If you have honeybees inside of a cavity of a house or shed, removing those bees may require opening up walls or ceilings and involve subsequent repair. It can be tempting to try to poison the colony rather than remove them, to save money and avoid inconvenience. But killing the colony may create a situation worse than existing with the bees.
While the colony is alive, the bees are maintaining the comb. This means that they are storing and capping cells of honey, caring for brood (larvae and pupae) and generally cleaning and protecting their hive.
If the colony is killed, the comb is no longer protected or maintained. At a minimum this will mean a gradual breakdown of what the bees left. Any brood still in the comb – which is not mature enough to emerge as adult bees – will die, rot, and stink. Honey which is capped can remain for a long time, but any nectar which is not dried and capped will eventually ferment – again giving off a sour odor.
The unprotected comb will attract vermin. It’s possible that the unprotected colony will attract “robber bees” from other nearby colonies which will tear open the comb to steal the honey. It’s likely that the comb will draw wax moths and beetles which will fill the comb with their webby or slimy deposits and grub-like larvae. Roaches will be drawn to forage on the remnants and rodents will find a feast in the protein-rich brood. A poisoned hive can become a greater problem requiring extermination than the honeybee colony ever was.
Breaking down comb can cause property damage. The effects of time or vermin on abandoned comb can cause honey to drip inside of the cavity where the honeybees lived. This could seep through walls or ceilings, leaving stained, sticky, smelly deposits requiring eventual cleanup and repair.
Proper removal will attempt to avoid all of these issues, plus saves the colony. If I remove a colony from a structure I attempt to remove all comb to avoid the issues described, and seal the bees’ entrance to avoid future honeybee infestations. Removal is just the first step; preventing future colonies from moving in (which is extremely common) is the long-term goal. Although there is usually a cost for a removal, the cost of not doing a removal properly could be much higher in the long run.