This scary bug is a parasitoid wasp in the Ichneumonidae family, having a quiet lunch:
There are a great many species of these, and they are hard to tell apart, but I think this one is a Gasteruption jaculator.
They lay eggs on the larvae of solitary bees using the long drill (ovipositor) you see in the photos. After hatching, the wasp's larva consumes its still living host.
They can't sting or use poison like regular wasps, but the females will use their ovipositor in self-defense when cornered, and getting stung with it hurts like fuck smarts a bit.
All in all, not the most pleasant of insects, especially if you like bees.
Here's an older photo of this species, in which it seems to be looking at me quizzingly:
I escaped unharmed.