A strange Bee moth, Melittia sp. from the forest

 This strange Sesiid moth resembles more like a wasp or bumble bee than a moth in flight and can be seen doing "aerial puddling" on damp pebbles. 

As can be seen clearly on this picture, the two forelegs hold on while the moth probe the damp pebble for minerals while the rapid humming bird-like flight keeps it afloat.