Posts Tagged ‘Bombus’

Black tail bumble bee, Bombus melanopygus

Friday, July 17th, 2020

The Black tail bumble bee, Bombus melanopygus, can be encountered in many areas around Washington state: Lowlands like Tumwater on the west side, in the mountains and over across the top of the state and beyond.

When I first started taking pictures of bumbles this species was one of the first I submitted to Bumble Bee Watch. It was also the species that taught me the bumble bee term “cloudy“. Cloudy is the term to describe bumble patterns that have a mixture of black and yellow hairs. On the Black tail bumble bee, the area in front of the wings (scutum) and behind the head is such a mixture of black and yellow. And on the Black tail bumble that cloudiness is very obvious.

Field ID tips

Abdomen pattern is similar in many respects to the Hunt bumble bee, with the big difference at T4.

The Black tail bumble bee

  • Anterior thorax = cloudy (area in front of wings)
  • T1 = yellow
  • T2 = orange
  • T3 = orange
  • T4 = black with some white hairs
  • T5 = black

T4 is black with some white hairs rather than cloudy because the white hairs are in a distinctive line rather than mixed in among the black hairs.

Similar Species

Species that could cause confusion include:

My experience has been that the Black tail bumble bee is pretty distinctive most of the time, leading to confident field identification.

Common eastern bumble, Bombus impatiens

Friday, July 17th, 2020

As might be surmised by the common name, this species is not native to Washington state or the west coast of North America. Fertilized queens of this species can be commercially purchased.

Tomato plants require “buzz” pollination to maximize their yields. Bumble bees can buzz pollinate, honeybees can’t. For this reason greenhouse growers of tomatoes in British Columbia purchased impatiens queens and raised them in the tomato greenhouses. Some queens escaped and got established in the wild in British Columia. The BC population is expanding and has now been detected in Washington state.

It was just three springs back (2017) that Chris Looney and I documented their presence at Peace Arch International Park, on the Canadian border in Whatcom County, WA. Just this summer (2020) I heard that Bombus impatiens had been detected as far south as King County.

The Common eastern bumble bee currently is restricted to areas west of the mountains with the current (but spreading) population centered near Blaine but now documented as far south as King County. It is not expected to expand into the east side, based on some preliminary “suitable range” analysis done by the excellent team of invasive species entomologists at the Washington state Department of Agriculture. Their modeling suggests impatiens may rapidly spread south through western Washington and into Oregon and California.

Keep your eyes peeled. New county record for your list!

Field ID tips

The Common eastern bumble bee abdomen shows a color pattern of:

T1 yellow
T2 black
T3 black
T4 black
T5 black

Similar species

The Common eastern bumble bee is the only species of bumble bee with a black end of abdomen in Washington state that has:

T1 = yellow/white
T2 = black

Suckley cuckoo bumble, Bombus suckleyi

Friday, July 17th, 2020

I have never seen Bombus suckleyi in the wild. I have grave concerns that I never will. Suckley cuckoo bumble bees seemed to prefer the Western bumble bee, Bombus occidentalis. When occidentalis populations crashed, the preferred target species was no longer available to suckleyi.

Predator/prey ratios suggest a smaller population of suckleyi relative to their occidentalist hosts. Suckleyi numbers probably also plummeted, but their population base level had never been estimated so we have no baseline. What we do have is years of increased bumble bee sampling and very few detections of suckleyi since the late 1990s.

If you think you see one, please get good pictures but give serious consideration to NOT COLLECTING IT. Any individual you encounter is a sexually active one. As cuckoos, there are no workers, only queens and drones. At the current population level we need to help all survivors bee successful.

Looking at the color forms for Suckleyi shown in Bumble Bees of the Western United States, all forms of the Suckley bumble bee have a solid yellow T4. That easily separates it from the Indiscriminate cuckoo bumble bee.

Also, male B. suckleyi are all or mainly yellow. Other cuckoo males are not. So if you see a yellow cuckoo you have something special! Get that picture!

The key distinguishing photographically useful feature for separating B. suckleyi from B. insularis and B. fervidus, according to the key in Bumble Bees of the Western United States, by Koch, et al, 2012, is the color of the hairs on the back of the head (Occiput). I have used this in a key, with a handlens, but may be a challenge with just a camera photo.

If the hairs on the occiput are predominantly black it is B. suckleyi.

Both B. flavidus and B. insularis have mainly yellows hairs on the back of their heads. This is important to remember, as far as capturing the key elements needed for photographic identification. Make that shot!

But please, do not collect it!

Indiscriminate cuckoo, Bombus insularis

Friday, July 17th, 2020

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

Field ID tips

We have three species of cuckoo bumbles in Washington state.

