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Discover Life
138 kinds match

Bombus affinis  [popup] female queen
Bombus affinis  [popup] female worker
Bombus affinis  [popup] male
Bombus appositus  [popup] female queen
Bombus appositus  [popup] female worker
Bombus appositus  [popup] male
Bombus ashtoni  [popup] female
Bombus ashtoni  [popup] male
Bombus auricomus  [popup] female queen
Bombus auricomus  [popup] male
Bombus auricomus  [popup] female worker
Bombus balteatus  [popup] female queen
Bombus balteatus  [popup] female worker
Bombus balteatus  [popup] male
Bombus bifarius  [popup] female queen
Bombus bifarius  [popup] female worker
Bombus bifarius  [popup] male
Bombus bimaculatus  [popup] female queen
Bombus bimaculatus  [popup] female worker
Bombus bimaculatus  [popup] male
Bombus borealis  [popup] female queen
Bombus borealis  [popup] female worker
Bombus borealis  [popup] male
Bombus californicus  [popup] female queen
Bombus californicus  [popup] female worker
Bombus californicus  [popup] male
Bombus caliginosus  [popup] female queen
Bombus caliginosus  [popup] female worker
Bombus caliginosus  [popup] male
Bombus centralis  [popup] female queen
Bombus centralis  [popup] female worker
Bombus centralis  [popup] male
Bombus citrinus  [popup] female
Bombus citrinus  [popup] male
Bombus cockerelli  [popup] female
Bombus crotchii  [popup] female queen
Bombus crotchii  [popup] female worker
Bombus crotchii  [popup] male
Bombus distinguendus  [popup] female queen
Bombus distinguendus  [popup] female worker
Bombus distinguendus  [popup] male
Bombus fernaldae  [popup] female
Bombus fernaldae  [popup] male
Bombus fervidus  [popup] female queen
Bombus fervidus  [popup] female worker
Bombus fervidus  [popup] male
Bombus flavifrons  [popup] female queen
Bombus flavifrons  [popup] female worker
Bombus flavifrons  [popup] male
Bombus franklini  [popup] female queen
Bombus franklini  [popup] female worker
Bombus franklini  [popup] male
Bombus fraternus  [popup] female queen
Bombus fraternus  [popup] female worker
Bombus fraternus  [popup] male
Bombus frigidus  [popup] female queen
Bombus frigidus  [popup] female worker
Bombus frigidus  [popup] male
Bombus griseocollis  [popup] female queen
Bombus griseocollis  [popup] female worker
Bombus griseocollis  [popup] male
Bombus huntii  [popup] female queen
Bombus huntii  [popup] female worker
Bombus huntii  [popup] male
Bombus hyperboreus  [popup] female
Bombus hyperboreus  [popup] male
Bombus impatiens  [popup] female queen
Bombus impatiens  [popup] female worker
Bombus impatiens  [popup] male
Bombus insularis  [popup] female
Bombus insularis  [popup] male
Bombus jonellus  [popup] female queen
Bombus jonellus  [popup] female worker
Bombus jonellus  [popup] male
Bombus melanopygus  [popup] female worker
Bombus melanopygus  [popup] male
Bombus melanopygus  [popup] female queen
Bombus mixtus  [popup] female queen
Bombus mixtus  [popup] female worker
Bombus mixtus  [popup] male
Bombus moderatus  [popup] female queen
Bombus moderatus  [popup] female worker
Bombus moderatus  [popup] male
Bombus morrisoni  [popup] female queen
Bombus morrisoni  [popup] female worker
Bombus morrisoni  [popup] male
Bombus neoboreus  [popup] female queen
Bombus neoboreus  [popup] female worker
Bombus neoboreus  [popup] male
Bombus nevadensis  [popup] female queen
Bombus nevadensis  [popup] female worker
Bombus nevadensis  [popup] male
Bombus occidentalis  [popup] female queen
Bombus occidentalis  [popup] female worker
Bombus occidentalis  [popup] male
Bombus pensylvanicus  [popup] female queen
Bombus pensylvanicus  [popup] female worker
Bombus pensylvanicus  [popup] male
Bombus perplexus  [popup] female queen
Bombus perplexus  [popup] female worker
Bombus perplexus  [popup] male
Bombus polaris  [popup] female queen
Bombus polaris  [popup] female worker
Bombus polaris  [popup] male
Bombus rufocinctus  [popup] female queen
Bombus rufocinctus  [popup] female worker
Bombus rufocinctus  [popup] male
Bombus sandersoni  [popup] female Queen
Bombus sandersoni  [popup] female worker
Bombus sandersoni  [popup] male
Bombus sitkensis  [popup] female queen
Bombus sitkensis  [popup] female worker
Bombus sitkensis  [popup] male
Bombus sonorus  [popup] female queen
Bombus sonorus  [popup] female worker
Bombus sonorus  [popup] male
Bombus suckleyi  [popup] female
Bombus suckleyi  [popup] male
Bombus sylvicola  [popup] female queen
Bombus sylvicola  [popup] female worker
Bombus sylvicola  [popup] male
Bombus ternarius  [popup] female queen
Bombus ternarius  [popup] female worker
Bombus ternarius  [popup] male
Bombus terricola  [popup] female queen
Bombus terricola  [popup] female worker
Bombus terricola  [popup] male
Bombus vagans  [popup] female queen
Bombus vagans  [popup] female worker
Bombus vagans  [popup] male
Bombus vandykei  [popup] female queen
Bombus vandykei  [popup] female worker
Bombus vandykei  [popup] male
Bombus variabilis  [popup] female
Bombus variabilis  [popup] male
Bombus vosnesenskii  [popup] female queen
Bombus vosnesenskii  [popup] female worker
Bombus vosnesenskii  [popup] male


REMAINING (number with state)
ANSWER THIS FIRST! The Western portion of the guide is usable with caution, let us know if you have problems resolving any species
 2. Click here for guide for all species including western species (138)
 1. EASTERN - Click here for completed and well tested guide to eastern species (77)
Abdomen, T1, hair color, not counting the hairs present on the anterior portion of the segment that faces the propodeum
 All yellow or off-white (105)
 Light and dark hairs mixed or in patches (46)
 All black (39)
 With strong rust, brown, orange, red HIGHLIGHTS or all orange (21)
Abdomen, T2, hair color
 All yellow or off-white (100)
 Light and dark hairs mixed or in patches (59)
 With strong rust, brown, orange, red HIGHLIGHTS or all orange (44)
 All black (40)
Abdomen, T3, hair color
 All black (87)
 All yellow or off-white (61)
 Light and dark hairs mixed or in patches (59)
 With strong rust, brown, orange, red HIGHLIGHTS or all orange (45)
Abdomen, T4, hair color
 All black (87)
 Light and dark hairs mixed or in patches (73)
 All yellow or off-white (69)
 With strong rust, brown, orange, red HIGHLIGHTS or all orange (49)
 All PURE WHITE, NOT light yellow (8)
Abdomen, T5, hair color
 All black (108)
 Light and dark hairs mixed or in patches (63)
 All yellow or off-white (46)
 With strong rust, brown, orange, red HIGHLIGHTS or all orange (29)
 All PURE WHITE, NOT light yellow (10)
B. bimaculatus, B. griseocollis, B. impatiens
 B. bimaculatus - Ocelli inline with tops of eyes - T2 with yellow patch of hair in center which usually does not reach the rim, black to either side of yellow patch - T2 can look just like that of a yellowish B. griseocollis -T2 segment beneath hairs under high magnification appears shiny and light reflective, and to be composed of many slight indents - Hair USUALLY mostly yellow above ocelli (3)
 B. griseocollis - Eyes of male somewhat bulging and ocelli clearly below imaginary line going across tops of eyes - Ocelli of female slightly below level of eyes, sometimes difficult to discern - T2 with hair varying from dark brown to yellowish in center, often occupying most of the segment, some black hair is present on the rim and usually on the far sides - T2 can also look exactly like that of B. bimaculatus - T2 segment beneath hairs under high magnification appears dull and non-light reflective, and to be composed of many tiny bumps - Hair above ocelli USUALLY mostly black (3)
 B. impatiens - Never has anything but black on T2 with a few specimens showing a couple light colored hairs - T2 segment beneath hairs under high magnification appears shiny and light reflective, and to be composed of many slight indents (3)
B. centralis vs. B. flavifrons
 B. centralis - Abdominal segment, T3 and T4 hair color completely or a mix of YELLOW, GOLD, OR ORANGE with no black hairs mixed in - scutum, hair color of anterior area, with exclusively or almost exclusively yellow hairs, although a few black hairs may be found intermixed with the dominant yellow hairs at the lateral edges, if so then the density of black hairs is clearly lower medially than laterally - scutellum, hair color, ranging from exclusively yellow to mixed yellow and black, if the latter then almost always with the black hairs restricted to the center of the scutellum and not mixed throughout all hair on the scutellum (2)
 B. flavifrons - Abdominal segment, T3 and T4 hair color often DARK but sometimes with extensive yellow or orange, however, even dark specimens have at least a few YELLOW OR ORANGE HAIRS ON THE APICAL RIM of the segment, if appearing to have entirely orange hairs then almost always with some black laterally on T3 or T4, note that ANY black hair here will suffice - scutum, hair color in anterior area, always with mixed yellow and black hairs, almost always with an equal density of black hairs throughout, if uneven then only slightly more dense laterally and with black hairs still clearly present medially - scutellum, hair color, highly variable, although the orange form of B. flavifrons seems to always have a significant amount of black hairs intermixed with the yellow hairs of the scutellum, most often with long black hairs present throughout and not restricted to the middle (2)
 B. centralis – Abdomen, T3 and T4 segment hair color ORANGE often bright orange – T5 hair color BLACK or often ORANGE (1)
 B. flavifrons – Abdomen, T3 and T4 segment hair color YELLOW, with T4 sometime half yellow and half black – T5 hair color always BLACK (1)
B. cockerelli vs others
 Others - All other species (137)
 B. cockerelli - Found only in a tiny portion of New Mexico near Cloudcroft and Rio Ruidosa - Note that the male has not be found (1)
B. rufocinctus vs selected other species
 Others - Not as above, although it would be wise to compare possible rufocinctus specimens to long series of positively identified rufocinctus from the same general area in order to account for variation - Malar space is often the most reliable way to initially determine if a specimen IS NOT rufocinctus, any specimens with equal or greater malar spaces in comparison to the basal width of the mandible are very unlikely to be rufocinctus (28)
 B. rufocinctus - Head, malar space, the distance between the very bottom of eye and the mid-point of the attachment of the mandible always much shorter than the width of the base of the mandible, often appearing to be half that distance - Head, hair patch below antennal sockets, hair often but not always all black, if yellow hair is present then they are shorter, more sparsely distributed, and usually significantly more branched than the surrounding black hairs - Head, shortest distance between the lateral ocelli and the compound eye, usually equal to approximately 2-2.4 ocellar diameters in workers, slightly shorter in queens, closer to 1.6-2 ocellar diameters - Head, ocelli height in relation to the top of the compound eyes, slightly below the imaginary line that runs across the top of the eyes, but this is not a reliable character - Propodeum, surface texture, requires HIGH MAGNIFICATION, surface marked with very fine patterning which acts to diminish the integument s luster, this being most evident on the posterior, lateral faces of the propodeum found outside of the basal triangular enclosure - Abdomen, dorsal color patterning, females are tricky to identify because of the EXTREME variability of the abdominal colors, some individuals having a great deal of red on T2-4 while others have none or may exhibit such coloration only on a subset of these tergites, segments can be any combination of orange, yellow, or black, often intermixed on an individual segment, colors may vary even within a colony - Abdomen, T2, surface texture, requires HIGH MAGNIFICATION, surface marked with very fine patterning which acts to diminish the integument s luster, appearing either matte or only very slightly reflective, not distinctly smooth and shiny, punctures - Males, shortest distance between the lateral ocelli and the compound eye, of the 4 species with ocelli well below the tops of the eyes this species has lateral ocelli are 3 quarters to 1 ocelli width from the edge of the eye while the other species ocelli are almost touching the eye (3)
Female, B. affinis vs. B. griseocollis
 B. affinis – Facial hair color ALL BLACK with no specimens showing yellow hairs – Thorax, scutum hair color YELLOW WITH CENTRAL PATCH OF BLACK hair – Abdominal T2 hair color all YELLOW WITH HINTS or patches of BROWN, RED, or ORANGE – Primarily found EAST of the Rocky Mountains with specimens now extremely rare following a population collapse (2)
 B. griseocollis – Facial hair color above antennae all BLACK with significant amounts of SHORTER YELLOW HAIRS inter-mixed – Thorax, scutum hair VERY DENSE and YELLOW with a small often hard to spot patch of black hairs in the center – Abdominal T2 hair color ranges from mostly black with a small yellow patch in the middle of the segment to all yellow, or, more commonly, black at the base grading longitudinally to a band of yellow, grading to brown, and finishing along the rim with with black – Found throughout the U.S. and into Canada (2)
Female, B. appositus vs. B. frigidus vs. B. mixtus
 B. Appositus – Head, hair color PALE YELLOW and DENSE in the queen, normal in the worker but with scattered black hairs– Thorax, scutellum hair color usually ORANGE or orange-brown, but with some specimens hair color yellow instead – Abdominal T2 hair color YELLOWISH ORANGE to yellowish orange-brown – T3 hair color YELLOWISH ORANGE to yellowish orange-brown on tergites yellow is often restricted to along the rims of the segments (2)
 B. frigidus – Head, hair color above antennae BLACK – Thorax, scutellum hair color YELLOW – Abdominal T2 hair color YELLOW – T3 hair color all or mostly BLACK (2)
 B. mixtus – Head, hair color above antennae YELLOW MIXED WITH SOME LONGER BLACK HAIRS – Thorax, scutellum hair color YELLOW or ORANGISH usually mixed with SOME LONGER BLACK HAIRS – Abdominal T2 hair color varies from YELLOW to ORANGE in the middle of the segment, with most specimens showing BLACK or darker colored hairs on the sides – T3 often all or mostly BLACK with yellow hairs along the apical rim, but some specimens can be all orange-yellow with either no black or only a narrow band along the base (2)
