I recently spent a pleasant day down at Robinswood Fishery (Surrey) where the Mayfly season was just starting. The main lake is often well fished and many people start there because they can see fish cruising just below the surface. The day I was there was no exception, except (!) there were only two people fishing - myself and a friend.
However, it was not all plain sailing for me, as the first fish missed was one that came up to look at the fly, possibly noticed something wrong and turned away. I think it likely that the fish could see the nylon tippet. I could certainly see it, lying on the water. Consequently, I degreased the tippet quite regularly and after that I started to catch fish.
Most were caught on extended foam bodied Mayfly adults tied on short hooks. I find this pattern quite successful as the hackle is tied parachute style and the fly sits nicely on the water. I have caught many trout with this type of pattern. Some fish were taken on Sedge patterns (CdC patterns and Elk hair patterns) and a few on a hatching Mayfly / emerger pattern. The fly had to be sitting on the surface for the most part, but I also had interest with some patterns that sank just below the surface, hence the emerger.
I have not seen many large hatches of Mayfly yet, so I hope that the season lasts a while longer so I can enjoy a few more days like this one!
I think that I may have missed the season, as I have seen very few Mayflies recently and certainly nothing to tempt the trout as in May. But I was out last week and did see two Mayflies dancing in the evening breeze.