Pottery Barn

 During the nesting season there are wasps that hail from the the family Sphecidae or Crabronidae who construct their nests from mud. They are known as Mud Daubers.

Most are long and slender and it is the female who builds the nest.  Unlike insect sociopaths such as yellow jacket hornets mud daubers leave you alone unless you really provoke them.  Stings are rare.

Mud daubers are parasitoids.  As they construct the nest they capture and paralyze another insect which is placed into a single cell of the nest.  They lay one egg with the paralyzed prey and seal it up the cavity.  When the egg hatches the wasp larvae consumes the soft parts of the prey insect, pupates with the remains and emerges from this gruesome insect breeding pottery barn as an adult. 

You can find these mud nests is the strangest of places.

Found this in the spray paint section of a shelf in the machine shed.....