I was asked:
"[We] have a birdbath, large water-filled patio tubs and small saucer of water on our patio. Last year, and now this, we have found lots of bees trying to drink from these places, but have found a significant number drowning. We try to keep the water levels high, and have tried floating things in the water to help them get out if they fall in, but are concerned about the numbers drowning. We have lots of bees drinking on warm days and it can be a bit hard to get into the garden – and we don’t want to disturb them.
What can we do to help more bees survive?"
"The best thing to stop bees drowning is to provide what I might best describe as a shallow ramp down into the water, like a very gentle beach. The bees will then walk forwards and drink from the damp edge, without drowning. Floaty things generally don't work.
If they are honey bees in your garden, they should not really bother you, but if there is a large colony (wild or kept) near-by, I can understand how it might be a bit of a pain. To stop the bees arriving, I suggest that from time to time you leave the bird bath dry for a while; the bees will soon (give it three days) learn to go elsewhere. You can then refill the birdbath, and repeat the trick if the bees rediscover it."