As its name suggests, the Red-tailed Bumblebee has clearly identified reddish-orange hairs on its back. In spring the queen comes out from hibernation and searches for a nest site and then collects nectar and pollen for her offspring - she already carries fertilized eggs.
Red-tailed Bumblebees have very short tongues so prefer flowers which are easy to land on like dandelions, thistles and daisies. Males don't have pollen baskets, so they don't collect pollen.