[Chicken Pete]

My apologises if this is not directly related to growing Vegetables,etc.

Whilst out walking the other day I came across hundreds of dead bees under a tree,could anyone offer an explanation as to what may have caused this.  the tree was nowhere near a field that might have been sprayed,etc so am very puzzled as to what may have caused so many bee deaths.

Thanks

[kegs]

Was it a lime tree?  The nectar of this particular tree is toxic to bees.

[Chicken Pete]

Yes, I believe it was a lime tree!!!
Why would bees be attracted to this tree if it is toxic to them?

[kegs]

Not sure really.  I used to work  for a company who's Head Office was based in a large country house with a tree lined avenue and under the lime trees were piles of dead bees!

The Kew web site gives a bit more information on the trees, but I think it's that the pollen make the bees dozy but the weather conditions can kill them off if they don't recover in time:

http://apps.kew.org/trees/?page_id=131

[operabunny]

Oh, poor bees! 

[Kate and her Ducks]

How interesting, I had never heard of lime being toxic to bees, in fact I had always been told it was an important source of forage for them.

Looks like it is a bit of both:

http://www.beekeepingforum.co.uk/showthread.php?t=7804

[sunshineband]

We have lime trees planted in our adjoining street. Never seen dead bees so hopefully they are a tyep that are not toxic 

[Swing Swang]

Some thoughts:

Maybe a swarm had settled in the tree for a while, and the dead bees had dropped off the cluster. As a swarm often has 1000s of bees and July 24 is quite late in the season there could have been a high proportion of bees that had reached the end on their six-week summer lifespan. In addition the swarm could have flown through an plume of insecticide which resulted in a high attrition rate once it settled. I don't think that the lime tree itself has to be implicated. In fact I think that lime is quite attractive to bees for 'honeydew' - the sweet plant exudates than come from the leaves rather than the flowers.

SS

[ANHBUC]

Here is a quote from beesfordevelopment.org which might explain it.

"Certain lime tree species can poison the bees themselves but do not affect people. This is because the honeybees lack the enzyme to break down the sugar, mannose, present in the nectar and which paralyses the honeybee."

[sunshineband]

Some thoughts:

Maybe a swarm had settled in the tree for a while, and the dead bees had dropped off the cluster. As a swarm often has 1000s of bees and July 24 is quite late in the season there could have been a high proportion of bees that had reached the end on their six-week summer lifespan. In addition the swarm could have flown through an plume of insecticide which resulted in a high attrition rate once it settled. I don't think that the lime tree itself has to be implicated. In fact I think that lime is quite attractive to bees for 'honeydew' - the sweet plant exudates than come from the leaves rather than the flowers. SS

I thought that the 'exudate' was actually relaesed by aphids, that feed on the shoots and overfill themselves 

This is what drips onto the leaves and then black sooty mould grows on it 

Bees don't get involved as far as I know 

[Kate and her Ducks]

you're right about the aphids making honeydew but some bees do actually harvest this and make it into honey.

[Guzzik]

This might have been a swarm that couldn't find another area to hive in.  Unfortunatly this does happen.