Posts Tagged ‘caliginosus’

No red, yes stripes

Friday, July 24th, 2020

This group contains some of my favorite species to encounter in the field. A couple of them can pose a bit of an ID challenge.

Two form bumble bee, B. bifarius
California bumble bee, B. californicus
Yellow-faced bumble bee, B. vosnesenskii
Obscure bumble bee, B. caliginosus
van Dyke bumble bee, B. vandykei

The Two form Bumble shows an inverted black triangle on her scutellum.

T1 = yellow/white
T2 = black
T3 = black
T4 = yellow/white
T5 = black

This form of the California bumble bee looks a lot like the next two species, except this species, the California bumble bee has a BLACK face.

The Yellow-faced bumble bee has a yellow face, scutum and T4. It’s stergites are black.

The Obscure bumble bee has a yellow face, scutum and T4. Stergites S4 and S5 have some white hairs.

On the van Dyke bumble, T3 shows yellow, in contrast to the Two form bumble bee, where T3 is black.

Fogbelt / Obscure bumble bee, Bombus caliginosis

Monday, July 13th, 2020

The Fogbelt bumble bee, Bombus caliginosus, is a species I have found mainly on the southern slopes of the Olympic Mountains. It is not uncommon in that area, but is easily confused with a similar looking species, the Yellow-faced bumble bee, Bombus vosnesenskii.

The common name gives you a sense of it’s preferred habitat.

Please reference the Embedded Range Maps page to better interpret
# of observations per ecoregion.

Field ID tips

The Fogbelt bumble bee has a yellow face with a long cheek, yellow scutum and yellow on T4, with the rest of the bee being black. A key field mark can only be seen with a view of the underside of the abdomen. As seen in the pictures above and below, B. caliginosus shows white hairs on its stergites (underside of abdomen).

Similar Species

The only similar species to the Fogbelt / Obscure bumble bee is the Yellow-faced bumble bee, B. vosnesenskii. They both show yellow face, yellow scutum and yellow T4. A primary way to distinguish between the two is to look on the underside of the abodomen (stergites). Vosnesenskii has a solid black underside. As seen in the picture below, caliginosus show white hairs on its stergites (underside of abdomen). A more subtle field mark is that B. vosnesenskii has relatively even hairs while the Obscure bumble bee has hair a little more unkempt.