Tonopah Desert, Maricopa County, Arizona, USA April 4, 2015 Size: 10mm
This bee is in a Prickly Pear Cactus, Opuntia Engelmannii. I think that this is a male Chimney Bee in the Diadasia australis species group.
These males do not appear to have as much hair as other males that I have seen on BugGuide. I tried to find the best shots of him from all angles.