Mason & Potter Wasps

Eumenes fraternus Euodynerus schwarzi Monobia quadridens Ancistrocerus campestris

What are they?

Small to medium-sized, solitary wasps. Many species raise their young in available small holes in woodwork (trees, but also benches, garden furniture etc.), but the English names come from the habit of some species of building small nests out of mud.


Most species are predominantly black, but the position and extent of pale yellow or whitish markings, as well as some differences in shape between the various genera, should allow most species to be identified.

Monobia quadridens

A medium to large mason wasp with a metallic blue sheen on the wings. Females usually build nests in abandoned holes of other bee and wasp species. Sometimes mistaken for Bald-faced Hornet but note the position and extent of white on the abdomen.

Monobia quadridens Monobia quadridens Monobia quadridens

Eumenes fraternus

A medium-sized potter wasp with a distinctive, very narrow, basal section to the abdomen. Females construct small mud nests (pots) which hang from tree twigs and branches. Each nest is furnished with paralized caterpillars and has a single egg laid inside before the entrance is sealed up. The caterpillars serve as food for the growing larva.

Eumenes fraternus Eumenes fraternus Eumenes fraternus
adult with caterpillar prey

Euodynerus schwarzi

A small, solitary wasp that nests in existing holes in woodwork or trees.

Euodynerus schwarzi Euodynerus schwarzi
adult with caterpillar prey

Ancistrocerus campestris

A common species throughout Eastern North America, where it can often be found feeding at goldenrod flowers in late summer. Note the curved line and two dots that form a 'smiley' face on the back.

Ancistrocerus campestris Ancistrocerus campestris Ancistrocerus campestris