Insect and Spider Identification: CLOSED: wasp (?) hatched out of hairy cocoon, 4 by spoonlegs

spoonlegs wrote:
This wasp (or sawfly?) hatched out of a hairy cocoon that I brought indoors after it fell off of our outdoor solar oven. I thought it would be a tiger moth, so when the wasp emerged, I thought it might be a parasitic wasp. But then I saw that some sawflies have rough brown cocoons. However, this critter is thread-waisted, and aren't sawflies all thick-waisted? This critter has two spurs from the tibiae on its middle legs, which is a characteristic of Thread-Waisted Wasps (Sphecidae, subfamily Sphecinae), but they lay their eggs in the ground . . . This critter has a small head, the wings are metallic blue-black, and the lovely antennae are dark with a yellow zone in the middle of each thread, and they move fluidly in a way that reminds me of a moth's antennae.