This is a Hummingbird Moth (Macroglossum stellatarum) feeding on Red Thistle nectar.
A neat scene that got my attention along the South Loop Trail as I have not seen many hummingbird moths this year.
They are known for hovering in place and making an audible humming noise. Not as challenging to photograph as the hummingbirds, but still fun.

Spring Mountains, Nevada. July 2007.