The mayflies have just begun hatching and the first half of the season is always the best. The trout and grayling need a few days to get used to the big critters floating by. Mayflies are more than twice as big as the second largest mayfly species.
It's obvious that the big insects can bring the biggest fish to the surface and that alone is enough an attraction to get out there and enjoy this hatch. But I really do enjoy the hatch itself. Because the insect are so large, everything is easily visible. Take a small net and try and catch some of the drifting nymphs and emergers. It's not hard to get one and watch it break free from the nymphal shuck.
The mating dance of the mayflies is also quite a spectacle as the flies dance up and down in the air before mating. And of course, when you really hit the aternoon of one of the big spinnerfalls you're in for a special treat. For once, the fish clear knows that spinners are easy prey and the simply sip them off the surface, and even big trout make only a small dimple. The big challenge here is getting the trout/grayling to select the artificial among the hundreds of flies on the surface
The Danicas make it even harer sometimes as they can vibrate, sending out many, small ripples, which not only is impossible to imitate, but also clearly becomes a trigger for some fish. They can really become selective towards the vibrating spinners.
This is the Danica spinner (male). It undergoes quite a transformation as it sheds it's subimago skin. It goes from a darkish olive to this almost white with brown markings. The tails go completely black and very long and the wings go from a dark grey to these clear ones with black veins.
As for flies, I mainly use a French Partridge (in the PoD), but as the season progresses it becomes more and more inportant to have a closer imitation, preferably with an extended body and more defined lines. They don't hook as well, but often they're needed to rise a fish.
The hatch goes on for about three weeks, so get out there and enjoy it while it lasts.
Have a great weekend!