RED-SHANKED CARDER BEE (Bombus ruderarius): Queen and worker are black with an orange "tail" and orange hairs on the pollen basket on the back "thigh". Males are similar with some yellow hairs on face and thorax. They have a shorter, more squat body than the similar Red-tailed Bumblebee, which has a fox-red tail and black hairs on the pollen basket thigh.
This declining (UK BAP listed) bee nests in old fieldmouse holes.
SHRILL CARDER BEE (Bombus sylvarum): Also called the Knapweed Carder Bee, the name "Shrill" is because the queen makes a shrill buzzing noise in flight.
Light buff or off-white hairs on thorax and abdomen with a black bar on the thorax, two black bars on the abdomen and a pinkish tail not always visible. (Declining UK BAP listed species.)