Black and yellow mud dauber are usually found June through August.
Their small, mud nests are found under eaves, on porch ceilings, and attached to crevices, cracks, and corners.
The shape of the nest is a key indication of a mud dauber wasp. Female black and yellow mud daubers build a series of short mud tubes measuring about 1” long that are then plastered over with mud to form a smooth mud nest about the size of an apple.
Unless reinhabited by another species, holes in a black and yellow mud dauber nest indicate that the new wasps have emerged from the nest and the nest is inactive.