Out of the three cuckoo queens, within Washington, only the Indiscriminate cuckoo bumble bee will show a black notch on T4.

Similar Species

At least in Washington, Fernald cuckoo bumble bees B. fernaldae and Indiscriminate cuckoo bumble bee. B. insularis are somewhat easy to distinguish between. As seen in the picture above and below, the Indiscriminate cuckoo has black up the center of tergites T3, T4 and T5 that break up the yellow bands. The Fernald cuckoo bumble bee will have a continuous yellow band on T4 (no black interruption).

The Suckley cuckoo bumblee bee queen also has a solid yellow T4, so the presence of black on T4 is a strong indicator what you have is Bombus insularis. The key distinguishing feature for separating the Indiscriminate cuckoo bumble bee, B. insularis from Suckley cuckoo bumble bee, B. suckleyi, according to the key in Bumble Bees of the Western United States, by Koch, et al, 2012, is the color of the hairs on the back of the head (Occiput). If the hairs on the back of the head are predominantly black it is B. suckleyi.

Both B. flavidus / fernaldae and B. insularis have mainly yellows hairs on the back of their heads. This is important to remember, as far as capturing the key elements needed for photographic identification.

Fernald cuckoo bumble, Bombus flavidus/fernaldae

Friday, July 17th, 2020

Field ID tips

The Fernald cuckoo bumble has a continuous yellow band on T4 (no black interruption).

  • T1 = black
  • T2 = black
  • T3 = black
  • T4 = yellow ( insularis, would show a black area in the center)
  • T5 = black (drones may show some orange or pale hairs)

Similar Species

We have three species of cuckoo bumbles in Washington state.

The Fernald cuckoo bumble bee can be distinguished from the Indiscriminate cuckoo bumble bee because the Indiscriminate bumble has a yellow face and a black notch on T4 while the Fernald cuckoo has a black face and a solid yellow T4

The Fernald cuckoo bumble bee, in the west, is a dark bumble. T3 is black. If T1 is yellow or cloudy, then this is not a reliable field mark.

In the Suckley cuckoo bumble bee, T3 is yellow with a black notch. In the case of B. suckleyi, T1 is always black on a queen. So, if T1 and T3 are black, it is most likely a Fernald cuckoo. If T1 is black and T3 shows some yellow, it may well be a Suckley cuckoo bumble bee. If T1 is cloudy, not black or yellow, it suggests Fernald not Suckley.

The key distinguishing feature for separating B. flavidus from B. suckleyi, the Suckley bumble bee, according to the key in Bumble Bees of the Western United States, by Koch, et al, 2012, is the color of the hairs on the back of the head (Occiput). If the hairs on the back of the head are predominantly black it is B. suckleyi. Bombus fernaldae has mainly yellows hairs on the back of the head. This is important to remember, as far as capturing the key elements needed for photographic identification. Make that shot!

Morrison bumble bee, Bombus morrisoni

Friday, July 17th, 2020

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

The Morrison bumble bee, Bombus morrisoni is very rare in Washington state. There is evidence that the range of B morrisoni’s has been strongly contracting over the last decade or so. There is at least one population of morrisoni remaining in Washington and we hope we can locate others. Similar to what is being seen in Oregon, bumble bees in central Washington seem to be utilizing the urban areas. This may be climate change related, in that it has been so hot and dry many fewer nectar and pollen resources are available in the native landscapes so the urban centers with planted mints and other pollinator plants offer a greater diversity of flowering resources, throughout the full season.

If you encounter a suspected morrisoni in the field, please get good pictures. A positive ID can be made just from photographs for this species, so it would be better to use a non-lethal approach to documenting any individuals you encounter.

Field ID tips

This is a good sized bumble bee, similar to the Nevada bumble bee.

The Morrison bumble bee has a yellow scutum, alar and scutellum

T1 & T2 are yellow. T3 is mainly yellow but may show some black on the sides.

It has a short cheek.

Similar Species

The Nevada bumble bee is the most similar species. It will show a black dot between the wings and T3 will be all yellow. Relative to the Morrison bumble, nevadensis has a long cheek and therefor a very different face shape.

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.

Brown-belted Bumble bee, Bombus griseocollis

Friday, July 17th, 2020

The Brown-belted bumble bee is very much an east side species. It is not that partial to mountainous areas either, more often found in drier lowland areas. I have picked it up near the Canadian border near Sinlaheiken WMA, on a USFWS Milkweed field that is grown for monarch butterflies. That area is very hot and dry, so it fits within the expected habitat preferences.

Field ID tips

From an identification perspective, this species is relatively easy, with just a possible couple of gotcha’s. The worker is distinctive, with a yellow thorax (small to medium spot between the wings), a yellow T1 and a brown T2. T3 thru T6 are all black

Queens, which fly early in the season and again as summer wanes, have a slightly different appearance. T2 is not brown, instead it is similar in color to T1, but with black on each side. See picture above.

  • Thorax yellow with very small to medium black spot
  • T1 = yellow
  • T2 = yellow with black on edges for queen
    T2 = brown for workers
  • T3 = black
  • T4 = black
  • T5 = black

Similar Species

Similar species include the Nevada bumble bee Bombus nevadensis, Half-black bumble bee B. vagans and the Eastern common bumble bee B. impatiens.

The Nevada bumble bee has a yellow T3 and a distinctive thorax spot.

Half-black bumble bee is generally smaller and has a more delicate feel. The two species feel very dissimilar in body shape and behavior. Once you have identified one, when you encounter the other species it will feel like a very different species.

The Common eastern bumble bee currently is restricted to areas west of the mountains with the current (but spreading) population documented as far south as King County. It is not expected to expand into the east side, based on some preliminary “suitable range” analysis done by the excellent team of entomologists at the Washington state Department of Agriculture. The Common eastern bumble bee has a black T2

Nevada bumble bee, Bombus nevadensis

Friday, July 17th, 2020

The Nevada bumble bee, Bombus nevadensis, may well be our largest bumble bee in Washington state. Notice in the picture above its size relative to a native Iris. When I give talks I describe it as being “as large as my thumb”. That may be a bit of an exaggeration, but it is definitely a distinct presence when present.

Field ID tips

The Nevada bumble bee is identified by its larger size, the golden thorax with a black spot in the center, and T1 thru T3 a similar golden brown to the thorax. In some places, T1 may show some black (as in the photo below) but in general T1 is golden/yellow.

Similar Species

Similar species include Brown-belted bumble bee, Bombus griseocollis and the Morrison bumble bee, Bombus morrisoni.

The Brown belted bumble bee has brown on T2 or if yellow (queen) has black on the edges of the yellow on T2. T3 is black.

Morrison bumble bee lacks a black dot on the center of the abdomen. It also shows some yellow on T3. Relative to the long cheek of nevadensis, morrisoni has a short cheek.. If in doubt, look at the shape of the face. Hand lens can be handy. Once you have seen them both, you should feel confident in distinguishing between them.

Nevada bumble bee is an east side species. There are a few records on the west side, but it is not regularly seen there (that I am aware). I found it at the Turnbull NWR on a couple of separate occasions.

Half-black bumble bee, Bombus vagans

Friday, July 17th, 2020

The Half-black bumble bee, Bombus vagans, is an east side species in Washington state. While it is considered common across its range, it is a species that I do not encounter on a regular basis when bumbling around the east side of Washington state. When I do find one, it makes it a better field day for sure!

I have detected them in and around Davenport/Reardon, east of Spokane. Based on the limited number of detections shown on the map below, it has never been an easily found species in Washington state.

Having said that, I recently heard and saw video from Chris Loggers up in the Colville area of bushes swarming with B. vagans. Just goes to show: location, location, location!

In a talk by Dr Lincoln Best, he analyzed available Oregan Bumble Bee Atlas data and had few detections of B. vagans relative to many other species. If you see this species please report it to Bumble Bee Watch, iNaturalist or other citizen science documenting sites,

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

This species is a good example of how much we are learning about bumble bees in Washington state. When the maps above were generated in 2016 they represented the best information easily available for bumbles in Washington state. Fast forward to 2020, where Chris Loggers, in the greater Colville area of the state sent us videos of bushes with well over 100 individual vagans foraging. A nice documented range extension!

Field ID tips

The Half-black bumble bee, Bombus vagans, is a small to medium sized eastside species in Washington. It is a smaller bee relative to the Nevada bumble bee and the Brown-belted bumble bee. The hind end of it’s abdomen is black, and T1 & T2 are yellow. The thorax is predominantly yellow also, usually with a black dot in the alar region. Look for a lump on its face where it might have a nose. I heard this tip from Lincoln Best during his recent (Jan 2021) talk on bumble bees in Oregon.

Similar Species

Similar species include Yellow head bumble bee, Bombus flavifrons and the Common eastern bumble bee, Bombus impatiens.

The Yellow head bumble bee has T1 and T2 yellow (sometimes with some black), but it’s thorax is much cloudier (black hairs mixed in with the yellow hairs). The Half-black bumble bee has the same color yellow on it’s thorax as it has on T1 and T2. The dark spot on the center of the thorax is also more pronounced on the Half-black bumble.

The Common eastern bumble bee is restricted to the west side of the state, so the two species do not overlap. The Common eastern bumble bee has a black T2. The T2 on the Half-black bumble bee is yellow..