Might be same species, or closely related to the ones I was seeing all the time. I cannot be sure they were Nootka roses but good chance... was in Renton at the time (now in Bellevue). At the time I would walk by patches of Himalayan blackberries and the rose bushes looking for (Northern) Pacific Chorus frogs (Pseudacris rigella - one of my favorite species) when I started noticing these guys. I likely saw many dozens over a couple/few weeks. I too was at first looking at the rose hips when I happened to notice something very tiny, finally getting to see them contort their body a bit in order to get that ovipositor into the rose hip. (I noticed your pic as I came back to BG to see if I could further speciate any of the Hymenoptera I had pictures of, and to place them taxonomically so I could see where the few dozen I've captured exist on that taxonomic tree (which seemed much more simple of an idea before I started trying to do so)

Mine were posted 3 years or so back living in Renton. There are a lot of rose bushes around here (native species growing wild and planted), but when I have looked, I've not seen the buggers here, although I've not spent a good deal of time looking)

Not mine, but just stumbled upon this nicely collected series (from Victoria) of a female going through the motions, so to speak:
Victoria Megastigmus series

Mine are here:
Renton Megastigmus series

Moved from Ants, Bees, Wasps and Sawflies.

See reference here.

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