...this was during the early days of my insect macro photography. I really had a hard time assessing the size because they were seldom at rest. I mostly see the difference when they are slowed to a stop, as in this photo. What has since been pointed out to me are the ominous looking projections near end of the abdomen that males have. Not stingers, but they seem to be used as a weapon against other insects in "their territory". The male, therefore has a much more armored look. I was pretty sure this was a female when I posted it, but this whole series of shots was an attempt to confirm what I thought.

You were the first one to confirm this, though! Now, I can rest a little easier!

BTW- I was sort of excited to see your A. manicatum shots confirming this bee in the bay area. I don't know how well established they are, or what that means to native species, but they are spectacular bees, don't you think?