Female, B. appositus vs. B. sylvicola
 B. appositus – Head, space between mandible and base of eye DISTINCTLY LONG compared to width – Thorax, scutellum hair ORANGE to orange-brown to sometimes yellow – Abdominal T1 through T5 YELLOWISH ORANGE to yellowish orange-brown, yellow hairs often restricted to along the rim (2)
 B. sylvicola – Head, space between mandible and base of eye roughly equal to width of base of mandible – Thorax, scutellum hair color YELLOW with a wedge of black hairs in the center – Abdominal T1 hair color LIGHT – T2 and T3 hair color with extensive BRIGHT ORANGE though in some individuals the orange is faded to a pale orange – T4 and T5 hair color LIGHT (2)
Female, B. ashtoni vs. B. suckleyi
 B. ashtoni - Abdomen, S6, massive, angular, projecting ridges, one on both lateral edges, their peaks about one-third of the way down from the tip, the outer face of the ridge at its peak is concave, while the inner face is CONVEX - Abdomen, T4, Hairs, usually ENTIRELY pale yellow with hairs in center of segment trending to white - Thorax, Mesepisternum, Hairs, Upper ONE-THIRD, yellow remaining black (1)
 B. suckleyi - Abdomen, S6, massive, angular, projecting ridges, one on both lateral edges, their peaks about one-third of the way down from the tip, the outer face of the ridge at its peak is concave, as well as the inner - Abdomen, T4, Hairs, yellow on sides with BLACK in center and often across the base - Thorax, Mesepisternum, Hairs, Upper TWO-THIRDS, yellow remaining black, sometimes entirely yellow (1)
Female, B. ashtoni vs. B. variabilis
 B. ashtoni – Head, hair color above ocelli BLACK – Abdominal T3, T4, and T5 with SIGNIFICANT AMOUNTS OF YELLOW HAIR (1)
 B. variabilis – Head, hair color above ocelli YELLOW – Abdominal T3, T4, and T5 hair color completely or almost COMPLETELY BLACK (1)
Female, B. auricomus vs. B. pensylvanicus
 B. auricomus - Ocelli without a doubt set well below the imaginary line that runs between the tops of the compound eyes - Scutellum usually lined along the rim with LONG YELLOW hairs intermixed with the usually long black ones - T1 usually all black hairs (2)
 B. pensylvanicus - Ocelli set on only slightly below the imaginary line that runs between the tops of the compound eyes, queens often set about 1 ocelli diameter below - Scutellum usually ALL BLACK but usually has short branched yellow hairs intermixed with the long black ones along the rim - T1 almost always mixed yellow and black hairs, the exact pattern and amounts varying greatly (2)
Female, B. balteatus vs B. frigidus
 B. frigidus - Space between the very bottom of the eye and the mid-point of the attachment of the mandible about the same length as that of the base of the mandible - Hair behind ocelli long, simple, and primarily yellow with some long black hairs interspersed - T6 with very short light colored hairs in the middle of the segment (2)
 Others - All females that have short spaces between the eye and mandible, hair completely yellow on scutellum, mesepisternum, and very clearly patterned abdominal segments T3-5, with the exception of B. mixtus and B. sylvicola whose ranges are to the north in the tundra and taiga, each hairs on each segment being either solely black or yellow - Males are as described under B. rufocinctus (2)
Female, B. balteatus vs. mixtus vs. neoboreus
 B. balteatus – Head, hair color above antennae ALL BLACK or black with patch of yellow in the middle – Abdominal T3 hair color BLACK, with some specimens showing a tiny bit of yellow on the edges of the segment – T4 and T5 hair color usually with ORANGE highlights – T4 usually with black hairs at the base and very rarely the entire segment is black, more commonly the orange highlights appear weak and the light colored hairs appear simply as yellow - Overall hair appearance LONG (2)
 B. mixtus – Head, hair color above antennae YELLOW MIXED WITH SOME LONGER BLACK HAIRS – Thorax, scutellum hair color YELLOW or ORANGISH usually mixed with SOME LONGER BLACK HAIRS – Abdominal T2 hair color varies from YELLOW to ORANGE in the middle of the segment, with most specimens showing BLACK or darker colored hairs on the sides – T3 often all or mostly BLACK with yellow hairs along the apical rim, but some specimens can be all orange-yellow with either no black or only a narrow band along the base – T4 and T5 hair color usually extensively ORANGE, orange-yellow, or yellow – Overall hair appearance normal for a bumblebee (2)
 B. neoboreus – Head, hair color above antennae ALL BLACK – Abdomen T3 hair color YELLOW with at times scattered black hairs – T4 and T5 hair color BLACK – Overall hair appearance LONG (1)
Female, B. bifarius vs. B. fervidus
 B. bifarius - Hair on face above and below antennae generally LIGHTER with some individuals showing mix of light and dark hair - Hair directly behind ocelli LIGHT or showing mix of light and dark hair – Hair on abdomen generally DARKER some individuals exhibiting distinct ORANGE coloring with some individuals showing only yellow hair – Posterior apical angle of the basitarsus on the middle leg often more or less ROUNDED or INDISTINCT although often this is difficult to determine without moving or removing hairs (2)
 B. fervidus - Hair on face generally DARKER above and below antennae with some individuals showing a mix of both light and dark hair and hair directly behind ocelli BLACK or DARK – Hair on abdomen lighter and more yellow never showing any orange coloration - Posterior apical angle of the basitarsus on the middle leg often distinctly POINTED or SHARPLY ANGLED (2)
Female, B. bifarius vs. B. huntii
 B. bifarius – Scutellum generally with fairly distinct V-SHAPED NOTCH or line of black hair or space of no hair dividing the yellow or orange hair into two lateral patches – Coloration of abdominal hair can be highly variable and encompass patterns of a number of other species, making it best to have a long string of known specimens properly compare and identify (2)
 B. huntii - Scutellum without V-SHAPED NOTCH of black hair or space of no hair centrally extending to posterior border, though there may be some black hair in the center of the segment adjacent to the scutum – Hair coloring on abdominal segments T1 thru T5 are consistently and distinctly the same with T1 hairs all yellowish and mixed with a tiny bit of darker hairs, T2 and T3 hairs all very orange colored, T4 hairs all yellow, and T5 hairs completely black on all specimens with no variances in this color scheme (2)
Female, B. bifarius vs. B. occidentalis
 B. bifarius – Scutellum generally with fairly distinct V-SHAPED NOTCH or line of black hair or space of no hair dividing the yellow or orange hair into two lateral patches – No specimens with all black hair on scutellum – Most specimens with YELLOW on one or all of T1, T2, and T3, with no specimens with all black hair on all three abdominal segments (2)
 B. occidentalis - Scutellum if extensively yellow GENERALLY not separated into two lateral patches of yellow, plenty of exceptions, one race has hairs entirely or nearly entirely black on scutellum - T1 always black, T2 usually either all black or with only a narrow boarder of yellow on the apical rim - T3 varies from all black to all yellow (2)
Female, B. bifarius vs. B. sonorus
 B. bifarius – Some specimens with all LIGHT or yellow facial hair - Hair on face above and below antennae generally YELLOW or dark mixed with significant amounts of light or yellow – Hair directly behind ocelli LIGHT or dark mixed with significant amounts of light – Scutellum generally with fairly distinct V-SHAPED NOTCH or line of black hair or space with no hair dividing the yellow or orange hair on the segment into two lateral patches – Posterior apical angle of the basitarsus on the middle leg often more or less ROUNDED or INDISTINCT although often this is difficult to determine without moving or removing hairs (2)
 B. sonorus – Facial hair entirely dark-– Scutellum without a central V-SHAPED NOTCH of black hair or space without hair extending from the apical border to posterior rim - Posterior apical angle of the basitarsus on the middle leg distinctly POINTED or SHARPLY ANGLED (2)
Female, B. bimaculatus vs. B. sandersoni
 B. bimaculatus – Head, malar space clearly longer than width of base of mandible, with a very few specimens showing a malar space that is about equal – Abdominal hair color on T2 is normally YELLOW or light colored in the basal portion of the center of the segment and usually presents itself as a rectangle of yellow surrounded by black hairs on the sides and along the rim, the amount of yellow can vary, but in almost all cases there is significant amounts of black along the sides - In direct comparison, the black hairs on the scutum are largely restricted to the center of the scutum creating only a small patch of black amidst a largely yellow-haired scutum (2)
 B. sandersoni – Head, malar space varies between about the same as the width of the base of mandible to longer – Abdominal hair color on T2 segment is always COMPLETELY YELLOW or light colored with no black hairs on sides of T2 segment, some specimens may show black hairs mixed with light in the middle of the T2 segment - Diagnostic is the presence of pale yellow to off-white on T5 but this can vary from completely pale to completely black, usually there is at least a little yellow on the far sides, and at times there is yellow on the far sides of T4 - In direct comparison, the black hairs on the scutum take up much of the posterior half of the scutum with yellow hairs simply bordering the junction with the scutellum and near the tegulae, scattered black hairs occur in these yellow areas including in the anterior edge of the scutum near the head (2)
Female, B. caliginosus vs. B. vandykei
 B. caliginosus – Abdominal T3 segment hair color BLACK – T4 segment hair color entirely YELLOW or with yellow along the apical rim – Abdominal sternites 3 and 4 hair color YELLOW apically – Sternites 2 and 5 hair color BLACK apically – Very hard to tell apart from B. vandykei and requires very close inspection of tergite and sternite hair coloring (2)
 B. vandykei – Abdominal T3 segment hair color YELLOW at least along the apical rim – T4 segment BLACK with scattered yellow hairs at times along the apical rim and the far sides – Abdominal sternites 2, 3, 4, and 5 hair color yellow apically (1)
Female, B. centralis vs. B. fervidus
 B. centralis – Specimens with all LIGHT or yellow facial hair - Hair on face above and below antennae all YELLOW or a few dark hairs mixed with significant amounts of light or yellow with no specimens showing all dark hairs – Hair directly behind ocelli all LIGHT or a few dark hairs mixed with significant amounts of light with no specimens showing all dark hairs – Abdominal hair color on T5 segment usually LIGHT AND DARK hairs mixed, with some specimens showing all black hairs – Overall hair color on both thorax and abdomen GOLDEN YELLOW or orangish – Generally strictly a western species, only found from of the ROCKY MOUNTAINS and to the WEST (2)
 B. fervidus – Specimens all with DARK or mostly dark facial hair with no specimens showing all light facial hair – Hair on face above and below antennae DARK or mostly dark with a small amount of light hair mixed in, with no specimens showing all light hairs – Hair directly behind ocelli BLACK or dark colored, with no specimens showing all light hairs – Abdominal hair color on T5 segment on all specimens showing BLACK hair, never yellow or orange hairs – Overall hair coloring on the both the thorax and the abdomen bright CANARY YELLOW – Found both EAST AND WEST of the Rocky Mountains (2)
Female, B. citrinus vs. B. suckleyi
 B. citrinus – Facial hair color above antennae always DARK or mostly dark mixed with an insignificant amount of light colored hair – Hair color above ocelli usually LIGHT or mostly light mixed with an insignificant amount of dark colored hair – Center of thorax with ROUNDISH PATCH OF BLACK colored hair or bare patch overlapping basal part of scutum and front part of scutellum – Abdominal T3, T4, and T5 segment hair color always BLACK – Primarily an EASTERN SPECIES found east of the Rocky Mountains, with very few specimens found in western regions (1)
 B. suckleyi – All facial hair dark or BLACK colored with hair above ocelli sometimes mixed with insignificant amounts of light colored hairs – Thorax with BAND OF BLACK colored hair, or bare area, across basal part of scutum from the base of the left wing to the base of the right wing – Scutellum has distinct TRIANGULAR PATCH of slightly darker, or golden, colored yellow hair pointed basally surrounded by lighter yellow colored hair – Abdominal T3 and T4 segment usually have YELLOW colored hairs on the sides or outer edges of the segments with the middle and majority of the segments showing black hairs – Abdominal T5 segment hair color usually entirely BLACK, sometimes with sides or outer edges of segment with yellow colored hairs – Primarily a WESTERN SPECIES found the Rocky Mountains and to the West, with very few specimens found in eastern regions (1)
Female, B. crotchii vs. B. mixtus vs. B. polaris
 B. crotchii – Head, malar space between mid-point of mandible and very bottom of eye compared to width of base of mandible SHORT – Hair color above antennae COMPLETELY BLACK – Thorax, scutellum hair color COMPLETELY BLACK – Abdomen, T1 segment hair color COMPLETELY BLACK- Primarily found in CALIFORNIA and neighboring states (2)
 B. mixtus – Head, malar space between mid-point of mandible and very bottom of eye compared to width of base of mandible SHORT to about equal – Hair color above antennae primarily YELLOW with a few insignificant black hairs mixed in – Thorax, scutellum hair color completely yellow to yellow with scattered black hairs – Abdomen, T1 segment hair color YELLOW – Overall appearance, normal bumblebee hair length – Primarily found from the THE ROCKY MOUNTAINS to the WEST, but with a very few specimens recorded in more eastern parts of North America (2)
