Bee Problem - Update

I have a large (15X22) deck and I have bees somewhere under it. The deck is only a few feet above ground and I cannot see the nest. What I see is bees going down between the boards. I have sat there observing and the bees are going down between the deck boards over a very large area so I cannot pinpoint where the nest is. I do not like sitting on the deck with the bees coming and going.
I tried spraying bee and wasp spray between the boards in areas I thought the bees were but that did no good. I do not want to buy dozens of cans and spray between every board. Is there a good homemade repellent or killer that I can put in a sprayer to get these things?
help


UPDATE:
So.

The bees were bumble bees.
I called an exterminator and it was a waste of time as he wanted me to rip up deck boards and locate where the bee nest was. If I knew that I would not have called him. Fortunately I expressed my disappointment with him and no money was exchanged.
I did remove deck boards and I did find the entry point. As it turned out, the bees were in my basement wall. I could hear the buzzing. The were coming in at the point where the siding ended and the parging started. There must have been an opening so I got some spray foam and sealed in the area. Doesn't look very good but, it is under the deck
I then went into the basement and listened for the buzzing. I punched a half dozen very small holes (through the vapour barrier and insulation to the foundation wall) and stuck a Wasp and Hornet spray foam nozzle (a small nozzle extension came with the can) and started spraying it into the space. Sure P's off the bees!! I used 3 cans of the stuff, probably overkill but just to be certain they are all dead, no more buzzing in my walls and no more bees coming to the deck.