This summer, in Carden, we had periods when our cabin was shared with lots and lots of flies. A fly swapper was used but its effectiveness was limited, and so was the fly tape. So we basically just learned how to live with them.
Nevertheless, we were amazed when we found this critter below that was hunting the flies! We didn't know what it was but was grateful for it - until we found it upstairs where we sleep. Then the feeling became quite cautious about this dangerous-looking fly-killer.
Well, I just came across this post (by Ben Cruachan) this morning that tells me what I saw was a Robber Fly (Family Asilidae)! Good to have some idea now...but I don't think I will ever find out what species it is.