Potter's Wasp

Attached to the lanky branch of a plumbago (Ceratostigma plumbaginoides) that inhabits our yard are three marble-sized mud “vases” or “pots”, as they’re sometimes called. The architect of these tiny works of art is the female potter’s wasp, specifically Eumenes fraternus. It has a jet-black body with ivory-colored markings located on the abdomen and thorax. They are also known as mason wasps and provide natural control of caterpillars and beetles larvae that can be detrimental to the plants in your garden. These “solitary” wasps feed on plant nectar and can sting, but are not as aggressive as paper wasps, which will vigorously defend their nest.
In Frank E. Lutz’s “Fieldbook of Insects”, published in 1918, he states that “This is an extensive family (of wasps) and, from an economic standpoint, of great importance to our farmers and fruit-growers, very few of whom know anything at all of the great benefit they are deriving every year from these brightly marked wasps. Their prey on destructive Lepidopterous and Coleopterous larvae, of which they must destroy many thousands every year."

The female constructs the nest by collecting a drop of water and then mixes it with dirt to form a ball. Her saliva is also added to the mix which is believed to add strength to the mixture. Each mud vase or “brood cell” is provisioned with captured and paralyzed caterpillars that are still alive, but in a “zombie-like” state. A single egg is then laid in the narrow-necked jar of mud alongside the prey and then mama wasp seals it up. As the bee larvae inside develops it feeds on the provisioned caterpillar (or caterpillars) until it further develops to the stage where it then wraps itself in a silky cocoon that eventually hardens. Once a fully developed wasp, it eats it way out of its cocoon and mud incubator as seen by the exit hole in the photo.