Potter Wasp and Mud Pot Nest - Euodynerus sp.
Order Hymenoptera / Suborder Apocrita / Superfamily Vespoidea -- vespoid wasps/ Family Vespidae -- hornets, paper wasps, potter wasps, yellowjackets 
Live adult wasps photographed in the wild at Winfield Mounds Forest Preserve, Winfield, Illinois, USA. Size: 13mm

The above wasps were mining mud at the west branch of the DuPage River at Winfield IL June 24, 2003.

This female potter wasp has captured and paralyzed a larva with which to provision her mud pot egg chamber.
The egg will hatch and the wasp larva will feed upon the still-living host.

Mud Pot Nest

The Potter wasps construct nests of mud, or nest in burrows, cavities in twigs, or the abandoned nests of other wasps. Most nests are provisioned with caterpillars. Adults are commonly seen on the ground in open areas or at flowers. The clay pot pictured was found inside my patio screen door; I never saw the wasp that constructed it.