Female black and yellow mud daubers paralyze spiders, pack them into the cell with their head until full, lay one egg and seal the cell. Pupation occurs within a cocoon inside the cell. There are two broods with hibernation in the cocoon. Female blue mud daubers take over a mud nest, open a cell by moistening the clay with water and emptying it of spiders and the other wasp egg. They then deposit their own paralyzed spiders, lay their own egg and seal over the cell.
Hosts are mostly black widow spiders.
There is no worker caste and the queens must care for their own young. These wasps are non-aggressive and rarely sting unless touched or caught in clothing. When painting buildings it is often necessary to remove the finger-like mud tubes from places which need to be painted. Nests can be removed with a putty knife and adults killed with a fly swatter, if necessary. Usually it is not necessary to control mud daubers unless their presence is a nuisance.