Crab Spider with syrphid prey

Crab Spider with syrphid prey

Observation - Crab Spider with syrphid prey - UK and Ireland. Description: I have looked at this photo for 5 years without spotting the crab spider! I know what the spider is, but what is the fly - genus anyway if poss?

I have looked at this photo for 5 years without spotting the crab spider! I know what the spider is, but what is the fly - genus anyway if poss?