Outside my brothers woodshop, there is a burning barrel which we burn our scrap wood in. It is getting full of ash. We have been getting alot of rain, and is saturating the ash in the barrel. Everyday, for the last two weeks, and only the last two weeks, there has been about 30-50 bees gathering the moisture off the wood ash. I have never seen them do this before. What would they be getting from the ash, and why then only in the last two weeks?