Mystery Guest

Wasps? Early Sunday evening (not quite dusk) I went out to pick some basil for a meal of tomatoes and buffalo cheese drizzled with balsamic vinegar. I stopped to admire the leek blossoms (aka seed heads), and spied this amorous couple. I ran back in for my camera. The light was a little low, and my hand wasn't very steady, but you get the idea. What are they?