The experts at bugguide.net have identified this bee as Bombus perplexus.  I have this bee in the freezer waiting for Rick to id it to confirm the id of the bugguide folks.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/38875278@N08">John Baker</a>
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<a href="//commons.wikimedia.org/wiki/Flickr" class="mw-redirect" title="Flickr">Flickr</a>: <a rel="nofollow" class="external text" href="https://www.flickr.com/photos/38875278@N08/3820958032">Bombus perplexus</a>