I recently found this ugliness on a red huckleberry bush. I have never seen such a thing in my life, and I managed one quick photo before it flew away. It turns out to be Myopa rubida, also known as the red thick-headed fly—a name as hideous as the insect.
What little I’ve been able to learn is that this fly and it’s close relations are predators on native bees. According to BugGuide.net, this type of fly parasitizes bees by chasing them down in flight and laying eggs directly in the bees body in the vulnerable spot between the sclerites—the protective outer plates. Once the eggs hatch, the larvae can then eat the live bee.
This specimen was just sitting on a flower in a bush that was loaded with native bees. Perhaps it was looking for a victim to nourish its young, assuming it was female. If male, maybe it was looking to mate. I don’t know what the adult flies eat, but perhaps they take a swig of nectar now and again. Who knows?