Archive for the ‘Red at hind end’ Category

Frigid bumble bee, Bombus frigidus

Monday, July 27th, 2020


Field ID tips

The Frigid bumble bee, Bombus frigidus is a very rarely encountered bumble bee species in Washington. That may be because it is rarely looked for by individuals who go into the high country. That trend seems to be changing. I expect we will be adding additional locations to the map above. It has recently been detected at Harts Pass, by Rich Hatfield.

Key field marks are:

  • the yellow scutum and scutellum,
  • T1 & T2 yellow
  • T3 black (no white hairs)
  • T4 & T5 red/orange
  • high elevation

Similar Species

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

The Frigid bumble bee, Bombus frigidus is easily distinguished from the Forest bumble bee because the red on a frigidus 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 both have T1 and T2 yellow. The High country bumble bee, B. kirbiellus has black on the front half of T3, and 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, and Sitka bumble bee, B. sitkensis are other similar species. A couple of key differences between kirbiellus and mixtus/sitkensis include:

  • Cloudy scutum on mixtus amd sitkensis /yellow on kirbiellus
  • Range (elevation)-one might find B. mixtus and sitkensis pretty high but you will not find frigidus in the lowlands

High country bumble bee, Bombus kirbiellus/balteatus

Monday, July 27th, 2020

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.

Sitka bumble bee, Bombus sitkensis

Sunday, July 19th, 2020

Field ID tips

The thorax area in front of the wings (anterior thorax) is cloudy-a mixture of yellow and black hairs. The rear of the thorax (scutellum) is black. It may show some yellow on the sides as in the picture above.

The two front segments of the abdomen (T1, T2) are yellow. T3 is black. The end of the abdomen (rear of T4, T5, T6) has faint orange/pale hairs.

Similar Species

Two species that should be ruled out are Yellow head bumble bee, B. flavifrons and Fuzzy-horned bumble bee, B. mixtus. In the first instance, the pale hairs at the end of the tail can be missed (flavifrons). In the second, the red/pale hairs of sitkensis are not as prominent as exhibited by most B. mixtus. Mixtus may also show orange on T3.

As seen in the picture above, the anterior thorax is cloudy, T1 and T2 are yellow. T3 is black. T4 may show lots of black also, but will also have pale hairs. The pale hairs on T5 at the end of the abdomen are also visible.

Fuzzy-horned bumble bee, Bombus mixtus

Saturday, July 18th, 2020

I find the Fuzzy-horned bumble bee, Bombus mixtus, to be a common species in Thurston County and much of the west side. It is also found in the north central of the state, and the mountainous areas in eastern Washington.

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

Field ID tips

The relatively bright red rear of the abdomen is a prominent field mark I see on this species. The abdomen feels three (3) toned. Yellow transitioning into black and then into orange.

  • T1 = yellow
  • T2 = yellow with some/ a lot of black possible
  • T3 = black, possibly with some orange
  • T4 = orange
  • T5 = orange

Similar Species

My ID challenge with the Fuzzy-horned bumble bee, B. mixtus is that there are some other, less common species with similar color patterns, such as the Sikta bumble bee, the High country bumble bee and the Frigid bumble bee. Recognizing that an individual with red at the end of the abdomen is NOT mixtus is the larger challenge.

Let me restate: assume you are looking at a Fuzzy-horned bumble bee and then decide if one of the other species may be a better match.

Having said that, Sitka can be ruled out easily because the colors at the end of the abdomen are not as bright and often do not extend up to T3 or even the front portion of T4.

The other two are easily ruled out in most circumstances based on location. Those two species, are high alpine specialists and are not routinely encountered unless extremely lucky or on a targeted mission. A key field mark for separating Bombus mixtus from the other two is color of the scutum. The Fuzzy-horned bumble bee has a cloudy scutum (yellow with black hairs also). The scutum on both the High country bumble bee and the Frigid bumble bee is yellow.