A listener finds mud dauber nests near a bald-faced hornet's nest. Mud dauber wasps are solitary and do not defend their nests, so, they rarely sting humans. Hornets do defend their nests.
The bald-faced hornet, Dolichovespula maculata, is actually a species of yellowjacket and a member of the eusocial, cosmopolitan family Vespidae. It is known by many colloquial names, primarily bald-faced hornet, but also including bald-faced aerial yellowjacket, bald-faced wasp, bald hornet, white-faced hornet, blackjacket, white-tailed hornet, spruce wasp, and bull wasp. As a species of yellowjacket wasp, it is not a true hornet, which are in the genus Vespa. Colonies contain 400 to 700 workers, the largest recorded colony size in its genus, Dolichovespula. It builds a characteristic large hanging paper nest up to 58 centimeters (23 in) in length. Workers aggressively defend their nest by repeatedly stinging invaders.