Mud dauber (sometimes called "dirt dauber," "dirt digger," "dirt dobber," "dirt diver", or "mud wasp") is a name commonly applied to a number of wasps from either the family Sphecildae or Crabronidae that build their nests from mud. Mud daubers, as they belong to different families, are variable in appearance, but most are long, slender wasps about 1-inch (25 mm) in length;. The name refers to the nests that are made by the female wasps, which consist of mud molded into place by the wasp's mandibles. Mud daubers are not aggressive and stings are very uncommon.