While I was photographing a Nisquallia olympica pair mate guarding, this tiny wasp (I think) swooped in, touched down on the female's head and swooped away again. The contact lasted much less than a second.

Even zooming in, I can't see any hint of halteres, so I'm guessing a parasitic wasp.
It could be just a coincidence, but the landing sure looked directed.
I have no images of the right side of that female's head, so I don't know if there was an egg there.

Any hint of an ID? (If not, the image can be frassed.)

We did also see a dead female Nisquallia that had been hollowed out, possibly by a parasite.