Black fly with yellow markings

Black fly with yellow markings

Observation - Black fly with yellow markings - UK and Ireland. Description: I found this fly in my local park, you can see the plant on which I found it. There were a couple on this plant, some on the under side too. I don't really know what this is so any help would be appreciated.

I found this fly in my local park, you can see the plant on which I found it. There were a couple on this plant, some on the under side too. I don't really know what this is so any help would be appreciated.