That’s Agapostemon texanus (female), a metallic green sweat bee.
(Believe it or not, "metallic green sweat bee" is very nearly the official name for these things. “Metallic” and “green” are obvious enough; “sweat bee” refers to any member of the Halictidae, based on the habit of some species in salt-poor environments of landing on mammals to harvest salt. The sweat bees around Puget Sound get plenty of salt from other sources, so the source of the name requires explanation.)
Seeing one of those for the first time completely blew me away. Part of the shock comes from the fact that, except for the color, Agapostemon is… well, as bee-like a bee as bees ever get. The head is bee-shaped, the body is bee-shaped, the antennae are bee-shaped… she even carries pollen on the upper segments of her hind legs. (If you think any of that is redundant, I assure you that it’s not. The world of bees is a world of exceptions.) The only really unexpected things about her are her color (and her color is brilliant!) and her size. She’s about half the length of a honeybee, rather like a self-propelled grain of iridescent green rice (cooked, long grain) – with an attitude.
If things like this could fly around without my noticing (and I had no reason to believe that I’d seen the first one to come by), then I had been looking for the wrong things. I was missing part of the story.
And that’s when I really started studying bees.