 B. polaris – Head, malar space between mid-point of mandible and very bottom of eye compared to width of base of mandible LONG or about equal – Hair color above antennae COMPLETELY BLACK – Thorax, scutellum hair color YELLOW or yellow with a black central wedge of hairs - Abdomen, T1 segment hair color YELLOW – Overall appearance, very long hair length – Primarily found in more northern ranges, with no recorded specimens found south of Canada (2)
Female, B. franklini vs. B. vandykei
 B. franklini – Facial hair color above antennae mix fairly equal mix of LIGHT AND DARK hairs, but with most specimens showing all dark hairs – Hair color above ocelli YELLOW – Thorax hair color on scutum YELLOW with a PATCH OF BLACK or no hair in the middle of the scutum, with the YELLOW hair extending basally past the front wing bases in the shape of an INVERTED U – Abdominal T3 and T4 segments hair color BLACK – Abdominal T5 segment hair color BLACK, with some specimens showing 2 small white or LIGHT COLORED SPOTS on either side of the segment – Very rare and hard to find specimen, thought to be endangered or possibly extinct, with the last documented specimen found in 2006, note that we only had 1 specimen of B. franklini to compare to and used information from http://www.xerces.org/franklins-bumble-bee/ for additional information. (2)
 B. vandykei – Facial hair color YELLOW, both above antennae and above ocelli, with only a few scattered black hairs on the outside edges of the hair patches – Thorax, scutum, hair color YELLOW from head to base of wings and BLACK hair extending basally – Abdominal T3 segment hair color YELLOW at least along the apical rim – T4 segment BLACK with scattered yellow hairs at times along the apical rim and the far sides – Abdominal T5 segment hair color ALL BLACK (2)
Female, B. frigidus vs. B. jonellus vs. B. sylvicola vs. B. mixtus
 B. frigidus - Head, hair color above antennae is BLACK or primarily black - Abdomen, T2 hair color is YELLOW or ORANGISH-TINTED - T3 hair color BLACK and often has YELLOW OF ORANGE HAIRS ON THE BASAL EDGE or the segment (2)
 B. jonellus - Head, hair color above antennae is BLACK or primarily black - Abdomen, T2 hair color is YELLOW, often with black along the apical rim - T3 hair color is BLACK and often has a few WHITE HAIRS ALONG THE APICAL RIM of the segment (2)
 B. mixtus - Head, hair color above antennae is YELLOW or primarily yellow - Abdominal T2 hair color varies from YELLOW to ORANGE in the middle of the segment, with most specimens showing BLACK or darker colored hairs on the sides – T3 often all or mostly BLACK with yellow hairs along the apical rim, but some specimens can be all orange-yellow with either no black or only a narrow band along the base (2)
 B. sylvicola - Head, hair color above antennae varies from YELLOW to primarily yellow - Abdomen, T2 and T3 hair color extensively BRIGHT ORANGE with some specimens showing only a faint orange color to sometimes nearly yellow, often, but not always with no black hairs present (2)
Female, B. frigidus, B. sandersoni, B. vagans
 B. frigidus - Hairs on T4-5 orange or orange-yellow - Always with a strong band of black hairs between the tegula on the scutum - Space from lowest point of eye to mid-point of attachment of mandible roughly equal to width of mandible at base - Face appears squarish (2)
 B. sandersoni - T1-T2 usually entirely yellow, some specimens may show scattered black hairs on T2 - Hair on T4 black, but at times with yellow or off-white hair on the far sides - Hair on T5 can be pale yellow, off-white, black, if appearing all black there are usually a few yellow hairs on the far sides - Space from lowest point of eye to mid-point of attachment of mandible varies from roughly equal to width of mandible at base to longer - Hair above the ocelli is almost always largely black but often with scattered yellow hairs - In direct comparison, the black hairs on the scutum take up much of the posterior half of the scutum with yellow hairs simply bordering the junction with the scutellum and near the tegulae, scattered black hairs occur in these yellow areas including in the anterior edge of the scutum near the head (2)
 B. vagans - Hair on T4-5 always black, except in Newfoundland where the endemic subspecies bolsteri has T5 yellow - Space from lowest point of eye to mid-point of attachment of mandible longer than width of mandible at base - Face appears long, horsey - In direct comparison, the black hairs on the scutum are largely restricted to the center of the scutum creating only a small patch of black amidst a largely yellow-haired scutum, though with scattered black hairs laterally to the tegula - Hairs above the ocelli almost always with extensive amounts of yellow, apparently never all black (2)
Female, B. huntii vs. B. sylvicola vs. B. melanopygus
 B. huntii – Head, malar space between mid-point of mandible and very bottom of eye compared to width of base of mandible SHORT or ABOUT EQUAL – Hair color above antennae COMPLETELY YELLOW to MIXED WITH BLACK– Thorax, scutum hair color YELLOW in front half and BLACK in rear half – Abdomen, T5 segment hair color COMPLETELY BLACK (2)
 B. melanopygus – Head, malar space between mid-point of mandible and very bottom of eye compared to width of base of mandible roughly EQUAL – Hair color above antennae usually appears primarily YELLOW but always has a significant amount of long black hairs intermixed among long yellow hairs and densely packed shorter yellow hairs in northern populations but usually all Yellow in the western ranges of the U.S. – Thorax, scutum, hairs are an intermixing of yellow and black hairs with black hairs predominating near the scutellum and light hair predominating towards the head, southern populations the lower half is usually entirely black and the upper a mix of yellow and black hairs – Abdomen, T5 hair color northern populations PRIMARILY BLACK usually with a few yellow hairs on the outer edges of the segment, southern populations with extensive yellow, black only retained in the central third of the segment (2)
 B. sylvicola – Head, space between mandible and base of eye roughly equal to width of base of mandible – Hair color above antennae BLACK to mixed black and yellow - Thorax, scutum, hair color YELLOW in front half and BLACK in rear half – Abdomen, T5 hair color YELLOW, or PRIMARILY BLACK with a few yellow hairs on the outer edges of the segment (2)
Female, B. melanopygus vs. B. morrisoni vs. B. sonorus
 B. melanopygus – The race of B. melanopygus within the range of these species has hair on the scutum that is black in the lower half and a mix of yellow and scattered black hairs in the upper – Hair color below base of front wing COMPLETELY YELLOW – Abdomen, T2-3 segments hair color BLACK – T5 segment hair color largely yellow with some black hairs (2)
 B. morrisoni – Thorax, scutum hair color YELLOW in front half and BLACK in rear half – Hair color below base of front wing BLACK WITH YELLOW PATCH right at the base – Abdomen, T2 segment hair color YELLOW – T3 hair color YELLOW with almost always a small amount of black on the far sides and along the apical rim (2)
 B. sonorus – Thorax, scutum hair color COMPLETELY YELLOW– Hair color below base of front wing COMPLETELY BLACK – Abdomen, T2 hair color YELLOW – T3 hair color YELLOW (2)
Female, B. mixtus vs B. sitkensis
 B. mixtus - T3 tends to be largely black with a thin border of light hairs along the rim - T4 almost always covered by completely light hairs (2)
 B. sitkensis - T3 tends to be entirely black - T4 tends to be largely black with at times a thin border of light hairs along the rim (2)
Female, B. neoboreus vs. B. polaris
 B. neoboreus – Abdomen, T3 segment hair color primarily YELLOW but almost always with at least some black hairs intermixed – Very difficult to tell apart from B. polaris (2)
 B. polaris – Abdomen, T3 segment hair color largely BLACK, but almost always with extensive yellow intermixed some specimens almost entirely yellow – Very difficult to tell apart from B. neoboreus and best done by comparison with known specimens (2)
Female, B. perplexus vs. B. sandersoni
 B. perplexus – Thorax, scutum hair color COMPLETELY YELLOW – Queens and SOME workers have BLACK HAIRS extending up the mesepisternum from the ventral edge to nearly to the top of the segment, however, many workers are all yellow - In directly comparison the hairs on the thorax and abdomen are LONGER AND NOT AS DENSE (2)
 B. sandersoni – The BLACK HAIRS on the scutum take up much of the posterior half of the scutum with yellow hairs simply bordering the junction with the scutellum and near the tegulae, scattered black hairs occur in these yellow areas including in the anterior edge of the scutum near the head - Hair on mesepisternum always yellow - In direct comparison, the hairs on the abdomen are similar to most other species of bumblebee in length and density (2)
Female, B. rufocinctus vs. B. ternarius
 B. rufocinctus bright form – Thorax, scutum hair color YELLOW with ROUND BLACK PATCH of hair in the middle NOT extending to the base of the wings – Scutellum hair color ALL YELLOW – Abdomen, T5 hair color usually BLACK WITH SIGNIFICANT AMOUNTS OF YELLOW hair (2)
 B. ternarius – Thorax, scutum hair color YELLOW in the FRONT PORTION near the head with a WIDE BAND OF BLACK colored hair extending from wing base to wing base – Scutellum hair color YELLOW with a DISTINCT LINE or TRIANGLE OF BLACK hair pointing toward the abdomen – Abdomen, T5 hair color ALL BLACK (2)
Female, Parasitic Species - Architecture of S6, when viewed from the side with specimen upside down - Note, the pattern of ridges and swellings on S6 is distinct to each species, but difficult to describe
 Highest point occurs approximately HALF-WAY between tip and base - In direct comparison, height is modest to low (4)
 Highest point occurs approximately ONE-THIRD of the way down from the tip - In direct comparison, height is greater, stongly angular and ridge-like (2)
Female, Queen, B. auricomus vs. B. nevadensis
 B. auricomus – Thorax, scutum hair color in FRONT HALF YELLOW and in BACK HALF BLACK – Abdominal T1 hair color BLACK, YELLOW, or MIXED (1)
 B. nevadensis – Thorax, scutum hair color COMPLETELY YELLOW with some specimens showing a small PATCH OF BLACK in the center of the segment – Abdominal T1 hair color YELLOW with no specimens showing black (1)
Female, Queen, B. bimaculatus vs. B. morrisoni
 B. bimaculatus – Thorax, below base of front wing hair color completely LIGHT or yellow continuing all the way down the side of the thorax – Abdomen hair color on T2 usually light or YELLOW IN THE CENTER with dark or BLACK colored hair on both SIDES of the T2 segment, almost never completely yellow – Abdomen hair color on T3 usually ALL BLACK or dark colored, occasionally with a little lighter colored hair in the middle of the segment (1)
 B. morrisoni – Thorax, below base of front wing has small patch of light or yellow colored hair located very close to wing base with the rest of the hair continuing all the way down the side of the thorax BLACK or very dark colored – Abdomen hair color on T2 always COMPLETELY YELLOW or light colored, never black – Abdomen hair color on T3 sometimes completely YELLOW or mostly yellow with some black or dark colored hair on the sides, hair never completely dark or black colored (1)
Female, Queen, B. caliginosus vs. B. vosnesenskii
 B. caliginosus - Head, space between mid-point of attachment of mandible and very bottom of eye compared to width of base of mandible USUALLY LONG, but some specimens show shorter spaces - Very hard to tell apart from B. vosnesenskii, but has a very small distribution and is only found in COASTAL RANGES from northern Washington to southern California (1)
 B. vosnesenskii - Head, space between mid-point of attachment of mandible and very bottom of eye compared to width of base of mandible SHORT - Very hard to tell apart from B. caliginosus, which has a very limited distribution only in the coastal regions from northern Washington to southern California, and if the specimen is found outside of this range it is most likely B. vosnesenskii (1)
Female, Queen, B. centralis vs. B. huntii
 B. centralis – Malar space in comparison to B. huntii is often LONGER - Abdominal hair coloring over all appearance GOLDEN YELLOW, and appears darker directly compared to B. huntii – T1 through T4 hair color can vary from shades of yellow to reddish orange or a mix of yellows and oranges – Abdominal hair coloring of T2 segment in FRESH SPECIMENS is usually YELLOW with only a tinting of orange if at all, and hair color of T4 is usually bright ORANGE (1)
 B. huntii – Malar space in comparison to B. centralis is often SHORTER – Abdominal hair coloring distinct for each tergite segment and with little variance among specimens, and appears lighter and brighter than B. centralis – T1 segment hair coloring YELLOW - T2 and T3 segments distinctly bright ORANGE in appearance but mixed with significant amounts of yellow hairs – T4 segment hair color YELLOW – Abdominal hair coloring of T2 segment in FRESH SPECIMENS is usually ORANGE, and hair color of T4 is usually YELLOW (1)
Female, Queen, B. centralis vs. B. sonorous
 B. centralis – Hair on face above and below antennae all YELLOW or a few dark hairs mixed with significant amounts of light or yellow with no specimens showing all dark hairs – Hair directly behind ocelli all LIGHT or with only a few dark hairs mixed in with no specimens showing all dark hairs – Thorax hair coloring below base of front wing always all LIGHT or sometimes with an insignificant amount of darker hair mixed in –Abdominal hair coloring on T4 segment usually LIGHT or orangish, sometimes mixed with dark or black hair, with no specimens showing all black colored hairs (1)
 B. sonorous – Facial hair entirely dark - Thorax hair coloring below base of front wing usually all DARK with very small PATCH OF LIGHT hair directly adjacent to base of wing and pronotal lobe, with no specimens showing all light hair coloring –Abdominal hair coloring on T4 segment always BLACK, never all light or yellow in color (1)
Female, Queen, B. centralis vs. B. sylvicola vs. B. melanopygus
 B. melanopygus – Facial hair color LIGHT or LIGHT AND DARK MIX – Abdominal T2 hair color BRIGHT ORANGE - T3 hair color BRIGHT – T5 hair color BLACK (2)
