Eremnophila aureonotata ♂.
Size: approx. 20 mm. Photo: 08/06/14, 10 am.

I found these wasps near our pool on a sunny day but really never saw them again. They are very similar to Ammophila species. Adults take nectar and are often found mating on wildflowers. Females dig burrows and provision them with single large caterpillar of moths and skippers.  

bug guide (this photo):