Look at those antennae!
Like so many things, when you learn a new species you start seeing it everywhere. Were they there all along? Or did I just notice them because they had a population explosion? My first thought is that the former seems more likely.
I don't mind seeing bee-like flower beetles everywhere. They are neat little critters, with fuzzy, clumsy little bodies and delicate fan-like ("lamellate") antennae. Lamellate antennae are typical of the scarab beetle family, of which there are more than 30,000 species.
"Hey baby, wassuuuppp"
Beetles and other bugs use their antennae for smell. They were all over the cactus blossoms. Glancing into a flower, you'd see a couple bee-like flower scarabs tumbling and rooting around. Are they gregarious? Were they mating? Or are they just that common?
After doing a little research, it looks like all of the above are accurate. Some beetles are only active in their adult forms for a few weeks, so the clock is ticking with regards to mating and eating. All the adults emerge at once, so they go from absent to super-abundant.
After mating, the female will lay her eggs in rotting plant matter and then die. The larvae will feed on decaying deciduous trees and graminoid roots for 3 or 4 years before emerging as adults, and re-starting the cycle. Because these creatures spend most of their lifecycle out-of-sight underground, and then suddenly flushing for a few weeks in spring, they are both rare and ubiquitous, everywhere and scarce, depending on the season. It is amazing that, if I hadn't been looking when I was, I could go an entire 11 months without seeing one of these beetles.