 B. centralis – Facial hair color largely LIGHT with only scattered dark hairs, if any at all – Abdominal T2 hair color usually YELLOW with some darker gold – light orange hairs in the middle of the segment – T3 hair color usually the same – T5 hair color DARK with some specimens showing an insignificant amount of light colored hairs (1)
 B. sylvicola – Facial hair color LIGHT or LIGHT AND DARK MIX – Abdominal T2 hair color BRIGHT ORANGE or reddish – T3 hair color BRIGHT ORANGE or reddish – T5 hair color LIGHT with a few specimens showing an insignificant amount of dark hairs mixed in (1)
Female, Queen, B. griseocollis vs. B. morrisoni
 B. griseocollis – Facial hair of most specimens showing all DARK coloring usually with insignificant amounts of yellow hairs mixed in, however some specimens showing equal amounts of light and dark hairs mixed –Thorax hair coloring YELLOW, with distinct CIRCULAR PATCH OF BLACK hair or no hair on the basal center of the scutum – Thorax hair color below base of front wing COMPLETELY YELLOW or light colored – Hair color on T3 and T4 ALL BLACK with no specimens showing yellow or lighter colored hairs – Overall appearance of thorax and abdominal hair is much LESS DENSE than that of B. morrisoni – Found throughout the U.S. and Canada both in the East and West (1)
 B. morrisoni – Hair color above antennae ALL BLACK or, if yellow present, restricted to short hairs – Hair color above ocelli a mix of yellow and black hairs – Thorax hair color, on both the scutum and scutellum, completely YELLOW with no specimens showing circular patch of black or dark hair – Thorax hair color below base of front wing with a PATCH OF YELLOW hair directly adjacent to wing base apically with the rest of the hair COMPLETELY BLACK or dark colored – T3 hair color YELLOW with almost always a small amount of black on the far sides and along the apical rim – Abdominal T4 segment hair color BLACK with most specimens showing some yellow or light colored hair in the middle of the segment apically – Overall appearance of thorax and abdominal hair is much DENSER than that of B. griseocollis – Primarily a western species found from the ROCKY MOUNTAINS to the WEST with eastern specimens uncommon (1)
Female, Queen, B. griseocollis vs. B. perplexus
 B. griseocollis – Facial hair in most specimens ALL BLACK with insignificant amounts of light hair mixed in, however some specimens showing equal amounts of light and dark hairs mixed – Malar space distinctly SHORT, less than the width of the mandible, with no specimens showing longer spaces – Thorax hair coloring YELLOW, with distinct CIRCULAR PATCH OF BLACK hair or no hair on the basal center of the scutum –T1and T2 hair color YELLOW TO REDDISH BROWN or orange, note that sometimes these non-yellow colors are hard to see in specimens that haven’t been cleaned well – T3, T4, and T5 hair color ALL BLACK – Found throughout the U.S. and Canada both in the east and west – Upper edges of lateral ocelli SLIGHTLY BELOW the imaginary line that crosses between the very tops of the compound eyes (1)
 B. perplexus – Hair color above antennae VARIES, with some specimens showing all light, all dark, or a mix of both light and dark hairs – Hair color above ocelli ALL LIGHT with insignificant amounts of dark hairs mixed in – Malar space VARIES between distinctly short, roughly equal, and clearly longer – Thorax hair coloring YELLOW or light, with no distinct circular patch of black or dark colored hair – Abdominal segment T1 and T2 hair color YELLOW or light, with no specimens showing any reddish or orange hairs – Abdominal segments T3, T4, and T5 ALL BLACK – Primarily an eastern species found east of the Rocky Mountains with few specimens found in western U.S., but range commonly extends into the western parts of Canada where species is commonly found – Upper edges of lateral ocelli at the same level as the imaginary line that crosses between the very tops of the compound eyes (1)
Female, Queen, B. griseocollis vs. B. sandersoni
 B. griseocollis – Facial hair color both above antennae and ocelli overall appearance black or dark, but with significant amounts of yellow hairs mixed in – Abdominal segments T1 and T2 hair color YELLOW OR ORANGISH, but note that poorly prepared specimens can appear to be all yellow – T5 hair color COMPLETELY BLACK, with no specimens showing any yellow hairs – Found throughout the U.S. and most of Canada – Upper edges of lateral ocelli SLIGHTLY BELOW the imaginary line that crosses between the very tops of the compound eyes (1)
 B. sandersoni – Facial hair color both above antennae and ocelli overall appearance yellow or light, but with significant amounts of dark hairs mixed in –T1 and T2 hair YELLOW with no specimens showing any red or orangish brown hairs – Abdominal segment T5 hair color YELLOW or black with significant amounts of yellow hairs mixed in – Primarily found in the EASTERN parts of the U.S. and Canada with only a few specimens found scattered in western parts of Canada – Upper edges of lateral ocelli at the same level as the imaginary line that crosses between the very tops of the compound eyes (1)
Female, Queen, B. moderatus vs. B. occidentalis
 B. moderatus – Thorax, scutellum hair color BLACK with no specimens showing any yellow coloring – T2 hair color primarily YELLOW, usually with a hard to notice, very narrow band of black hairs along the apical rim – T3 hair color completely BLACK or almost completely black (1)
 B. occidentalis – Species has 2 different forms – Thorax, scutellum hair color of form 1 YELLOW – T3 hair color for form 1 YELLOW or mostly yellow – Thorax, scutellum hair color of form 2 BLACK –T2 hair color of form 2 completely BLACK – T3 hair color for form 2 completely BLACK (1)
Female, Queen, B. morrisoni vs. B. nevadensis
 B. morrisoni – Facial hair color above ocelli a mix of yellow and black hairs – Thorax scutum hair color COMPLETELY YELLOW and hairs noticeably dense and relatively short – T3 hair color YELLOW with almost always a small amount of black on the far sides and along the apical rim – Primarily found in the WESTERN parts of North America with very few specimens found east of the Rocky Mountains (1)
 B. nevadensis – Facial hair color above ocelli DARK colored in some specimens or an even MIX of light and dark colored hairs – Thorax scutum hair color YELLOW WITH CIRCULAR PATCH OF BLACK or no hair in center – T3 hair color COMPLETELY YELLOW with no specimens showing black hairs on sides – Found throughout U.S. and Canada (1)
Female, Queen, B. morrisoni vs. B. rufocinctus
 B. morrisoni – Thorax, scutum hair color COMPLETELY YELLOW – Hair color below base of front wing BLACK WITH YELLOW PATCH right at the base – Abdomen, T2 segment hair color COMPLETELY YELLOW (1)
 B. rufocinctus – Thorax, scutum hair color YELLOW in front half and BLACK in rear half – Hair color below base of front wing COMPLETELY YELLOW – Abdomen, T2 segment hair color BLACK, ORANGE, or mix of YELLOW AND ORANGE, not completely yellow (1)
Female, Queen, B. morrisoni vs. B. sandersoni
 B. morrisoni – Thorax scutum hair color COMPLETELY YELLOW and thick – Thorax hair color below base of front wing BLACK with PATCH OF YELLOW HAIR at the top of the mesepisternum – T3 hair color YELLOW with almost always a small amount of black on the far sides and along the apical rim – T5 hair color COMPLETELY BLACK – Primarily found in the WESTERN parts of North America with very few specimens found east of the Rocky Mountains (1)
 B. sandersoni – Thorax scutum hair color YELLOW WITH CIRCULAR PATCH OF BLACK or no hair in center – Thorax hair color below base of front wing YELLOW – T3 hair color COMPLETELY BLACK – T5 hair color in most specimens YELLOW AND DARK MIX – Primarily found in the EASTERN parts of North America with very few specimens found from teh Rocky Mountains to the WEST (1)
Female, Queen, B. morrisoni vs. B. sonorous
 B. morrisoni – Facial hair color above ocelli a mix of yellow and black hairs – Thorax scutum hair color COMPLETELY YELLOW – T3 hair color YELLOW with almost always a small amount of black on the far sides and along the apical rim – Primarily found in WESTERN North America with a few specimens found in Northern parts of Mexico (1)
 B. sonorous – Facial hair entirely dark – Thorax scutum hair color in most specimens YELLOW WITH A BAND OF BLACK colored hair running from tegula to tegula – T3 hair color COMPLETELY YELLOW – Primarily found in the SOUTHWESTERN U.S. and throughout Mexico and Central America (1)
Female, Queen, B. morrisoni vs. B. vagans
 B. morrisoni – Thorax hair color below base of front wing BLACK with PATCH OF YELLOW HAIR at the top of the mesepisternum – T3 hair color YELLOW with almost always a small amount of black on the far sides and along the apical rim – Overall appearance of yellow colored hairs GOLDEN YELLOW – Primarily found in WESTERN North America with a few specimens found east of the Rocky Mountains (1)
 B. vagans – Thorax hair color below base of front wing all YELLOW – T3 hair color BLACK – Overall appearance of yellow colored hairs DULL YELLOW or LIGHT YELLOW – Specimens found throughout U.S. and Canada (1)
Female, Queen, B. nevadensis vs. B. sonorous
 B. nevadensis – Facial hair color above ocelli ranges from all DARK to LIGHT AND DARK MIXED – Thorax scutum hair color all YELLOW or all YELLOW WITH A SMALL BLACK PATCH in center – T1 hair color can vary from BLACK TO YELLOW BUT USUALLY IS A MIXTURE – Found throughout North America (1)
 B. sonorous – Facial hair entirely dark – Thorax scutum hair color YELLOW WITH BLACK BAND across the rear running from tegula to tegula – T1 hair color always COMPLETELY YELLOW – Found primarily in the SOUTHWESTERN US and MEXICO (1)
Female, Queen, B. sylvicola vs. B. ternarius
 B. sylvicola – Head, hair color above the antennae PRIMARILY BLACK, but can have a fair amount of scattered yellow hairs – Thorax, scutellum hair color YELLOW with a black wedge of hairs in the center – Abdomen, T5 hair color can be YELLOW or fade to be PRIMARILY BLACK with a few yellow hairs on the outer edges of the segment (1)
 B. ternarius – Head, hair color above the antennae YELLOW often surrounded by a black border – Thorax, scutellum hair color YELLOW WITH DISTINCTIVE LINE OF BLACK or no hair down the center – Abdomen, T5 segment hair color COMPLETELY BLACK (1)
Female, Worker, B. bifarius vs. B. sylvicola vs. B. melanopygus vs. B. rufocinctus
 B. bifarius – Head, malar space between mid-point of mandible and very bottom of eye compared to width of base of mandible SHORT to about equal – Hair color above antennae YELLOW sometimes with scattered long black hairs – Thorax, scutum hair color YELLOW in front half and BLACK in rear half – Scutellum hair color YELLOW WITH DISTINCTIVE LINE OF BLACK or no hair down the center - In comparison to B. melanopygus has fewer scattered long black hairs throughout the upper part of the mesepisternum tricky to tell apart without comparative material (1)
 B. rufocinctus – Head, malar space between mid-point of mandible and very bottom of eye compared to width of base of mandible always distinctly shorter – Head, hair color above the antennae PRIMARILY BLACK or YELLOW AND BLACK MIX – Thorax, scutum hair color YELLOW in front half and BLACK in rear half – Scutellum hair color YELLOW (1)
 B. sylvicola – Head, malar space between mid-point of mandible and very bottom of eye compared to width of base of mandible SHORT – Hair color above antennae BLACK sometimes with an insignificant amount of yellow hair mixed in - Thorax, scutum hair color YELLOW in front half and BLACK in rear half – Scutellum hair color YELLOW (1)
Female, Worker, B. griseocollis vs. B. perplexus
 B. griseocollis – Facial dark in most specimens ALL BLACK with insignificant amounts of light hair mixed in, however some specimens showing equal amounts of light and dark hairs mixed – Malar space distinctly SHORT, with no specimens showing longer spaces – Thorax hair coloring YELLOW, with distinct CIRCULAR PATCH OF BLACK hair or no hair on the basal center of the scutum – Abdominal segment T1and T2 hair color YELLOW TO REDDISH or orange, note in some poorly washed and dried specimens it is difficult to see the non-yellow colors – T3, T4, and T5 hair color ALL BLACK – Found throughout the U.S. and Canada both in the East and West – Upper edges of lateral ocelli SLIGHTLY BELOW the imaginary line that crosses between the very tops of the compound eyes (1)
 B. perplexus – Hair color above antennae VARIES, with some specimens showing all light, all dark, or a mix of both light and dark hairs – Hair color above ocelli ALL LIGHT with insignificant amounts of dark hairs mixed in – Malar space VARIES between distinctly short, roughly equal, and clearly longer – Scutum and scutellum hair all YELLOW or light, with no distinct circular patch of black or dark colored hair – Abdominal segment T1 and T2 hair color YELLOW or light, with no specimens showing reddish or orange hair coloring – T3, T4, and T5 in most specimens showing ALL LIGHT or yellow hairs mixed with an insignificant amount of darker hairs, but with some specimens showing all or mostly dark or black hair color – Primarily an eastern species found east of the Rocky Mountains with few specimens found in western U.S., but range commonly extends into the western parts of Canada – Upper edges of lateral ocelli at the same level as the imaginary line that crosses between the very tops of the compound eyes (1)
Female, Worker, B. jonellus vs. B. sandersoni
 B. jonellus –T1, T2, T3, and T4 hair color in most specimens a MIX of both LIGHT AND DARK colored hairs – Abdominal segment T5 hair color completely LIGHT colored ranging from yellow to white – Primarily found in more northern parts of Canada and into Alaska, as well as throughout Europe, with very few specimens found south of Canada – Difficult to tell apart from B. sandersoni (1)
 B. sandersoni –T1 and T2 hair color distinctly YELLOW with very few specimens showing darker hairs mixed in – Abdominal segment T3 and T4 hair color DISTINCTLY BLACK with no specimens showing any lighter hairs mixed in – Abdominal segment T5 hair color varies from completely BLACK to some specimens showing light or yellow colored hairs on the outer edges of the segment – Primarily found in the EASTERN parts of the U.S. and Canada with only a few specimens found scattered in western parts of Canada and with very few specimens found more than mid -continental Canada – Difficult to tell apart from B. jonellus (1)
