the new colonies. To make matters worse, these new hives want to multiply too and the new swarms can end up moving into another part of the house, starting another hive.
Bees will chew plasterboard and will eventually create holes into the inside of a house. Older timber lined houses often have develop small gaps as the timber ages and shrinks and these provide an entry point into the inside of a home. Hives will also happily build their comb around internal wires and pipes, a real problem should these need to be accessed and even a potential shorting or fire risk.
Apart from a home owners concern for their own safety and property there is also a very good reason why beekeepers should be concerned about feral beehives. From a biosecurity point of view, it is much better have a colony in a standard beehive where they can be properly managed and monitored for disease. American Foulbrood is a highly infective bacterial disease that can spread rapidly from hive to hive and can cause huge damage to the beekeeping industry.
Ultimately the sooner a beehive is removed the less it will cost. Quick action can see a job take less than an hour, whereas a hive left for many months or even years can see a job take many hours to complete. When it comes to beehive removals, rushing never saves time, but quick action can save hundreds of dollars.