Photo #4 is cute; #6 is packing an remarkable haul of white pollen; and in #7  I'm impressed by how you were able to get 3 bees in one tightly-framed view, and all in good focus (especially the middle one). These bees usually move so fast & sporadically that this is very difficult to achieve! Also, the last shot gives a nice feel for what these aggregations look like.

In June 2011 I saw at least three such aggregations in the Santa Lucia Mnts...separated by many miles, and all very large. One covered a good portion of the dirt parking lot for the trailhead to "the Indians"; another spread along about 80 ft of the dirt road a few miles north the gate at the end of the Indians Road; and the third is shown below:

   

I think I still have photos from the first two aggregation somewhere, if so, hopefully I'll post some eventually.

At any rate, they were very fascinating to observe & study.

Moved from Anthophila (Apoidea) - Bees.