Bombus with red tail...species?

Bombus with red tail...species?

Observation - Bombus with red tail...species?. Description: On clover. Not feeding, but completely torpid 'til I started trying to get a closer look, then sluggish wander over the clover head

On clover. Not feeding, but completely torpid 'til I started trying to get a closer look, then sluggish wander over the clover head