bees interested in wet cardboard?

[windfall]

I was just out on our back porch cleaning up some craft stuff the kids left in the rain for a couple days.
All of the corrugated cardboard had bees on it. Not huge numbers but a at least 20-30 and they appeared to be making round trips to the hives (some coming some going)

What are they doing? I have noticed in the shop we will get bees checking out the sawdust piles when we process damp and wet wood but usually it is just 1-6. Something about damp cellulose?

[BlueBee]

My hypothesis is they are attracted to an order emitted from wet cellulose materials. 

Check out all these bees in my decaying cellulose (peat) on a coolish 57F September day.  My bees seem to be sucking up more water from the peat now than they did during the heat waves.  It's non stop back and forth to the water hole all day.  Go figure.  Hopefully they're using all that water to build up strong winter broods.

[Michael Bush]

Bees love a water source they can suck up without drowning...

[SerenaSYH]

Oh, this is so cool! The honeybees are taking a sponge bath! lol!

Love the pics and Michael's comment!

[windfall]

It may be a simple as that, safe drinking. They do appear to be drinking from the cardboard. Most are gathering at the bottom "draining edges".

It's been nothing but rain here for 3 days, water everywhere so I hadn't really thought of them searching for a water source. I still kind of suspect there is something attracting them to it....

[caticind]

At our bigger yard, we found a spot where the bees gather to drink, 30+ at a time, from damp sand at the end of the a creek.  A safe place to drink is always well appreciated once they find it.  This is also why dripping hoses/faucets are popular.

[Dimmsdale]

I've also heard that Bees prefer a water source with a distinct scent so that it is easier for them to direct everyone else to it.  That's why swimming pools are so often raided.

[forrestcav]

my bees found a good spot too, sort of. I noticed last thursday several of mine were on a lead that had laid out in the rain. I guess it was a good safe spot. Might be a good idea for a shallow pan in a pinch.