Adults can be as large as 1/2 1 plus inches in length. Mud daubers are long and slender in shape and can be a variety of colors including iridescent blue.
Mud daubers select a sheltered site to build their mud tubes. You will most likely see them under eaves, porch ceilings, garages and sheds left open, etc. Nests typically exhibit round holes in them as the wasps emerge. This usually means the nest is old and inactive.
These wasps are solitary, the mud tubes being the nests.