Why are my garden bees dying?

I read something a while back about them needing a sugary solution to boost them up as they do tend to lag
will try to see what it was
x x

You don't say where you live - if in the country, it could be spraying on the surrounding fields which has caused the problem. But there are huge problems with bees currently - they are dying in their thousands and no one's really sure why, in particular honey bees. There is an infection in some hives that kills them, and other theories about why - genetic modification of plants seems to be one of the contenders, plus certain pesticides (particularly agro chemicals) and fertilisers. There could be just a very simple explanation though - it might just be the weather - its chilly, damp and we keep having torrential downpours and storms. Well, here in London anyway - its thundering and lightning and stair rods as I type... again.

If these are bumble bees, then as Bamboo says, the most likely explanation is that they have hypothermia! Or as they are cold blooded creatures, their metabolism just slows to a halt once they are chilled. If the weather doesn't warm up, they can't fly away and just die where they are. If they still have some life, bring them into the warm and feed them with some honey or concentrated sugar syrup. Then let them outside again once it's warm and they should fly away.

I had this happen and it coincides with rain in the evening. they get wet and then cold. found 5 the next day. some i thought were dead but next morning they were still alive and when they warmed up in the sun they were off. still some casualties though.

Yes, i'm seeing a lot of dead bumbles at the moment - I think it's because of the cool wet weather They get waterlogged. :-(