[2][3][4] Bombus californicus is classified as Vulnerable by the IUCN.

[5] In a 2015 study, Bombus californicus was found to be endangered in 62% of surveyed areas.

[6] Bombus californicus can exhibit multiple possible color patterns of yellow and black, as in its sister species Bombus fervidus, and in many areas of geographic overlap, at least a small percentage of individuals of the two species cannot be recognized except by genetic analysis, as each species can sometimes display the color pattern typical of the other.

[1] The "typical" color pattern of female californicus is black with only a single strong yellow band anteriorly on the thorax, and another single yellow band near the apex of the abdomen; males exhibit considerably more variation.

[9] This type of bumblebee pollinates sage,[10] blueberry bushes, red clover,[7] California poppies,[4] and many other species of flowers.