PLEASE NOTE - this observation is NOT for the bee... it's for the parasitic larvae attached to the bee's thorax.

I did some preliminary digging and found examples of beetle larvae attaching to a digger bee [1] and a miner bee [2]

Apparently the larvae will end up in the female's nest and consume the food she's gathered for her young as well as her eggs. Source #2 (below) is especially instructive about the process which involves the larvae emitting a scent that mimics a female bee's pheromones.

I will note that when we first arrived at this location, I noted a few bees buzzing around the wooden post of a sign. By time these photos were taken 15 minutes later, there were considerably more bees buzzing around and I was observing mating behavior. I don't know if the increased activity and observed mating behavior was due to larvae's presence or whether that increase in activity would have occurred naturally, larvae or not.

I believe the bee is a Cellophane Bee. Observations for this bee and others close by are here:
bees:
https://www.inaturalist.org/observations/160588380
https://www.inaturalist.org/observations/160588381
mating bees:
https://www.inaturalist.org/observations/160588382
bee with beetle larvae
https://www.inaturalist.org/observations/160588384

sources referenced.
[1] https://www.livescience.com/63589-beetle-larvae-parasitize-bee.html
https://www.livescience.com/63589-beetle-larvae-parasitize-bee.html

[2] https://www.honeybeesuite.com/triungulins-a-hitchhiker-riding-a-bee/