A stricking piece of labor on the bee hotel, in section I. It is the seal of the nest of a leafcutter bee, probably Willughby’s Leaf-cutter Bee or Patchwork leafcutter bee as I’ve seen these species around the hotels.

Leafcutter bee nest seal
(Megachile sp.)

As the name of this bee family indicates  they cut pieces of leafs which are used to cover the nest walls. Also they cut discs that are used to make walls beteen the nest cells. The entrance is closed by a clog of chewn leaf porridge on which on or more leafs pieces are glued. These leafs are often not glued very tied and will fall of after a few days, which make one wonder what the function is. The leaf in the photo did stick however.