Unknown bee

mysterybee.JPG

There was an unknown bee (of which I will try to submit a photo on the forum site) that visited one flower 13 minutes after I began observing this morning. It chased away a carpenter bee that landed a couple minutes later. The unknown bee was on the flower until the time I stopped observing, chasing away another bee which I was not able to identify before it landed.
The Gaura lindheimerii that is planted with flowers not a foot from the sunflowers I observe is frequented by honeybees but not one advances to the sunflowers.
Kit Harris
Seattle
(kitharris11)