red -tailed Bumblebees

[Guinnessman1974]

Hello, I'm enquiring as to why there are some red-tailed bumblebees which appear completely black all over the body, and others which are black but have a yellow stripe above their head as well?

[Matt Smith]

Bombus lapidarius females (queens and workers) are black with a red tail.

Males of this species have the red tail and a yellow collar band on the front of the thorax and yellow hairs on the face.