Habits

Mud daubers are rarely aggressive. They are also the main predator of the black and brown widow spiders. Black-and-yellow mud-dauber build a simple, one-cell, urn-shaped nest that is attached to crevices, cracks and corners. Each nest contains one egg. Usually, they clump several nests together and plaster more mud over them. Blue mud-daubers frequently appropriate old nests of black-and-yellow mud-daubers. They carry water to them and recondition them for their own purposes. The two species commonly occupy the same barns, porches, or other nest sites. Adults of both sexes frequently drink flower nectar. To capture a spider, the wasp grabs it and stings it into submission. The venom from the sting does not kill the spider, but paralyzes and preserves it so it can be transported and stored in the nest cell until consumed by the larva.