The Mason Wasp

Common Name:
Mason & Potter Wasps
Scientific Name:


These wasps get their common name due to the fact that they make their nest of mud or clay in the form of a ceramic-like pot or jug. In the urban setting, they are occasional nuisance pests. Various species are found throughout the United States.


Adults about 3/8-3/4" (10-20 mm) long. Color black with yellow or white markings. Mandibles elongate, knifelike. Pronotum in lateral view almost triangular, extending to tegulae (structure at base of front wing) or nearly so. Middle tibia with 1 apical spur.


  1. Yellowjackets and hornets (subfamily Vespinae) have middle tibia with 2 apical spurs.

  2. Paper wasps (subfamily Polistinae) have middle tibia with 2apical spurs, hind wing with a small jugal lobe (lobe on rear near body).

  3. Other vespid wasps (Vespidae) have middle tibia with 2 apical spurs, with clubbed antennae, or with long jugal lobe.


  1. Eumenes fraternus Say. Length about 1/2-5/8" (13-17 mm); color black with yellow markings on thorax and abdomen; wings smoky with violet iridescence; abdominal lst segment very narrow, elongated; make potlike clay nest; found in Minnesota, Nebraska, Kansas, Oklahoma, Texas, and eastward to Atlantic coast.

  2. Eumenes iturbide pedalis Fox. Length about 1/2" (13-14 mm); color black with bright yellow markings on thorax and abdomen, with apices of femora, tibiae, and tarsi dull red, wings smoky; abdominal I st segment very narrow, elongated; found throughout western states, Canada, and Mexico.


These are solitary wasps, they are not social and do not live in colonies. These wasps make their pot-like nest or mud nest and then lay a single egg suspended from a wall by a slender filament in the empty nest. They then provision the nest with I- 12 caterpillars or beetle larvae which were paralyzed with their sting, and then sea[ the nest. These wasps are not aggressive and rarely sting people. They do not defend their nests.


Pofter wasps of the genus Eumenes build little clay pots for their nests which are usually attached to twigs but may be attached to window frames or pane dividers. The pots are globular with a narrow neck which has an expanded rim, resembling miniature clay pots or jugs. Members of other genera of this group are not nearly as elaborate with the nest structures, some building merely mud cells. For example, Pachodynerus erynnis (Lapeletier) makes mud nests under siding boards of buildings and will use old mud dauber nests.