Female, Worker, B. moderatus vs. B. occidentalis
 B. moderatus – T2 hair color almost entirely YELLOW or LIGHT COLORED with a often overlooked narrow band of black hairs along the rim – T5 hair color ALWAYS WHITE (1)
 B. nevadensis – T4 and T5 hair color DISTINCTLY DARK with no specimens showing lighter colored hairs – Overall body hair color GOLDEN YELLOW and THICK – Found throughout North America (1)
 B. occidentalis – T2 hair color completely BLACK or mostly black with some specimens showing some yellow or light colored hairs on the sides of the segment or on the basal edge – T5 hair color WHITE , YELLOW, OR LIGHT MIX (1)
 B. perplexus – T4 and T5 hair color LIGHT in some specimens and DARK in other specimens – Overall body hair color PALE or LIGHT YELLOW and THIN – Primarily found EAST OF THE ROCKY MOUNTAINS and in some western parts of Canada (1)
Female, Worker, B. nevadensis vs. B. sonorous
 B. nevadensis – Facial hair color above antennae LIGHT AND DARK MIX – Facial hair color above ocelli LIGHT AND DARK MIX – Thorax scutum hair color all YELLOW or YELLOW WITH BLACK PATCH in center – Thorax hair color below base of front wing YELLOW or mostly yellow – Found throughout North America (1)
 B. sonorous – Facial hair color above antennae ALL DARK – Facial hair color above ocelli ALL DARK – Thorax scutum hair color YELLOW WITH BAND OF BLACK HAIR across center – Thorax hair color below base of front wing BLACK or mostly dark with small patch of lighter colored hair directly apical wing base – Found primarily in the SOUTHWESTERN US and MEXICO (1)
Female, Worker, B. sylvicola vs. B. ternarius
 B. sylvicola – Head, hair color directly above the ocelli YELLOW – Thorax, scutellum hair color YELLOW – Abdomen, T5 hair color YELLOW, or PRIMARILY BLACK with a few yellow hairs on the outer edges of the segment (1)
 B. ternarius – Head, hair color directly above the ocelli BLACK – Thorax, scutellum hair color YELLOW WITH DISTINCTIVE LINE OF BLACK or no hair down the center – Abdomen, T5 segment hair color COMPLETELY BLACK (1)
Female, queen, B. californicus vs. B. centralis
 B. californicus – Specimens all with DARK facial hair with no specimens showing all light facial hair - Hair on face above and below antennae DARK sometimes with insignificant amounts of lighter hairs mixed in - Hair directly behind ocelli BLACK or dark colored – Some specimens with scutellum hair color ALL BLACK - Abdominal hair color on T1 segment in some specimens all BLACK – Posterior apical angle of the basitarsus on the middle leg usually distinctly POINTED or SHARPLY ANGLED (1)
 B. centralis – Hair on face above and below antennae generally YELLOW or with only a few dark hairs mixed in – Hair directly behind ocelli LIGHT or with only a few dark hairs mixed in – Scutellum hair color always LIGHT, yellow, or orange colored, never all black – Abdominal hair color on T1 segment in all specimens COMPLETELY LIGHT, yellow, or orange colored, never all black – Posterior apical angle of the basitarsus on the middle leg often more or less ROUNDED or INDISTINCT although often this is difficult to determine without moving or removing hairs (1)
Female, worker, B. bifarius vs. B. ternarius
 B. bifarius – Some specimens with all LIGHT or yellow facial hair - Hair on face above and below antennae generally YELLOW or dark mixed with significant amounts of light or yellow – Hair directly behind ocelli LIGHT or dark mixed with significant amounts of light – Some specimens with all LIGHT or yellow abdominal hair – Upon very close inspection hair on front of abdominal segment T2 sometimes showing a small number of BLACK hairs - Found primarily from the Rocky Mountains WEST with the Easternmost specimens found in parts of Nebraska – Genetically a sister group of B. ternarius, and very hard to tell apart (2)
 B. ternarius – Specimens all with DARK facial hair with no specimens showing all light facial hair - Hair on face above and below antennae distinctly BLACK sometimes with insignificant amounts of lighter hairs mixed in - Hair directly behind ocelli BLACK or sometimes black with insignificant amounts of lighter hairs mixed in – Specimens all have ORANGE T2 and T3 abdominal hairs with no specimens showing all yellow abdominal hairs – Upon close inspection, hair on base of abdominal segment T2 never showing black hairs – Found primarily EAST of the Rocky Mountains and only documented in the West in the state of Montana - Genetically a closely related sister group of B. bifarius, and very hard to tell apart (2)
Female, worker, B. caliginosus vs. B. vandykei
 B. caliginosus – Abdominal T3 segment hair color BLACK – T4 segment hair color YELLOW – Abdominal sternites 3 and 4 hair color YELLOW apically – Sternites 2 and 5 hair color BLACK apically – Very hard to tell apart from B. vandykei and requires very close inspection of tergite and sternite hair coloring (1)
 B. vandykei – Abdominal T3 segment hair color YELLOW at least along the apical rim – T4 segment BLACK with scattered yellow hairs at times along the apical rim and the far sides – Abdominal sternites 2 through 5 hair color YELLOW along the apical rim - Very hard to tell apart from B. caliginosus and requires very close inspection of tergite and sternite hair coloring (1)
Female, worker, B. franklini vs. B. occidentalis
 B. franklini – Facial hair color above antennae mix fairly equal mix of LIGHT AND DARK hairs, but with most specimens showing all dark hairs – Hair color above ocelli YELLOW – Thorax hair color on scutum YELLOW with a PATCH OF BLACK or no hair in the middle of the scutum, with the YELLOW hair extending basally past the front wing bases in the shape of an INVERTED U – Abdominal segments T1 through T4 hair color BLACK – Abdominal segment T5 hair color ALL BLACK, with some specimens showing 2 small white or LIGHT COLORED SPOTS on either side of the segment – Very rare and hard to find specimen, thought to be endangered or possibly extinct, with the last documented specimen found in 2006, note that we only had 1 specimen of B. franklini to compare to and used information from http://www.xerces.org/franklins-bumble-bee/ for additional information. (1)
 B. occidentalis – Facial hair color COMPLETELY DARK, both above antennae and above ocelli, with no specimens showing light or yellow hairs – Thorax hair color on scutum all YELLOW only up to the base of the front wings with BLACK hair starting at the wing bases and extending basally, with some specimens showing only a band of dark hair at the wing bases with the rest of the scutum yellow – Abdominal segments T1 through T4 hair color HIGHLY VARIABLE ranging from light to black hairs on segments, but with no single specimen showing all black hair on T1, T2, T3, and T4 at the same time – Abdominal segment T5 hair color varies between light yellows and WHITE (1)
Females, parasitic vs non-parasitic queens and workers
 Non-Parasitic, common species, outer part of tibia largely hairless, flat, or concave, and rimmed by long hairs (84)
 Parasitic, rare to uncommon species, hairs on outer face of tibia uniform in density and length throughout, tibia uniformly convex (6)
Head, color of hairs just behind ocelli
 Both light and dark hairs (109)
 Light (101)
 Black (66)
Head, long hairs located just above antennae - Note that there is usually a fuzz of shorter, highly branched hairs that are often yellow, at the base of the longer hairs, these short hairs should be ignored
 Both light and dark hairs (106)
 Black (90)
 Light (70)
Head, ocelli, position relative to imaginary line across tops of eyes
 About right on the line (125)
 Distinctly below (25)
Head, space between mid-point of attachment of mandible and very bottom of eye compared to width of base of mandible
 Clearly longer (90)
 Roughly equal (86)
 Clearly shorter (70)
Male, B. affinis, B. bimaculatus, B. perplexus vs B. vagans
 B. affinis - Space between eye and mandible clearly and often very much shorter than width of base of mandibles - Hair above ocelli around antennae and on cheeks all black or with only a few yellow hairs -Hair on T1-2 yellow or yellow tinged with brown - Hair on T3-6 black - Only a few specimens of the formerly abundant species have been regularly seen since 2002. please report all sightings (1)
 B. bimaculatus - Hair on T1-2 sometimes all yellow, but most often T2 with large patches of black on sides - Hair on T3 can be largely yellow, but always with some black hairs intermixed and usually all black - Hair on T4-6 all black or can also have extensive amounts of yellow mixed in - Face with yellow hairs throughout - Space between bottom of eye and mid-point of attachment of mandible, longer than or equal to width of base of mandible (1)
 B. perplexus - Face hair with large amounts of yellow - Hair on T1-2 all yellow - Hair on T3 all black or with some yellow intermixed - Hair on T4-6 usually black but can have extensive intermixing of yellow hairs - Space between bottom of eye and mid-point of attachment of mandible slightly longer than width of base of mandible (1)
 B. vagans - Hair on T1-2 always yellow - Hair on T3-4 always black - Hair on T5-6 all black or often with small yellow patches on the far sides - Space between bottom of eye and mid-point of attachment to mandible longer than width of base of mandible - Face can be all black or with extensive amounts of yellow (1)
Male, B. appositus vs. B. bifarius vs. B. centralis
 B. appositus – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible DISTINCTLY LONG – Hair color above antennae all yellow but usually with A FEW BLACK HAIRS MIXED IN – Thorax, hair color on rear half of scutum a DISTINCT BAND OF BLACK – Scutellum hair color GOLD or ORANGE – Hind leg, projecting hairs on rear edge of tibia BLACK – Abdomen, segment T2 through T6 hair color GOLDEN never with any black hairs mixed in (1)
 B. bifarius – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible ABOUT EQUAL – Hair color above antennae ALL YELLOW with no black hairs present – Thorax, hair color on rear half of scutum a DISTINCT BAND OF BLACK – Scutellum hair color YELLOW or GOLD – Hind leg, projecting hairs on rear edge of tibia YELLOW – Abdomen, segment T3 hair color gold with a significant amount of DARK BROWN TO BLACK mixed in – T2, T4, T5 and T6 sometimes with a significant amount of DARK BROWN TO BLACK mixed in (1)
 B. centralis – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible DISTINCTLY LONG – Hair color above antennae ALL YELLOW with no black hairs present – Thorax, hair color on rear half of scutum usually has BLACK HAIRS MIXED IN without a distinct band of black – Scutellum hair color YELLOW or GOLD – Hind leg, projecting hairs on rear edge of tibia YELLOW – Abdomen, segment T3, T4, and T5 hair color can be GOLD or ORANGE – T6 hair color DARK BROWN or BLACK (1)
Male, B. appositus vs. B. fervidus vs. B. huntii
 B. appositus – Head, hair color above antennae YELLOW but usually with a FEW BLACK HAIRS MIXED IN of the same length – Hair color behind ocelli YELLOW – Hind leg, long projecting hairs on rear edge of tibia BLACK – Abdomen, segment T2 through T6 hair color GOLD (1)
 B. fervidus – Head, hair color above antennae LONG BLACK HAIRS MIXED WITH SHORT YELLOW hairs – Hair color behind ocelli BLACK – Hind leg, long projecting hairs on rear edge of tibia BLACK – Abdomen, segment T2 through T5 hair color GOLD – T6 hair color GOLD or BLACK (1)
 B. huntii – Head, hair color above antennae YELLOW – Hair color behind ocelli YELLOW – Hind leg, long projecting hairs on rear edge of tibia YELLOW – Abdomen, segment T2 through T4 hair color GOLD or ORANGE – T6 hair color BLACK (1)
Male, B. appositus vs. B. perplexus vs. B. polaris
 B. appositus – Head, hair color above antennae YELLOW but usually with a FEW BLACK HAIRS MIXED IN – Hind leg, long projecting hairs on rear edge of tibia BLACK – Abdomen, segment T4 through T6 hair color GOLD – Found from the Rocky Mountains WEST (1)
 B. perplexus – Head, hair color above antennae YELLOW or MIXED YELLOW AND BLACK – Hind leg, long projecting hairs on rear edge of tibia BLACK – Abdomen, segment T4 and T6 hair color usually BLACK – T5 hair color always BLACK – Found throughout eastern North America and into Western Canada (1)
 B. polaris – Head, hair color above antennae BLACK – Hind leg, long projecting hairs on rear edge of tibia YELLOW – Abdomen, segment T5 and T6 hair color YELLOW – Found throughout Canada (1)
Male, B. appositus vs. B. sonorus vs. B. vandykei
 B. appositus – Head, hair color above antennae YELLOW with a few black hairs mixed in – Thorax, hair color on rear half of scutum a distinct BAND OF BLACK – Hind leg, long projecting hairs on rear edge of tibia BLACK colored – Abdomen, segment T5 hair color GOLD (1)
 B. sonorus – Head, hair color above antennae mostly BLACK LONG HAIRS with some shorter YELLOW HAIRS MIXED IN – Thorax, hair color on rear half of scutum a distinct BAND OF BLACK – Hind leg, long projecting hairs on rear edge of tibia BLACK colored – Abdomen, segment T5 hair color BLACK (1)
 B. vandykei – Head, hair color above antennae YELLOW – Thorax, hair color on rear half of scutum YELLOW with no distinct band of black hairs – Hind leg, long projecting hairs on rear edge of tibia YELLOW colored – Abdomen, segment T5 hair color GOLD (1)
Male, B. ashtoni vs B. insularis
 B. ashtoni - Hair above antennae all black - Side of thorax below where front wing joins with yellow hairs for about a third to a half and the rest black - Hairs on T2 mostly to all black (1)
 B. insularis - Hair above antennae with a small amount of yellow - Sides of thorax below front wings with all yellow hair - Hairs on T2 mostly or completely yellow (1)
Male, B. ashtoni vs. B. fernaldae vs. B. suckleyi
 B. ashtoni – Head, malar space between midpoint of attachment of mandible and bottom of eye compared to width of base of mandible SHORT or sometimes about equal – Hair color behind ocelli BLACK, YELLOW, OR MIX – Thorax, hair color below base of wing a PATCH OF YELLOW with BLACK BELOW – Scutellum hair color YELLOW – Abdomen, T5 segment hair color black with SIGNIFICANT AMOUNTS OF YELLOW ON OUTER EDGES – Genitalia, if visible the ends of the claspers are TRIANGULAR SHAPED – Very hard to tell apart from B. fernaldae and B. suckleyi (1)
