Seen on Hawthorn flower. I cannot identify either insect - nor do I know whether this is mating or predation
No interactions present.
I think it's a Robber Fly eating Hawthorn Fly.
The eater is Empis tessellata, I think, which on size makes the victim Bibio marci. These (and other Empidids) are often seen mating while the female is well into dinner. I have not discovered if the male arrives while she is distracted, or whether there is a bit of courtship feeding, but it is a very common thing to see.
recording wildlife with The Recorder's Year on www.hbrg.org.uk/TRY.html.
Looks to me like Empis tessellata
Many thanks for such expert information
Lat/Lng: 51.853, -0.549
OS grid ref: TL000181