That plant brings in a number of different insects, making it a good choice to find subjects to photograph. It is a wasp of some sort. I always called something similar a wood wasp when I was a child, but it was a name I made up. It might be species of the genus Euodynerus, but I don't know the Hymenoptera so well to know.
There are some bees on the flowerheads just below the fly, but they aren't in focus.
It looks like the flowers of spring onions when they go to seed. Insects love them too.