 B. fernaldae – Head, malar space between midpoint of attachment of mandible and bottom of eye compared to width of base of mandible LONG, with an occasional specimen being about equal in length – Hair color behind ocelli primarily YELLOW – Thorax, hair color below base of wing YELLOW – Scutellum hair color DARK or YELLOW WITH V- OR U-SHAPED PATCH OF DARK or no hair – Abdomen, T5 segment hair color ALL BLACK with no yellow hairs – Genitalia, if visible the ends of the claspers are THIN AND STICK-LIKE with lobed or ROUNDED TIPS - Very hard to tell apart from B. ashtoni and B. suckleyi (1)
 B. suckleyi – Head, malar space between midpoint of attachment of mandible and bottom of eye compared to width of base of mandible SHORT – Hair color above ocelli YELLOW or MIXED – Thorax, hair color below base of wing YELLOW –Scutellum hair color YELLOW – Abdomen, T5 segment hair color black with SIGNIFICANT AMOUNTS OF YELLOW ON OUTER EDGES – Genitalia, if visible the ends of the claspers are TRIANGULAR SHAPED – Very hard to tell apart from B. fernaldae and B. ashtoni (1)
Male, B. balteatus vs. B. frigidus vs. B. jonellus
 B. balteatus – Head, cheek hair color primarily BLACK – Hair color above antennae ALL BLACK or occasionally with a few insignificant yellow hairs mixed in, hair color between antennal bases yellow – Abdomen, segment T3 hair color BLACK – T4 hair color BLACK or sometimes YELLOW – T5 and T6 YELLOW or ORANGISH – Primarily found from the Rocky Mountains WEST and in more northern regions – Virtually indistinguishable from B. frigidus and B. jonellus (1)
 B. frigidus – Head, cheek hair color primarily BLACK – Hair color above antennae a mix of YELLOW AND BLACK or occasionally all yellow – Abdomen, segment T3 hair color BLACK often with a FRINGE OF YELLOW ON REAR RIM – T4 hair color usually BLACK or sometimes YELLOW – T5 and T6 YELLOW or ORANGISH – Found throughout North America – Virtually indistinguishable from B. balteatus and B. jonellus (1)
 B. jonellus – Head, cheek hair color BLACK or YELLOW – Hair color above antennae a mix of YELLOW AND BLACK – Abdomen, segment T2 ALL YELLOW, occasionally mostly or ALL BLACK – T3 hair color BLACK – T5 and T6 hair color YELLOW or WHITISH – Found in Alaska and northern Canada – Virtually indistinguishable from B. balteatus and B. frigidus (1)
Male, B. balteatus vs. B. mixtus
 B. balteatus – Head, malar space between midpoint of attachment of mandible and bottom of eye compared to width of base of mandible LONG, giving a horsey-like appearance – Hair color directly above antennae BLACK, with the hair between and below the antennae yellow and usually bordered by a few black hairs (1)
 B. mixtus – Head, malar space between midpoint of attachment of mandible and bottom of eye compared to width of base of mandible SHORT or about EQUAL – Hair color above, between, and below antennae YELLOW with an occasional insignificant black hair or two (1)
Male, B. bifarius vs B. californicus
 B. bifarius - Malar space, distance between the mid-point of the mandible s attachment and the bottom of the eye, equal to or slightly longer than the width of the base of the mandible - Head, hair color above antennal sockets, ranging from a mixture of black and yellow hairs throughout to black hairs being present only in the lateral and posterior edges of this hair patch, with yellow always the dominant hair color - Head, hair patch below antennal sockets, hair near-exlusively yellow, if any black hair is present then it is restricted to the lateral edges of this hair patch, hair LONG and DENSE, often completely covering the clypeus - T3 almost always completely black or with a few pale hairs on the far lateral sides - In direct comparison, smaller (1)
 B. californicus - Malar space, distance between the mid-point of the mandible s attachment and the bottom of the eye, clearly longer than the width of the base of the mandible - Head, hair color above antennal sockets, a mixture of black and yellow hairs throughout, most often with black as the dominant hair color in this patch although some specimens seem to exhibit an equal mixture - Head, hair patch below antennal sockets, black and yellow hairs intermixed throughout the hair patch, although yellow is most often still the dominant color, hair SHORT and SPARSE, often leaving clypeus mostly exposed - T3 almost always with significant amounts of yellow hair, usually there is a clear band of yellow hair along the rim with black and yellow hairs intermixed throughout the interior of the segment - In direct comparison, larger (1)
Male, B. bifarius vs. B. flavifrons vs. B. jonellus
 B. bifarius – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible SHORT or about equal – Thorax, hair color of rear half of scutum YELLOW, usually with some black hairs mixed in (1)
 B. flavifrons – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible LONG – Thorax, hair color of rear half of scutum YELLOW (1)
 B. jonellus – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible LONG – Thorax, hair color on rear half of scutum a DISTINCT BAND OF BLACK – Abdomen, segment T5 and T6 hair color often white (1)
Male, B. bifarius vs. B. huntii vs. B. ternarius
 B. bifarius – Abdomen, T2 segment hair color YELLOW in the middle or black and yellow MIX, always with BLACK PATCHES on the SIDES although it may only be a few hairs – T3 hair color BLACK or mostly black, occasionally an equal mix of black and yellow – T4 hair color YELLOW or mostly yellow – T5 hair color ALL YELLOW or yellow with a patch of black in the middle (1)
 B. huntii – Abdomen, T2 and T3 segment hair color BRIGHT ORANGE – T4 hair color YELLOW to ORANGE – T5 hair color YELLOW often with a patch of black in the center, sometimes yellow and black mix (1)
 B. ternarius – Abdomen, T2 and T3 segment hair color ORANGE to GOLDEN – T4 hair color YELLOW, GOLD, or ORANGE – T5 hair color BLACK (1)
Male, B. bifarius vs. B. huntii vs. B. vandykei
 B. bifarius – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible about EQUAL to SHORT – Thorax, hair color on rear half of scutum a DISTINCT BAND OF BLACK hairs – Abdomen, segment T3 hair color dark brown to BLACK, not bright orange (1)
 B. huntii – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible about equal to LONG – Thorax, hair color on rear half of scutum a DISTINCT BAND OF BLACK hairs – Abdomen, segment T3 hair color usually BRIGHT ORANGE, but sometimes yellow (1)
 B. vandykei – Head, malar space, space between mandible and bottom of eye compared to width of base of mandible about equal to LONG – Thorax, hair color on rear half of scutum YELLOW, with no black hairs present – Abdomen, segment T3 hair color YELLOW, not bright orange (1)
Male, B. bifarius vs. B. melanopygus vs. B. mixtus
 B. bifarius – 2 different forms – Form 1, highly variable hair coloration – Head, facial hair color COMPLETELY YELLOW – Thorax, scutum hair color, front half YELLOW, rear half mixed or BLACK – Scutellum hair color YELLOW, sometimes with a strip of black or no hair down the center – Leg, hind tibia hair color YELLOW – Abdomen, T2 segment hair color YELLOW in the middle or black and yellow MIX, always with BLACK PATCHES on the SIDES although it may only be a few hairs – T3 hair color BLACK or mostly black, occasionally an equal mix of black and yellow – T4 hair color YELLOW or mostly yellow – T5 hair color ALL YELLOW or yellow with a patch of black in the middle – T6 hair color BLACK – Form 2 – Head, facial hair color mixed – Thorax, scutum hair color ALL YELLOW – Scutellum hair color YELLOW, sometimes with a strip of black or no hair down the center – Leg, hind tibia hair color BLACK – Abdomen, T2 segment hair color YELLOW in the middle and BLACK on the sides – T3 through T6 hair color BLACK (1)
 B. melanopygus – Head, facial hair color YELLOW and BLACK mix – Thorax, scutum hair color front half YELLOW AND BLACK MIX or primarily yellow, rear half BLACK – Scutellum hair color YELLOW, sometimes with a strip of black or no hair down the center – Leg, hind tibia hair color BLACK, although it can appear yellow in faded museum specimens – Abdomen, T2 and T3 segment hair color BRIGHT ORANGE to reddish – T4 hair color usually a mix of YELLOW and BLACK or primarily yellow – T5 and T6 hair color BLACK or primarily black (1)
 B. mixtus – Head, facial hair color YELLOW – Thorax, scutum hair color front half YELLOW occasionally with a few black hairs mixed in, rear half yellow and black MIX or all BLACK –Scutellum ALL YELLOW – Leg, hind tibia hair color YELLOW – Abdomen, T2 segment hair color YELLOW to orange – T3 hair color ALL BLACK, primarily black mixed with some yellow, or black on front half of segment and yellow on the rear half – T4 through T6 hair color YELLOW to ORANGE (1)
Male, B. bifarius vs. B. sonorus
 B. bifarius – Head, facial hair color YELLOW, occasionally with a few insignificant black hairs mixed in – Thorax, hair color beneath base of front wing YELLOW – Hind leg, long projecting hairs on rear edge of tibia YELLOW colored – Abdomen, segment T3 hair color usually BLACK, but occasionally yellow (1)
 B. sonorus – Head, facial hair color primarily LONG BLACK HAIRS mixed with some SHORT YELLOW hairs – Thorax, hair color beneath base of front wing BLACK – Hind leg, long projecting hairs on rear edge of tibia BLACK colored – Abdomen, segment T3 hair color YELLOW (1)
Male, B. bimaculatus vs. B. jonellus vs. B. mixtus
 B. bimaculatus – Thorax, rear half of scutum hair color all or primarily YELLOW with a FEW BLACK HAIRS MIXED IN – Leg, hind tibia hair color BLACK – Abdomen, segment T2 hair color all YELLOW or YELLOW IN THE CENTER with BLACK ON THE SIDES – T4 hair color can be all BLACK or all YELLOW – Primarily found east of the Rocky Mountains (1)
 B. jonellus – Thorax, rear half of scutum hair color ALL or mostly BLACK – Leg, hind tibia hair color YELLOW OR BLACK – Abdomen, segment T2 hair color usually ALL YELLOW or occasionally all black – T4 hair color mostly or ALL BLACK – Found in and north or Canada (1)
 B. mixtus – Thorax, rear half of scutum hair color ranges from mostly YELLOW to mostly BLACK – Leg, hind tibia hair color YELLOW – Abdomen, segment T2 ALL YELLOW – T4 hair color ALL YELLOW – Primarily found from the Rocky Mountains WEST (1)
Male, B. caliginosus vs. B. vosnesenskii
 B. caliginosus – Thorax, scutellum hair color black with a FEW YELLOW hairs mixed in towards the rear, may need to look closely – Leg, middle or hind femur hair color YELLOW on the underside – Abdomen, T5 segment hair color black with a couple YELLOW hairs on each side of the segment and along the rear rim in a very thin border, yellow rim only one or two hairs thick – Difficult to tell apart from B. vosnesenskii and needs very close inspection of hair color (1)
 B. vosnesenskii – Thorax, scutellum hair color COMPLETELY BLACK – Leg, middle and hind femur hair color ALL BLACK – Abdomen, T5 segment hair color black with a small to large PATCH of YELLOW on each side, sometimes with only a small patch of black hairs in the center of the segment – Difficult to tell apart from B. caliginosus and needs very close inspection of hair color (1)
Male, B. centralis vs. B. fervidus vs. vandykei
 B. centralis –Thorax, hair color of rear half of scutum YELLOW, sometimes with a few dark hairs mixed in – Abdomen, segment T5 hair color usually BLACK, but sometimes bright orange – Found from the Rocky Mountains WEST (1)
 B. fervidus – Thorax, hair color of rear half of scutum a DISTINCT BAND OF BLACK – Abdomen, segment T5 hair color GOLD – Found throughout North America (1)
 B. vandykei – Thorax, hair color of rear half of scutum YELLOW, with no black hairs present – Abdomen, segment T5 hair color YELLOW or GOLD – Only found in California and perimeter areas of neighboring states (1)
Male, B. centralis vs. B. flavifrons
 B. centralis – Abdomen, T3 and T4 segment hair color ORANGE often bright orange – T5 hair color BLACK or often ORANGE (1)
 B. flavifrons – Abdomen, T3 and T4 segment hair color YELLOW, with T4 sometime half yellow and half black – T5 hair color always BLACK (1)
Male, B. centralis vs. B. sonorus
 B. centralis – Head, facial hair color YELLOW – Thorax, hair color beneath base of front wing YELLOW – Hind leg, long projecting hairs on rear edge of tibia YELLOW colored (1)
 B. sonorus – Head, facial hair color primarily LONG BLACK HAIRS mixed with some SHORT YELLOW hairs – Thorax, hair color beneath base of front wing BLACK – Hind leg, long projecting hairs on rear edge of tibia BLACK colored (1)
Male, B. citrinus vs. B. insularis
 B. citrinus – Abdomen, T4 segment hair color COMPLETELY BLACK – Found primarily east of the Rocky Mountains (1)
 B. insularis – Abdomen, T4 segment hair color HIGHLY VARIABLE ranging from all yellow to mostly black with only a little yellow on the edges, but with no specimens showing completely black hair – Ranges throughout the United States and Canada (1)
Male, B. citrinus vs. B. suckleyi
 B. citrinus – Thorax, scutellum hair color YELLOW WITH V- OR U-SHAPED PATCH OF DARK or no hair – Abdomen, T4 segment hair color ALL BLACK – T5 and T6 hair color ALL BLACK (1)
 B. suckleyi – Thorax, scutellum hair color YELLOW – Abdomen, T4 segment usually ALL YELLOW, but sometimes with small amounts of black in the center – T5 and T6 hair color HIGHLY VARIABLE ranging from all black to all yellow (1)
Male, B. crotchii vs. B. griseocollis vs. B. rufocinctus
 B. crotchii – Head, hair color on the side of the antennae all YELLOW with a very few black hairs mixed in – Thorax, color of hair below base of front wing YELLOW with BLACK PATCHES intermixed – Scutum, rear half hair color a distinct BAND OF BLACK – Abdomen, T2 segment hair color all YELLOW or yellow with black hairs along the center of the rear rim – Primarily found in western North America (1)
 B. griseocollis – Head, hair color on the sides of the antennae all YELLOW with a very few black hairs mixed in – Thorax, color of hair below base of front wing ALL YELLOW – Scutum, rear half hair color all YELLOW – Abdomen, T2 segment hair color BLACK with a YELLOW PATCH, sometimes orangish red, in the center of the segment, or yellow hairs along the front rim of the segment – Found throughout North America (1)
