Mud dauber wasps can reach 1 inch long.
The most common mud daubers are black and yellow or metallic blue. Mud daubers are long wasps with extremely long, thin waists and small abdomens.
Mud daubers are solitary wasps that create nests from blobs of mud. Mud is rolled into a ball, carried to the nest and molded into place with the wasp's mandibles. The wasp creates columns of hollow cells. These wasps do not defend their nests and sting only when they feel directly threatened. Nests are commonly found in eaves, under bridges or in attics of houses.
Mud daubers feed mostly on spiders.
The female mud dauber gathers food, in the form of insect larvae or spiders, stings it to paralyze it, and then places this immobilized prey in the cell. She then lays one egg in each cell, seals the cell with mud, and never returns. The larvae feed on the insects and emerge to start the cycle again.
If the female does not complete a cell before nightfall, she will seal it temporarily and then reopen it in the morning to continue her work.