But let clear springs and moss-green pools be near,(Translated by J.G. Greenough, courtesy of the Perseus Project.) The Macmillan edition of the Eclogues and Georgics has a note to this passage that quotes an English publication to the effect that an artificial basin will do if a stream is not handy.
And through the grass a streamlet hurrying run,
Some palm-tree o'er the porch extend its shade,
Or huge-grown oleaster, that in Spring,
Their own sweet Spring-tide, when the new-made chiefs
Lead forth the young swarms, and, escaped their comb,
The colony comes forth to sport and play,
The neighbouring bank may lure them from the heat,
Or bough befriend with hospitable shade.
O'er the mid-waters, whether swift or still,
Cast willow-branches and big stones enow,
Bridge after bridge, where they may footing find
And spread their wide wings to the summer sun,
If haply Eurus, swooping as they pause,
Have dashed with spray or plunged them in the deep.
Last weekend, I dealt with the birdbath in our garden a couple of times: once to fill it, once to adjust the support so that the basin is more nearly level. Both times there were two to four small bees flitting about the birdbath. I was pleased that they did not bother to defend the water. I tried to take a photograph, but found that my phone does not work well for small dull-colored bees against dull concrete.