This should be a large cabbage white. The pattern on the underneath of the hindwing is quite prominent.
I know that there are variations here but this intense pattern gets me a little bit puzzled as I haven't found any similar pic in the web.
The sequence shows really well how it uses the proboscis.
For those who don't know you can see quite well in the third pic that the proboscis typically has two parts that together form a tube.
When I went to my kitchen today I just found another male mayfly sitting close to this exuvia.
It flew away as I approached it, trying to get both, insect and exuvia on one pic.
I don't know if that was a nymph or a subimago. If it was a nymph I would be totally puzzled as the next small pond is more than 20 m away in my neighbours garden. Much more choices to moult between that and my kitchen window.
And please be tolerant about the cleanliness of my kitchen window.
We have a lot of pine pollen in the air right now. (damned sharp marco lens )