I think this is a sphecid wasp in the genus Bembix from looking in my National Wildlife federation insect guide. I was hiking in a sandy wash bajada with carpet blooms of sand verbena and desert gold sunflowers in a spectacular desert flower year. I came upon a small number of these wasps busily buzzing around. I watched one as it excavated its nest hole in the most elaborate fashion. It began an excavation of a hole and a single line of sand thrown backwards from the hole, rapidly backing up from the hole at least 5 to 7 inches all the while flinging the sand backwards in great blasts. It then flew to the hole again and in a parallel line to the side of its first line did the same thing as it worked backwards. It would then do another line from the hole on the other side of the first line and so continued to rapidly excavate the sand in probably 10 or more lines on both sides of the first line from the nest hole. After 15 minutes or so it had excavated a large flat sand pad in front of the hole probably 7 inches long and 5 inches wide. Finally it finished off its nest hole pad by going to either side of the hole and flinging sand backwards, perpendicular to either side of the hole creating an interesting finale to the pad artistry. I was fascinated by this behavior and wondered why did it construct such a huge flat pad in front of the nest hole? It was alot of fun watching this lightning fast fanatic fling sand so commtted to its excavation work in the most artistic and methodical fashion. I needed a faster shutter speed to stop it but only had my automatic compact camera. Anybody know this species? I'll try to add a picture of the finished pad but it may be too big a file.