 B. rufocinctus – Head, hair color on the sides of the antennae BLACK – Thorax, color of hair below base of front wing ALL YELLOW – Scutum, rear half hair color all YELLOW – Abdomen, T2 segment hair color ALL YELLOW – Found throughout North America (1)
Male, B. distinguendus vs. B. perplexus
 B. distinguendus – Abdomen, T4 and T5 segment hair color ALL YELLOW – Species only found in Europe, with the exception of one recorded specimen from Alaska (1)
 B. perplexus – Abdomen, T4 segment hair color VARIES from all yellow, to yellow and black mixed, to all black – T5 hair color black and yellow mixed or all black – Species only found in North America (1)
Male, B. fervidus vs B. pensylvanicus - Tricky pair sometimes may not be separable so be cautious
 B. fervidus - The broad upper part of the mesepisternum almost always completely covered with yellow hairs, black hairs are usually present at the base of the segment near the legs and often coming up the anterior face along the head - On the tibia of the rear leg the hairs projecting outward from the anterior edge of the segment are clearly shorter than those on the posterior edge - Malar space always far wider than the width of the base of th mandibles - On average a smaller bee (1)
 B. pensylvanicus - The broad upper part of the mesepisternum almost always with some regularly spaced scattered long black hairs, on some individuals this can be extensive and the entire region can look dark, in others it is restricted to scattered hairs visible primarily after close inspection - On the tibia of the rear leg the hair projection outward from the anterior edge of the segment are about the same length or slightly longer than those on the posterior edge - Malar space often about equal to the width of the base of the mandible or only slightly longer - Many specimens will have extensive bright orange hair on T6-7 - On average a larger bee (1)
Male, B. fervidus vs. B. huntii vs. B. sonorus
 B. fervidus – Head, facial hair color mostly LONG BLACK HAIRS mixed with some SHORT YELLOW HAIRS – Thorax, hair color below base of front wing BLACK – Hind leg, long projecting hairs on rear edge of tibia BLACK colored – Abdomen, segment T2 through T4 hair color YELLOW or GOLD never bright orange – T5 hair color YELLOW or primarily yellow (1)
 B. huntii – Head, facial hair color YELLOW – Thorax, hair color below base of front wing YELLOW – Hind leg, long projecting hairs on rear edge of tibia YELLOW colored – Abdomen, segment T2 through T4 hair color YELLOW or BRIGHT ORANGE –T5 hair color YELLOW (1)
 B. sonorus – Head, facial hair color mostly LONG BLACK HAIRS mixed with some SHORT YELLOW HAIRS – Thorax, hair color below base of front wing BLACK – Hind leg, long projecting hairs on rear edge of tibia BLACK colored – Abdomen, segment T2 through T4 hair color YELLOW or GOLD never bright orange – T5 hair color BLACK (1)
Male, B. fervidus vs. B. perplexus
 B. fervidus – Head, hair color above ocelli primarily LONG BLACK HAIRS mixed some SHORT YELLOW hairs – Thorax, hair color of rear half of scutum a DISTINCT BAND OF BLACK – Abdomen, segment T5 hair color GOLD (1)
 B. perplexus – Head, hair color above ocelli YELLOW – Thorax, hair color of rear half of scutum YELLOW, with no black hairs present – Abdomen, segment T5 hair color DARK BROWN or BLACK, older specimens my appear a little bit yellowish (1)
Male, B. fervidus vs. B. sitkensis
 B. fervidus – Head, facial hair color LONGER BLACK hairs mixed with SHORTER LIGHT hairs – Thorax, scutum rear half hair color BAND OF BLACK – Leg, hind tibia hair color BLACK and short (1)
 B. sitkensis – Head, facial hair color ALL LIGHT – Thorax, scutum rear half hair color primarily YELLOW with some BLACK MIXED IN – Leg, hind tibia hair color YELLOW and long (1)
Male, B. flavifrons vs. B. sitkensis vs. B. vandykei
 B. flavifrons – 3 different forms – Form 1 – Thorax, scutum rear half hair color mostly or all BLACK – Abdomen, T1 and T2 hair color YELLOW – T3 through T6 hair color BLACK – Form 2 – Thorax, scutum rear half hair color mostly or all BLACK – Abdomen, T1 and T2 hair color YELLOW to ORANGE – T3 and T4 hair color ORANGE – T5 and T6 hair color BLACK – Form 3 – Thorax, scutum rear half hair color YELLOW – Abdomen, T1 and T2 hair color YELLOW – T3 and T4 hair color BLACK ON TOP half and YELLOW ON BOTTOM half – T5 and T6 BLACK (1)
 B. sitkensis – Thorax, scutum rear half hair color all BLACK or mostly black with some yellow hairs mixed in – Abdomen, T1 and T2 hair color YELLOW – T3 and T4 color BLACK ON TOP half and YELLOW ON BOTTOM half, in some cases, T4 may only have a few yellow hairs on the rear rim of the segment – T5 hair color BLACK – T6 hair color YELLOW (1)
 B. vandykei – Thorax, scutum rear half hair color YELLOW – Abdomen, T1 through T6 hair color YELLOW (1)
Male, B. flavifrons vs. B. sonorus
 B. flavifrons – Head, facial hair color ALL YELLOW – Thorax, hair color below base of front wing ALL YELLOW – Leg, tibia hair color YELLOW (1)
 B. sonorus – Head, facial hair color ALL BLACK – Thorax, hair color below base of front wing ALL BLACK – Leg, tibia hair color BLACK (1)
Male, B. frigidus vs B. mixtus
 B. frigidus - Hair on the front of the scutum entirely yellow with no intermixture of black hairs - Antennal segments all with uniform very short hair (1)
 B. mixtus - Hair on the very front of the scutum a mix of yellow and black hairs - Hairs on basal flagellar antennal segments with tufts of long hair on inner surfaces (1)
Male, B. frigidus vs. B. occidentalis
 B. frigidus – Thorax, hair color below base of front wing YELLOW TOWARDS FRONT AND BLACK TOWARDS REAR – Abdomen, segment T1 hair color YELLOW – T3 hair color BLACK (1)
 B. occidentalis – Thorax, hair color below base of front wing ALL YELLOW - Abdomen, segment T1 hair color BLACK – T3 hair color YELLOW (1)
Male, B. huntii vs. B. melanopygus
 B. huntii – Thorax, scutum hair color front half ALL YELLOW or gold – Leg, hind tibia hair color YELLOW – Abdomen, T5 segment hair color YELLOW often with a patch of black in the center, sometimes yellow and black mix (1)
 B. melanopygus – Thorax, scutum hair color front half YELLOW AND BLACK MIX or primarily yellow with a few black hairs mixed in – Leg, hind tibia hair color BLACK, although it can appear yellow in some faded museum specimens – Abdomen, T5 segment hair color BLACK or mostly black (1)
Male, B. insularis vs. B. suckleyi
 B. insularis – Head, hair color above antennae usually tufts of YELLOW BORDERED BY BLACK – Specimens where hair color above antennae is all black are indistinguishable from B. suckleyi – Ranges throughout the United States and Canada (1)
 B. suckleyi – Head, hair color above antennae ALL BLACK – Indistinguishable from B. insularis specimens that have all black hair above antennae – Found primarily from the Rocky Mountains WEST (1)
Male, B. jonellus vs. B. occidentalis
 B. jonellus – Thorax, hair color below base of front wing ALL YELLOW – Abdomen, segment T1 hair color YELLOW (1)
 B. occidentalis – Thorax, hair color below base of front wing ALL YELLOW - Abdomen, segment T1 hair color BLACK (1)
Male, B. jonellus vs. B. perplexus vs. B. vagans
 B. jonellus – Thorax, rear half or scutum hair color mostly or ALL BLACK – Abdomen, segment T3 hair color BLACK – T5 hair color YELLOW or occasionally a yellow and black mix – T6 hair color YELLOW (1)
 B. perplexus – Thorax, rear half of scutum hair color ALL YELLOW – Abdomen, segment T3 hair color all YELLOW – T5 and T6 hair color all or almost ALL BLACK (1)
 B. vagans – Thorax, rear half of scutum hair color ALL YELLOW or all yellow with a few black hairs mixed in – Abdomen, segment T3 hair color BLACK – T5 and T6 hair color BLACK with a few yellow hairs on the outer sides (1)
Male, B. jonellus vs. B. sitkensis
 B. jonellus – Head, hair color above antennae a fairly even mix of YELLOW AND BLACK – Abdomen, segment T3 hair color ALL BLACK – T4 hair color usually ALL BLACK or sometimes mixed with yellow or white (1)
 B. sitkensis – Head, hair color above antennae primarily YELLOW with some TALL BLACK HAIRS MIXED IN – Abdomen, segment T3 and T4 hair color BLACK on the FRONT HALF and YELLOW on the REAR HALF – May be hard to see black vs. yellow in older museum specimens (1)
Male, B. melanopygus vs. B. sonorus vs. B. vandykei
 B. melanopygus – Head, hair color above ocelli primarily YELLOW sometimes with some black hairs mixed in – Thorax, scutum hair color front half YELLOW AND BLACK MIX or primarily yellow with a few black hairs mixed in, rear half primarily BLACK mixed with some yellow hairs – Below base of front wing, hair color ALL YELLOW – Leg, hind tibia hair color BLACK, and long, hairs can appear yellow in some older faded museum specimens – Abdomen, T2 and T3 segment hair color BRIGHT ORANGE to reddish (1)
 B. sonorus – Head, hair color above ocelli primarily BLACK sometimes with some yellow hairs mixed in – Thorax, scutum hair color front half YELLOW or golden, rear half ALL BLACK – Below base of front wing, hair color ALL BLACK or at least partially black, older museum specimens may be faded and hard to tell – Leg, hind tibia hair color BLACK and short – Abdomen, T2 and T3 segment hair color YELLOW (1)
 B. vandykei – Head, hair color above ocelli ALL YELLOW – Thorax, scutum hair color front half ALL YELLOW, back half ALL YELLOW occasionally with a couple black hairs mixed in – Below base of front wing, hair color ALL YELLOW – Leg, hind tibia hair color YELLOW – Abdomen, T2 and T3 hair color YELLOW (1)
Male, B. melanopygus vs. B. sylvicola
 B. melanopygus – Head, hair color above antennae YELLOW sometimes with a few black hairs mixed in – Thorax, scutum hair color front half YELLOW AND BLACK MIX or primarily yellow with a few black hairs mixed in – Leg, hind tibia hair color BLACK, although it can appear yellow in some faded museum specimens (1)
 B. sylvicola – Head, hair color above antennae mostly BLACK usually with some yellow hairs mixed in, very rarely primarily yellow – Thorax, scutum hair color front half ALL YELLOW or gold – Leg, hind tibia hair color YELLOW (1)
Male, B. melanopygus vs. B. ternarius
 B. melanopygus – Thorax, scutum hair color front half YELLOW AND BLACK MIX or primarily yellow with a few black hairs mixed in – Leg, hind tibia hair color BLACK, although it can appear yellow in some faded museum specimens (1)
 B. ternarius – Thorax, scutum hair color front half ALL YELLOW or gold – Leg, hind tibia hair color YELLOW (1)
Male, B. mixtus vs. B. neoboreus
 B. mixtus – Head, hair color above antennae YELLOW – Leg, hind tibia hair color YELLOW – Abdomen, T4 and T5 segment hair color ORANGE (1)
 B. neoboreus – Head, hair color above antennae BLACK – Leg, hind tibia hair color BLACK – Abdomen, T4 and T5 segment hair color BLACK (1)
Male, B. mixtus vs. B. occidentalis vs. B. perplexus
 B. mixtus – Thorax, rear half of scutum hair color primarily YELLOW with few black hairs mixed in – Leg, hind tibia hair color YELLOW – Abdomen, segment T1 hair color YELLOW (1)
 B. occidentalis – Thorax, rear half of scutum hair color all or almost ALL BLACK – Leg, hind tibia hair color YELLOW – Abdomen, segment T1 hair color BLACK (1)
 B. perplexus – Thorax, rear half of scutum hair color all or almost ALL YELLOW – Leg, hind tibia hair color BLACK – Abdomen, segment T1 hair color YELLOW (1)
Male, B. mixtus vs. B. sitkensis vs. B. vagans
 B. mixtus – Leg, hind tibia hair color YELLOW – Abdomen, segment T3 hair color HIGHLY VARIABLE, encompassing the states of both B. sitkensis and B. vagans – T5 and T6 hair color primarily YELLOW or ORANGISH (1)
 B. sitkensis – Leg, hind tibia hair color YELLOW – Abdomen, segment T3 hair color BLACK on the front half and YELLOW along the rear rim – T5 hair color primarily BLACK – T6 hair color YELLOW to VERY SLIGHTLY ORANGISH (1)
 B. vagans – Leg, hind tibia hair color BLACK – Abdomen, segment T3 hair color BLACK – T5 and T6 hair color BLACK (1)
Male, B. mixtus vs. B. vandykei
 B. mixtus – Abdomen, T3 segment hair color BLACK or sometime a mix of black and yellow – T4 and T5 hair color ORANGE, sometimes appears yellow in older faded museum specimens – Found throughout western North America (1)
 B. vandykei – Abdomen, T3 and T4 segment hair color YELLOW – T5 hair color YELLOW or sometimes black – Only found in California and its neighboring states (1)
Male, B. moderatus vs. B. occidentalis
 B. moderatus – Head, facial hair color BLACK, YELLOW, or a MIX of the two – Thorax, scutellum hair color almost always BLACK, but some specimens do have yellow instead – Abdomen, T1 segment hair color almost always BLACK, occasionally yellow – Most of the time there is no consistent way to tell B. moderatus apart from B. occidentalis using morphological features, they both look identical (1)
 B. occidentalis – Head, facial primarily YELLOW sometimes with a few black hairs mixed in – Thorax, scutellum hair color YELLOW – Abdomen, T1 segment hair color BLACK – Most of the time there is no consistent way to tell B. moderatus apart from B. occidentalis using morphological features, they both look identical (1)
Male, B. occidentalis vs. B. sonorus vs. B. vandykei
 B. occidentalis – Head, hair color above ocelli primarily YELLOW – Thorax, scutum hair color rear half all BLACK – Below base of front wing, hair color ALL BLACK or at least partially black, older museum specimens may be faded and hard to tell – Leg, hind tibia hair color YELLOW with some darker hairs mixed in and LONG (1)
 B. sonorus – Head, hair color above ocelli primarily BLACK sometimes with some yellow hairs mixed in – Thorax, scutum hair color rear half ALL BLACK – Below base of front wing, hair color ALL BLACK or at least partially black, older museum specimens may be faded and hard to tell – Leg, hind tibia hair color BLACK and SHORT (1)
 B. vandykei – Head, hair color above ocelli ALL YELLOW – Thorax, scutum hair color rear half ALL YELLOW occasionally with a couple black hairs mixed in – Below base of front wing, hair color ALL YELLOW – Leg, hind tibia hair color YELLOW and LONG (1)
Male, B. occidentalis vs. B. sylvicola
