Entomologist Needed

I look up this one blue bee and most sources say “sweat bee” but none of the pictures look quite right.  Now odds are it’s just a species of sweat bee that is poorly documented in photography because they move fast and nobody who would care bothered to snap a pic, but I’d like to know with more certainty.  I find them compelling.

It looks more or less like a yellowjacket in size and shape, but the stripes are a pale blue-green.  Their legs and some markings on the face are strongly yellow.  They look almost like they’re a pure silvery blue when you see them flying over the lawn, and the thing that draws my attention isn’t just the color.  The flight is unusual.  They’re trimming the hedges, right?  Barely an inch above the blades, moving fast, never stopping for a full second.

I assumed they were hawking fungus gnats or other soil fly type things, but I also see them go to one particular flower – the coreopsis, specifically this one that is very tall, maroon in the middle with yellow at the ends of the petals.  The flowers are tall enough they blow in the breeze and the camera on my phone will not focus on them enough to get a good snap.

I live in the valley where floweth the Green and White Rivers, closer to the White, in a biome that used to be “oak savanna.”  Who in the fuck are these fucken bees?

…Bonus round.  A real common type of bumblebee here is huge and black with just a little pale yellow at the front and back ends.  Easy enough to ID even if I don’t remember the name offhand.  The real question: I saw a bee-wasp-thing similar shape and color but even bigger and with no obvious setae.  Imagine a thick long black wasp with a few random yellow stripes toward the ends.  Moved too fast to dream of a pic, no friends, flying solo.