This is one of the species that seems to be holding its own in terms of numbers.  This worker has a corbicula on its tibia full of a mix of pollen and nectar
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/54563451@N08">USGS Bee Inventory and Monitoring Lab</a> from Beltsville, USA
2013-10-02 15:58
<p><a rel="nofollow" class="external text" href="https://www.flickr.com/photos/usgsbiml/10058868996/">Bombus griseocolis, F, Back, MD, PG County_2013-07-10-16.16.49 ZS PMax</a>
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<ul><li>Uploaded by <a href="//commons.wikimedia.org/wiki/User:Jacopo_Werther" title="User:Jacopo Werther">Jacopo Werther</a></li></ul>