University of Maryland Extension

Mud Daubers

mud dauber

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.

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. 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.

Mud dauber wasps are not aggressive and are much less likely to sting than yellowjackets, hornets or paper wasps. They are most often encountered either at puddles where they are collecting mud, or where they are building their mud or dirt cells. Simply knock down the nest if it is located in an undesirable area.

Photo Gallery

blue mud dauber
Blue mud dauber.
Inside of a mud dauber nest with mud dauber larva and cache of spiders.
potter wasp
Potter wasp nests resemble small mud pots.
mud dauber
Mud dauber wasp.
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