Bumble Bees of Washington State

As part of our quest to document all the bumble bee species found in Washington state the team of folks behind this website, David Jennings, Lisa Robinson and Don Rolfs established a state record for the High country bumble bee, Bombus kirbiellus.

In the summer of 2018 David organized an expedition to one of Washington’s high alpine regions, Horseshoe Pass. While in the high country Don netted and collected a bumble bee. We could not easily confirm it’s identity in the field, so it was collected. That bee was subsequently mounted and identified by Lisa. She keyed it out to be Bombus kirbiellus, better known as the High country bumble bee. Until we made this find, there had been no verifiable evidence of this species in Washington state.

Lisa reached out to Rich Hatfield, of the Xerces Society and he helped get our suspicions confirmed by having her identification collaborated by Dr. Paul H Williams at the Natural History Museum, London UK, a worldwide expert on the species.

Teamwork for the win!

Last year (2019), based on our finding, Rich Hatfield visited the site and wrote up his findings here: https://www.xerces.org/blog/bombus-kirbiellus . That would have been a fun trip to be on!

And in reading his article I learned something very useful! The preferred food plant of kirbiellus. Red paintbrush is an easy flower to spot on the landscape!

Again, teamwork for the win!

Field ID tips

The High county bumble bee, Bombus kirbiellus, is as the name suggests a high elevation specialist. There are only a few places high enough with enough resources available for kirbiellus in Washington. The species is much more common in the high alpine country of Colorado up into Montana.

The scutum and scutellum are both yellow, with a black band between the wings. T1 and T2 are yellow, T3 is black with some white hairs in a line, T4 and T5 show orange or red.

Similar Species

The High country bumble bee may be found in association with two other high alpine specialists: Forest bumble bee, Bombus sylvicola and the Frigid bumble bee, Bombus frigidus. All three show red on the abdomen.

The High country bumble bee is easily distinguished from the Forest bumble bee because the red on a kirbiellus is at the end of the abdomen while the red on a sylvicola is on T2 and T3.

It is more of a challenge to visually separate the High country bumble bee from the Frigid bumble bee. They have T1 and T2 yellow. B. kirbiellus has black on the front half of T3, and some yellow on the rear portion of T3. T4 and T5 are orange. Visually, this puts a break (yellow) between the black and red segments. This is in contrast with the Frigid bumble bee where black and red meet directly with no yellow line of separation.

Fuzzy-horned bumble bee, B. mixtus, is another similar species. A couple of key differences between kirbiellus and mixtus include:

• Cloudy anterior thorax (scutum) on mixtus/yellow on kirbiellus
• No yellow break between black and red on lower abdomen (mixtus)

As can be seen below, the front of the thorax is yellow, not cloudy. T1 and T2 are yellow. There is a narrow yellow band breaking up the black/red interface on lower tergites.