You've heard the expression, "wasp waist," in reference to someone's tiny waist?

Well, all you need do is look at the waist of the mud dauber wasp, Sceliphron caementarium, and you'll see where that expression originated.

The pedicel (waist) is about twice as long as the rest of the abdomen, according to BugGuide.net.

This black and yellow wasp is striking in color, and unforgettable in silhouette.

We found this mud dauber wasp (as identified by native pollinator specialist Robbin Thorp, emeritus professor of entomology) on the UC Davis campus near Briggs Hall (home of the  Department of Entomology and Nematology). It was just after a light rain.

The adult females collect mud for their nests, thus the name, "mud dauber." Each "Mama Wasp" will build a nest of some 25 cylindrical cells at a sheltered location, such as in a barn or shed, under a bridge, or on a rock ledge. She will lay one egg per cell, provision it with a spider for the larva to consume, and seal it with mud.

And just like honey bees, the adults nectar flowers. They are reportedly especially fond of parsnip and water parsnip.

And spiders.