Yesterday I was privileged to see two Large Red Damselflies joined in mating. They were flying around and over my small pond joined together for at least 10 minutes, frequently landing on my various pond plants.
I saw them do what is apparently called the damselfly 'wheel' where they form a circle to complete the mating. A few minutes later I saw another damselfly try to get in on the act which was given short shrift by the mating male as he protected his right for the female to lay his eggs (the two clattered their wings in battle).
I have since googled what I saw and there is more about it here:
What a great joy to have even the smallest of ponds, mine is only 5ft x 3ft but it houses newts and lots of insects visit it on a sunny day.