Thanks everyone.
I did a bit of insect macro work a few years ago with my D300 and 105VR and sometimes a ring flash.
Yesterday's was with the newer body, plus the 300mm and extension tubes.
But the things that really helped nail the shot were
- Plenty of thirsty bees (almost queing up at times!)
- Full sunshine (bright enough to shine through its abdomen, plus warmth to get them active)
Look carefully below the bee's head:
The orange shape is its tongue, dipping into the water.
There was no lapping - maybe it is hollow and they use it like a straw??