 B. occidentalis – Thorax, below base of front wing, hair color all or mostly BLACK, occasionally just a little bit of black closer to the rear – Abdomen, T1 segment hair color BLACK or almost all black – T2 hair color BLACK, YELLOW, or MIX of black and yellow usually one color in the middle and one on the sides – T2 hair color BLACK, YELLOW, or MIX of black and yellow usually one color in the middle and one on the sides (1)
 B. sylvicola – Thorax, below base of front wing, hair color ALL YELLOW – Abdomen, T1 segment hair color YELLOW – T2 and T3 hair color BRIGHT ORANGE or sometimes lighter in older specimens (1)
Male, B. pensylvanicus vs. B. sonorus
 B. pensylvanicus – Found throughout North America – Indistinguishable from B. sonorus (1)
 B. sonorus – Found in southwestern North America – Indistinguishable from B. pensylvanicus (1)
Male, B. perplexus vs. B. sitkensis
 B. perplexus – Leg, hind tibia hair color BLACK – Abdomen, segment T3 hair color YELLOW (1)
 B. sitkensis – Leg, hind tibia hair color YELLOW – Abdomen, segment T3 hair color BLACK on the front half and YELLOW along the rear rim (1)
Male, B. suckleyi vs. B. variabilis
 B. suckleyi – Thorax, hair color below wing base ALL YELLOW with no black hair at all present – Scutellum hair color YELLOW – Abdomen, T1 segment hair color ALL YELLOW or black in the center with yellow on the edges – B. suckleyi is primarily found from the Rocky Mountains WEST but its range slightly overlaps B. variabilis’s more eastern range (1)
 B. variabilis – Thorax, hair color BLACK or BLACK WITH A PATCH OF YELLOW RIGHT AT THE BASE – Scutellum hair color YELLOW WITH V- OR U-SHAPED PATCH OF BLACK or no hair – Abdomen, hair color ALL BLACK or almost all black with a few yellow hairs mixed – B. variabilis is primarily found east of the Rocky Mountains but its range slightly overlaps that of B. suckleyi’s more western range (1)
Male, B. sylvicola vs. B. sonorus vs. B. vandykei
 B. sonorus – Head, hair color above ocelli primarily BLACK sometimes with some yellow hairs mixed in – Thorax, scutum hair color front half YELLOW or golden, rear half ALL BLACK – Below base of front wing, hair color ALL BLACK or at least partially black, older museum specimens may be faded and hard to tell – Leg, hind tibia hair color BLACK and short – Abdomen, T2 and T3 segment hair color YELLOW (1)
 B. sylvicola – Head, hair color above ocelli ALL YELLOW – Thorax, scutum hair color front half ALL YELLOW, rear half ALL BLACK – Below base of front wing, hair color ALL YELLOW – Leg, hind tibia hair color YELLOW – Abdomen, T2 and T3 hair color BRIGHT ORANGE, older faded museum specimens may appear to be yellow (1)
 B. vandykei – Head, hair color above ocelli ALL YELLOW – Thorax, scutum hair color front half ALL YELLOW, back half ALL YELLOW occasionally with a couple black hairs mixed in – Below base of front wing, hair color ALL YELLOW – Leg, hind tibia hair color YELLOW – Abdomen, T2 and T3 hair color YELLOW (1)
Male, parasitic vs non-parasitic
 Non-parasitic, common, in most but not all species the outer surface of the hind tibia has longer hairs along the front and rear edges with a region of bare or much shorter and less dense hairs in the center, in cross-section, this face also often flattened or deformed slightly from bi-lateral symmetry, the thickest portion usually shifted towards the front edge, fervidus and pensylvanicus are the main exceptions, having short uniform black hairs throughout, but tibia is thicker towards the front edge and underside of segment exceptionally flat, ocelli can be below the level of the eyes or if at the level of the eyes the lateral ocelli are equally distant between the eye and rear head margin or closer to the rear margin, warning, a few species do have ocelli clearly closer to the eye (42)
 Parasitic, relatively rare to uncommon, outer surface of hind tibia uniformly hairy in density and hair length, hairs may be long or short, shape in cross-section is symmetrical, gently rounded with thickest portion running along center or only very slightly towards the front edge of the leg, ocelli always at level with the tops of the eyes, lateral ocelli always much nearer to eye than to rear margin of head (6)
PSITHYRUS ONLY - Female, B. citrinus vs B. variabilis
 B. citrinus - On the scutum there is sometimes a black spot centrally, although it never extends laterally as far as the tegulae - The hair of the mesepisternum is usually entirely light or nearly so but often it becomes dark ventrally (1)
 B. variabilis - There is always a black spot medially on the scutum and it often extends far enough laterally to reach the tegulae - The hair of the mesepisternum is largely black, although there is often some limited degree of yellow hair here (1)
PSITHYRUS ONLY - Females, Abdomen, T6, hair color - CAREFUL, hair may have been rubbed off
 Longer, black hairs present at least mediobasally, not counting any hairs that may be present in the dense lateral patches if present (4)
 No longer black hairs present on T6 (4)
PSITHYRUS ONLY - Females, Abdomen, T6, lateral hair patches - CAREFUL, hair may have been rubbed off
 Hair relatively uniformly present throughout T6, if of varying density then without seemingly elevated lateral hair patches running along the edges of T6 (4)
 Lateral hair patches present, hair density SIGNIFICANTLY higher along the lateral sides of the segment such that the surface integument is completely or nearly completely obscured along the sides, the patches appearing to rise off the surface in the form of hairy ridges (3)
Queen vs Worker - General guidance - It is often difficult to tell queens from workers without a direct comparison between the two
 Queen, usually much larger, active and most abundant earlier in spring (41)
 Worker, smaller and often more variable in size, active from mid-spring into summer (40)
Queen, B. affinis, B. bimaculatus, B. perplexus, B. vagans - Tricky, look closely at the following characters
 B. affinis - Space between eye and mandible clearly less than width of the base of mandible - Hairs behind ocelli black or at most with only a few yellow - Hairs on thorax below front wing all yellow - Hairs on T2 all yellow - Hairs on T6 all black - This species has not been regularly seen since 2002, may be extinct, please report all sightings (1)
 B. bimaculatus - Space between bottom of eyes and mid-point of mandible equal to or longer than width of base of mandible - Hair on thorax below front wing yellow - Hair on T2 with at least some yellow at mid-point of base of segment, can extend to most of segment but always with black patches at the far sides (1)
 B. perplexus - Careful the queen looks quite different from the workers and males - Space between the eye and mandible about equal or greater than width of base of mandible - Hairs behind ocelli all or almost all yellow - Hairs on thorax below front wing roughly yellow on top two-thirds to a half and black below - Hairs on T2 all yellow or with a smidge of black hairs on the far sides - Hairs on T6 with at least a few LONG yellow hairs near the edges near the tip where it abuts S6, note that there is almost always a fringe of extremely short dense yellow hairs immediately fringing the rim (1)
 B. vagans - Area between eye and mandibles as long or longer than width of base of mandibles - Hairs behind ocelli largely or entirely yellow - Hairs on thorax below front wings all yellow - Hairs on T2 often with band of black hairs right at the rim - Hairs on T6 all black, but as in B. perplexus, often has a fringe of extremely short dense yellow hairs along the rim where it borders with S6 (1)
SUBGENUS PSITHYRUS ONLY - Females, B. fernaldae vs other parasitic species
 Other Psithyrus species - On S6, the projection is either unnoticeable or with its length only equal to its minimum width, often appearing as a small knob when not obscured by hair - When viewed in profile, the upper surface of T6 forms a smooth concave or convex curve or straight line (5)
 B. fernaldae - On the apex of S6, there is a long, ventrally-directed, bare of hairs, acutely shaped, curved projection or plate, that looks similar to the spike-like nail of a dog, having a length at least twice its minimum width when viewed head-on from the rear, often appearing as a heavily curved claw - When viewed in profile, the upper surface of T6 displays a clear oblique bend in the profile, that bend occurring about one third of the way from the tip (1)
SUBGENUS PSITHYRUS ONLY - Male, head, antennal length of first three flagellomeres
 Third flagellar segment normal, about equal in length to the first flagellomere (3)
 Third flagellar segment very long, equal in length to the first and second flagellomeres combined or nearly so (3)
Sex, antennal segment number
 Female, 12 (90)
 Male, 13 (48)
State or province where bee was collected
 British Columbia (87)
 Alberta (84)
 Arctic tundra or taiga (77)
 CA (75)
 Quebec (73)
 WA (72)
 Ontario (71)
 MT (70)
 CO (69)
 OR (69)
 WY (69)
 UT (66)
 ID (63)
 SD (60)
 MN (59)
 MI (58)
 WI (58)
 AK (56)
 ME (55)
 NM (55)
 NY (55)
 Saskatchewan (54)
 NE (53)
 CT (52)
 MA (52)
 NH (52)
 VT (52)
 Manitoba (51)
 IL (50)
 IN (50)
 NV (50)
 WV (50)
 MD (49)
 NJ (49)
 PA (49)
 VA (49)
 ND (48)
 AZ (47)
 GA (47)
 NC (47)
 SC (47)
 TN (47)
 Yukon (47)
 OH (44)
 RI (43)
 KY (41)
 Prince Edward Island (41)
 DC (39)
 DE (39)
 New Brunswick (38)
 Nova Scotia (38)
 IA (34)
 Newfoundland and Labrador (34)
 Northwest Territories (34)
 KS (32)
 AL (28)
 MS (28)
 AR (23)
 TX (23)
 MO (20)
 FL (19)
 LA (15)
 OK (14)
 Nunavut (11)
Subgenus
 Pyrobombus (58)
 Bombus (15)
 Cullumanobombus (15)
 Psithyrus (12)
 Thoracobombus (12)
 Alpinobombus (11)
 Subterraneobombus (9)
 Bombias (6)
Thorax, below base of front wing, hair color
 Light (109)
 Light and dark hairs mixed or in patches (65)
 Black, though usually with a small amount of yellow hair at the very top, covering not more than about 1/4 of segment (61)
Thorax, scutellum, color of hairs
 Light (113)
 Light and dark hairs mixed or in patches (83)
 Black (54)
Thorax, scutum, color of hairs in front third
 Light (130)
 Both light and dark hairs mixed (46)
Thorax, scutum, color of hairs on rear half of plate
 Black (112)
 Light and dark hairs mixed or in patches (91)
 Light (44)
Worker - B. affinis, B. bimaculatus, B. perplexus, B. vagans
 B. affinis - Space between eye and mandible clearly short or approaching equal to the width of the base of the mandible - Hairs behind ocelli all black or with only a few yellow hairs - Hairs on T2 and at times T1 with brownish tinted hairs in the center of the segments that contrast with the yellow - Hairs on T3-6 all black - This species has not been regularly seen since 2002, may be extinct, please report all sightings (1)
 B. bimaculatus - Hairs behind ocelli black towards the front and yellow towards the rear - Space between bottom of eyes and mid-point of mandible equal to or longer than width of base of mandible - Hairs on T2 with at least some yellow at mid-point of base of segment, can extend to most of segment but always with black patches at the far sides - Hairs on T3-6 black (1)
 B. perplexus - Space between eye and mandible equal to or longer than width of base of mandible - Mesepisternum usually with yellow hairs on the upper half to one-third and black on the lower half to two-thirds - Abdomen hair color more variable than the other species, entire abdomen often looks yellow from a distance but on closer inspection, T4 - 5 is usually a washed out black or dark color, T3 may also be dark but can vary from mixed to entirely yellow, T6 with some LONG yellow hairs along its rim, the other species have all dark long hairs, note that in this and other species the rim is fringed by short dense yellow hair, clearly different than the loose long scattered long hairs on the rest of the segment - The hairs on the abdomen relatively less dense and slightly longer than the other species - Note that the queen looks quite different (1)
 B. vagans - Hairs behind ocelli black towards the front and yellow towards the rear - Area between eye and mandible as long or longer than width of base of mandible - Hairs on mesepisternum all yellow - Hairs on T1-2 yellow - Hairs on T3-6 black - Hairs on T6 black with at most a few VERY short yellow hairs along the rim (1)
Worker, B. bifarius vs B. californicus
 B. bifarius - Malar space, distance between the mid-point of the mandible s attachment and the bottom of the eye, shorter than or nearly equal to the width of the base of the mandible - Scutellum, hair color, ALWAYS with more yellow hair than black hair, any black hair being restricted to the center of the scutellum in a distinctive longitudinal stripe either formed by the black hair or a bare medial area, lateral patches strongly yellow with no black hairs - Head, hair color above antennal sockets and ocelli, primarily yellow, black hairs often present but restricted to the the lateral and posterior edges of the post-antennal patch and the anterior edge of the post-ocelli patch - Scutum, hair color in the anterior third, most often with a noticeable amount of black hair intermixed with the dominant yellow hairs - In direct comparison, smaller - Looking from above, the yellow on the scutellum separated by a V of black hairs in the center often stands out (1)
 B. californicus - Malar space, distance between the mid-point of the mandible s attachment and the bottom of the eye, longer than the width of the base of the mandible - Scutellum, hair color, often but not always with more black hair than yellow hair, with black hair found intermixed throughout the scutellum, although some specimens from Wyoming have been seen to have more yellow than black hairs - Head, hair color above antennal sockets and ocelli, primarily black, few yellow hairs present if any - Scutum, hair color in the anterior third, without any black hairs, or if black hairs present then not evenly intermixed and instead restricted to the rear portion of the anterior third of the scutum - In direct comparison, larger - Looking from above, this is a comparatively darker bee, the rear half of the scutum, all of the scutellum and the first tergites appear dark despite the presence, at times, of some intermixed yellow hairs (1)