Bumblebees get thirsty too. Water pooled on the lid of a compost bin on the allotment after a brief rain shower. As soon as the sun came out a considerable number of bumblebees started buzzing back and forth hydrating at this new oasis. The shallow indentation of the lid was just the right depth for them to alight and drink. On dry days I will get in the habit of splashing some water on it to make a bee bath.