an efficient and legal way to kill bees is with water and detergent, real sudsy.

I used to live up there (Toronto, Aurora) but now I'm way to far to come up and do a removal. Check with a local beekeeper association about who can do a removal. Spraying with WD40 which is highly flammable, could be very unwise.

Perhaps you can tell us exactly where the bee hive is. Are you sure they're honeybees? Because if they are, you can't simply spray something... the comb, and the honey have to be removed. And, in my case, I take the bees and the brood out alive too.

The only deterent to a new swarm moving in would be to close up the entrance and/or completely fill the cavity with insulation.

I am not having a bee problem at the moment -- I just had two yellow jacket ground nests removed, but I am the author of the 'bee horror stories' thread of a month ago. I just wondered if WD40 would help prevent bees from returning to a hive -- but if it caused a house to burn down that would be 'overkill'! I am also the author of 'beekeeper exterminator false dichotomy' thread this week -- so I did find a beekeeper -- but only after contacting an exterminator and discovering they had one on staff. I sure didn't get help from the Beekeepers' Association of Ontario person I contacted.

Well, associations can be disappointing. I'm sorry you didn't get help. Although I used to live there, I only started keeping bees down here in Indiana. I try to help anyone who calls and I often end up driving miles and miles to find a paper wasp nest.

Honestly, the best repellent is to seal the area. And fill the cavity with an immovable solid - such as cellulose or foam. Fibreglas would probably not be as good.

Any repellent would either be toxic in its own right, or smell awful -- or both.