The mud nest is attached to a flat surface in a series of parallel mud tubes of varying length; some constructed like a pipe organ with several tubes in a row. Others may construct a ball-like structure about the size of a lemon. The nest may be a single cell or several cells placed side by side.
Mud daubers may become a nuisance when they construct nests of mud, especially on porches, decks, sheds, eaves, attics, ceilings, walls and under roof overhangs around homes and other structures. They are considered nuisance pests since the nest is not defended and stings are rare. In spite of their appearance, these solitary wasps are not aggressive and controls are rarely needed.
Mud daubers are often seen at the edge of mud puddles collecting mud to construct their nests. The nest chambers are partitioned off with mud and each cell is provisioned with several paralyzed spiders implanted with an egg. After the eggs hatch, the larvae feed on captured spiders, with larvae maturing in about three weeks. The larvae spins a cocoon and over-winters in it.
The female mud dauber paralyzes spiders, pack them into the cell with her head until the nest is full. She lays one egg and seals the cell. The larvae are pale yellowish about 3/4 inch long when fully grown. Pupation occurs within a cocoon inside the cell. There are two broods with hibernation in the cocoon. Host foods are mostly black widow spiders.
Solitary wasps (mud daubers) are very different than the social wasps (hornets, yellowjackets and paper wasps). There is no worker caste and the queens must care for their own young. Mud dauber wasp queens use their sting to paralyze their prey rather than to defend their nests. These wasps are non-aggressive and rarely sting unless touched or caught in clothing.