Old Mill site in Westwood, Lassen County, California, USA July 27, 2010
Could this possibly be a nest of Sceliphron caementarium, the yellow & black mud dauber wasp? This mud nest was on a spindly mustard species plant in full all day sunshine. Usually I see mud dauber nest in dark shaded areas, so this one has me a bit puzzled. Any ID help or comments appreciated - Thanks!