Sheltering from the misting rain

Does anybody know the name of these big moths? It is only the second time that I have seen one, they are as long as my thumb and when they fly , they make a sound as a humming bird.
A grey and very moist day, not liked by my knees, but the plants in the garden look as if they are enjoying it very much.
The snails have discovered my freshly grown lettuce bed, and ate 60 % of all. That does not make them my friends....