During the summer when cutting up broccolis bought at the supermarket. I found 3 pupae over a period of about 8 weeks (each in a different broccoli). All pupae were stuck between the branches of the broccoli. I took a knife with a pointy end and slid it very slowly underneath the pupa to dislocate it.
They were all the same and when I looked closely, I could tell it was a Hoverfly pupa as I could see the two breathing tubes protruding at the end. I placed each pupa in an empty and clean jar with a perforated paper covering. I was hoping to witness the emergence of the fly (I did not know what species would come out) and left it in a cool and well-lit room. Unfortunately, the first two pupae did not give me the chance to witness the emergence of the hoverfly as it happened during the night. But I was more determined with the third pupa and I started to take pictures of the different stages:
This is what the pupa looked like on 5th July, a day after finding it: