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:
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 beeBombus nevadensis,Half-black bumble beeB. vagans and the Eastern common bumble beeB. 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
Please reference the Embedded Range Maps page to better interpret # of observations per ecoregion.
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.
Nevada bumble bee, Bombus nevadensis
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.
Please reference the Embedded Range Maps page to better interpret # of observations per ecoregion.
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.
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..
Van dyke bumble bee,Bombus vandykei, photo by Lisa Robinson
I (DJ) have many fond memories associated with this species. First and foremost, I got the photo (below) and learned this species on a multi-day trip into Stehekin, NCNP to do a NPS sponsored bio-blitz with some of the rockstars of the native bee world: Jamie Strange, H. Ikerd, Terry Griswold and Chris Looney, to name drop a few. What a nice introduction to some amazing people and fun evenings around the campfire getting to know each other.
van Dyke bumble bee, Bombus vandykei
Second, the encounter documented above also shows an important reason why native bees in general, and bumble bees in particular, are the best pollinators for the money–from the perspective of the plant. It demonstrates the foraging behavior of constancy.
The general way that constancy works is that a bumble bee leaves her nest colony for the first time as a worker and stumbles across a flower that offers the needed resources: pollen and nectar.
Not really knowing what she is doing, she figures out how to get her reward. Once she figures it out she looks for a similar flower (same plant species) and is able to figure out even faster how to extract the goods and move on. Now she is efficient with this flower type.
At that point she hones in on every flower of that plant species that still has resources to offer (if the flower has just been visited, the nectar is probably gone and will need to refill over some period of time) until she is fully loaded and goes back to the colony to unload, or runs out of untapped flowers of that species. At that point, if her load is not full, she will look for another flower type and repeat the process.
This behavior, going to the same flower type time again and again is called constancy. The reason why it is so important to the plant species involved is that this greatly increases the probability that the pollen will be spread to many other plantsof the same species, resulting in successful pollination and increasing the “percent seed set” for the fertilized flower. Win-win for both plant and bee.
Please reference the Embedded Range Maps page to better interpret # of observations per ecoregion.
Field guides on bumble bees do a good job show the possible range of color combinations a given species may exhibit across its’ entire range. Trying to condense that into a visual that shows the full spectrum is challenging.
I say that because when I compare the individuals in these photos with the color schema’s shown in Bumble Bees of the Western United States, there are some inconsistencies.
These photos show that T1 sometimes shows yellow, not always black. The field guide shows the rear of the thorax (scutellum) to be black where these photos show some yellow present.
This is a good example of two different lessons. First, bee coloration is variable and may not align exactly with the examples in the book. Different than with most birds, for example.
Second, because color is variable, depending on the species, absolute identifications from photos may not be possible. Photographs rarely capture taxonomic level details like cheek shape. A collected specimen can be keyed out later as a voucher specimen of what was photographed. This should rarely be needed as a good working knowledge of our common species is relatively easy to acquire.
van Dyke bumble bee, B. vandykei
Field ID Tips
A primary field mark to distinguish the van Dyke bumble from others is that the van Dyke shows T3 with yellow.
van Dyke bumble bee can be confused with Two form bumble bee mainly because they are fairly similar is size and both striped black and white/yellow. At least, I have been confused and assumed B. bifarius because bifarius is much more common. Part of the learning curve.
The van Dyke bumble has yellow on T3. T3 is black on the Two form bumble bee. The van Dyke bumble bee also lacks a black inverted triangle on the rear of its thorax.
Based on color patterns, van Dyke bumble bee and yellow forms of California bumble bee are similar. From my experience the van Dyke bumble bee is smaller bodied.
van Dyke bumble bee, B. vandykei
When you look at the pollen gathered on her corbiculum (photo above), you can see it is first one color (orange) and then it shifts to a 2nd color (washed out brown). The bumble started with collecting pollen (and nectar) from first one species, flower after flower (orange pollen). Finally, when it became too difficult to find flowers that had not already been visited, the individual bee switched to a 2nd species of flower and is now demonstrating constancy between flower types–as shown by the change in color of the pollen collected.
van Dyke bumble bee, B. vandykei
One might see the photo above and think Yellow head bumble bee, but this individual shows T2 as black.
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.
Please reference the Embedded Range Maps page to better interpret # of observations per ecoregion.
Yellow head bumble bee, Bombus flavifrons
Notice the cloudy front of thorax (black hairs mixed in).
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.
Yellow head bumble bee, Bombus flavifrons
Yellow head bumble bee, Bombus flavifrons
Yellow head bumble bee, Bombus flavifrons
Photographed on San Juan Island, WA This is a color morph that shows RED (orange). (above)
