Mystery flying object

Thoroughly enjoyed the Sounds of Spring walk with Charles Cuthbert yesterday and learned loads - and didn't even mind the snow that joined us!  Many thanks to Charles for that.
Going through the photos later, I was a bit taken aback by this one - taken along the North Wall area. I hadn't remembered a large bird being visible at this point - and it certainly didn't appear in any of the others taken in the same sequence. As I zoomed in to try to re-identify the bird (a linnet I think), I realised that it was not a bird of prey hovering in the background - but something else entirely, Quite what it is I don't know - but this 1/4000th of a second snap has given a new meaning to the phrase 'insect-eating bird' - or is that 'insect eating bird'?
If anyone can identify said insect I'd be interested to know just what decided to make such an unexpected appearance!