Posts Tagged ‘Yellow’

Bumbles mainly Yellow

Friday, July 24th, 2020

The Yellow bumble bee, Bombus fervidus is the primary species in this group. Tergites (upper abdomen) segments T1 thru T5 are yellow.

Another species to mention is van Dyle Bumble, B. vandykei. It traditionally falls in the “no red, yes stripes” group, but when I encounter it in the field I am often struck with how much yellow it shows.

Yellow head bumble females, B. flavifrons often show striking bright yellow on T1 and T2.

The yellow form of the California bumble bee, Bombus californicus also shows a lot of yellow.

The Nevada bumble bee has golden yellow on its thorax and T1, T2 and T3.

Other yellow bumbles that are commonly seen on the westside are drones/males of the Yellow head bumble bee B. flavifrons and the Fuzzy-horned bumble bee, B. mixtus.

Notice the rear (3rd) leg (above). Notice it is hairy and relatively round–no corbiculum. Big clue it is a male.

Males often have extra hairs on their upper lip (sound familiar?) giving them the appearance of have a mustache.

Yellow bumble bee, Bombus fervidus

Friday, July 17th, 2020

The Yellow bumble bee, Bombus fervidus, is, in Washington state, very much an east side species.

I have encountered it primarily in SE Washington, in and around the Blue Mountains.

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

Field ID tips

Identification of the Yellow bumble bee, Bombus fervidus, is relatively straight-forward.

  • area between wings (alar) black
  • T1 = yellow
  • T2 = yellow
  • T3 = yellow
  • T4 = yellow
  • T5 = black
  • T6 = black

This is a sturdy bumble and easily noticed as it buzzes through the mountain wildflowers.

Similar Species

Two possible species that could cause confusion are the California bumble bee, B. californicus, and the White-shouldered bumble bee, Bombus appositus.

The yellow form of the California bumble bee will be very similar to the Yellow bumble bee, but shows some black on T2 and T3. There is disagreement about whether the California bumble bee is a subspecies of the Yellow. The two distinct forms come together in the Willamette Valley of Oregon, and you can see some of the mixed patterns that result.

White-shouldered bumble bee, B. appositus, will have distinctly different color shoulders (white) relative to the golden yellow of the abdomen.

The Nevada bumble bee, B. nevadensis shows a lot of yellow on it’s thorax and T1, T2 and T3. T4 and T5 will be black.

Males of several other species are yellow. See example below. Look for the lack of a corbiculum.

Yellow head bumble bee, Bombus flavifrons

Friday, July 17th, 2020

The Yellow head bumble bee, Bombus flavifrons, is a common bumble bee in Thurston county. It is found around the state, but is most commonly encountered on the west side of Washington.

Field ID Tips

The thorax is cloudy.

T1 and T2 are often bright yellow, contrasting with the black rear.

The majority of individuals I have encountered have black on T3, T4 and T5.
In the San Juan Islands, and I hear from a reliable source, around the Mountain Loop highway, T3 may be replaced with red. An example is shown at the bottom of this page.

Similar Species

Similar species include the Central bumble bee, Bombus centralis and the Sitka bumble bee, Bombus sitkensis.

The Central bumble bee has the scutum (front of the thorax) yellow, not cloudy. T3 and T4 will be red, with T5 black.

The Sitka bumble bee will have pale reddish hairs on T 4 and T5. These can be a bit subtle.

Male Yellow head bumble bees

are bright yellow and relatively common in the summer time. They are similar to males of Bombus mixtus.

Look for hairy legs with no pollen attached.