Most of the rivers in Brittany and Normandy are excellent for the hatching of this great mayfly, but this phenomenon also occurs in other regions of France.
Being in the right place at the right time
I was able to make an outing on the Ellé river where the mayflies are coming out these days. It is indeed necessary to follow the evolution of the hatchings to be on "THE" river of the moment, because they can be shifted even from one river to another at a few tens of kilometers.
The hatchings often take place in the late afternoon. At this time, I usually go on the water around 16 : 00 for a short session when I have a free day.
As soon as we arrive, some flies are already coming out and the exuviae (nymphal envelopes) are dying in numbers. This is a good sign.
The trout start to gobble. The small ones first, then some more beautiful fish. Posted, I wait for the nose of the beautiful trout to pierce the surface. The gobages are often more discreet and the wave (water displacement) more important. These are the ones I'm looking for!
Adapting your editing and using the right imitation
You will have to observe what is happening on the water to choose the stage that the trout take and use the appropriate imitation. I personally use a tapering leader of one and a half times the rod length finished with a 15° tip.
I often ride the sub-imago stage which in many cases is what trout take. But this is not always the case. Sometimes a surface nymph, or the spent can be more specifically targeted by trout. It is necessary to observe what drifts on the surface and the type of gobbling.
Today, my favorite fly works perfectly and several trout will come to take it sometimes delicately, sometimes in a very explosive way. A real treat!
The trout can gorge themselves and have a very round belly. They are very powerful at this time because they are loaded with protein!
Good approaches are often rewarded
The beautiful trout often come out at this time. You have to pay attention and spot them if you want to catch them. Catching a small trout near a beautiful fish can ruin everything. One step too many, a noisy movement, a too flat landing and it is the escape.
Do not hesitate to lengthen the point. Sometimes, I mount a smaller imitation to use a 12° tip to be more discreet. It is also necessary to apply itself to realize drifts free of dredging to realize beautiful fishing and to take pretty trouts!
