University of Maryland Extension

Mud Daubers

mud dauber
Black and yellow mud dauber
Photo: O.P. Sharma,

Key Points

  • Mud daubers are dark, often metallic black or blue wasps with long thin waists. Common species are the organ pipe mud daubers, Tropoxylon clavatum (Say) and T. politum (Say), the black and yellow mud dauber, Sceliphron caementarium (Drury), and the blue mud dauber, Chalybion californicum (Saussure).
  • Two closely related groups are the potter wasps and mason wasps.
  • Mud dauber wasps are not aggressive. 
  • They are most often encountered either at puddles where they are collecting mud, or where they are building their mud nests.

    blue mud dauber
    Blue mud dauber
    Photo: Johnny N. Dell,


  • Mud daubers construct "nests" or brood chambers out of mud. Mud daubers' nests are found stuck to the walls of buildings and the sides of equipment. They are also plastered inside electric motor housings of unused machinery.

  • The nests are stocked with spiders paralyzed by a sting. Inside their mud cells, the young wasps eat the spiders. When nests are knocked down (the best method of control), the spiders skins are all that is left to see.

  • Potter wasps, which are predators of caterpillars, construct small mud nests shaped like clay pots with a narrow neck. These are attached individually to sheltered areas such as buildings, twigs or fences.

  • Simply knock down the nest if it is located in an undesirable areaOtherwise, leave  these creatures alone. They are part of the beautiful web of life and add to Maryland’s biodiversity.

Inside of a mud dauber nest with mud dauber larva
and cache of spiders

potter wasp
Potter wasp nests resemble small mud pots

Rev. 2020


Maintained by the IET Department of the College of Agriculture and Natural Resources. © 2020. Web Accessibility

University programs, activities, and facilities are available to all without regard to race, color, sex, gender identity or expression, sexual orientation, marital status, age, national origin, political affiliation, physical or mental disability, religion, protected veteran status, genetic information, personal appearance, or any other legally protected class. If you need a reasonable accommodation to participate in any event or activity, please contact your local University of Maryland Extension Office.