While targeted at wasp nests, this powder is also effective against bee nests. It kills bees in the nest using the acutely toxic insecticide Bendiocarb and is effective within 24 hours.
If bees do nest around your home using such a nest killer is one option, another is to call in a pest control company to do the job for you. If you can find a local bee keeper they may be able to remove the nest with out harming the bees.
The powder is best deployed on to the nest using a tube, be careful not to inhale or touch the powder yourself. The powder is highly toxic to bees and you will see immediate effects.