ANSWER THIS FIRST! The Western portion of the guide is usable with caution, let us know if you have problems resolving any species | Abdomen, T1, hair color, not counting the hairs present on the anterior portion of the segment that faces the propodeum | Abdomen, T2, hair color | Abdomen, T3, hair color | Abdomen, T4, hair color | Abdomen, T5, hair color | Females, parasitic vs non-parasitic queens and workers | Head, color of hairs just behind ocelli | 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 | Head, malar space, the space between mid-point of attachment of mandible and very bottom of eye compared to width of base of mandible | Head, ocelli, position relative to imaginary line across tops of eyes | Male, parasitic vs non-parasitic | Queen vs Worker - General guidance - It is often difficult to tell queens from workers without a direct comparison between the two | Sex, antennal segment number | State or province where bee was collected | Subgenus | Thorax, below base of front wing, hair color | Thorax, scutellum, color of hairs | Thorax, scutum, color of hairs on rear half of plate

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1. ANSWER THIS FIRST! The Western portion of the guide is usable with caution, let us know if you have problems resolving any species

811. EASTERN - Click here for completed and well tested guide to eastern species    1422. Click here for guide for all species including western species   
2. State or province where bee was collected    [Explain]

60AK    28AL    23AR    47AZ    84Alberta    81Arctic tundra or taiga    87British Columbia    75CA    69CO    52CT    39DC    39DE    19FL    47GA    57IA    63ID    50IL    50IN    32KS    41KY    15LA    52MA    49MD    55ME    58MI    69MN    29MO    28MS    70MT    51Manitoba    47NC    56ND    53NE    52NH    49NJ    55NM    50NV    55NY    38New Brunswick    34Newfoundland and Labrador    38Northwest Territories    38Nova Scotia    15Nunavut    44OH    14OK    69OR    71Ontario    55PA    41Prince Edward Island    73Quebec    43RI    47SC    65SD    54Saskatchewan    47TN    23TX    66UT    49VA    52VT    72WA    66WI    50WV    69WY    51Yukon   
3. Sex, antennal segment number

93Female, 12    49Male, 13   


4. Queen vs Worker - General guidance - It is often difficult to tell queens from workers without a direct comparison between the two

43Queen, usually much larger, active and most abundant earlier in spring    41Worker, smaller and often more variable in size, active from mid-spring into summer   
5. Females, parasitic vs non-parasitic queens and workers

87Non-Parasitic, common species, outer part of tibia largely hairless, flat, or concave, and rimmed by long hairs    6Parasitic, rare to uncommon species, hairs on outer face of tibia uniform in density and length throughout, tibia uniformly convex   


6. Male, parasitic vs non-parasitic

43Non-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    6Parasitic, 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   


7. Thorax, scutum, color of hairs on rear half of plate

116Black    44Light    91Light and dark hairs mixed or in patches   



8. Thorax, scutellum, color of hairs

54Black    113Light    87Light and dark hairs mixed or in patches   



9. Thorax, below base of front wing, hair color

65Black, though usually with a small amount of yellow hair at the very top, covering not more than about 1/4 of segment    109Light    67Light and dark hairs mixed or in patches   



10. Abdomen, T1, hair color, not counting the hairs present on the anterior portion of the segment that faces the propodeum

39All black    109All yellow or off-white    51Light and dark hairs mixed or in patches    21With strong rust, brown, orange, red HIGHLIGHTS or all orange   




11. Abdomen, T2, hair color

41All black    100All yellow or off-white    59Light and dark hairs mixed or in patches    48With strong rust, brown, orange, red HIGHLIGHTS or all orange   




12. Abdomen, T3, hair color

87All black    61All yellow or off-white    59Light and dark hairs mixed or in patches    49With strong rust, brown, orange, red HIGHLIGHTS or all orange   




13. Abdomen, T4, hair color

8All PURE WHITE, NOT light yellow    87All black    74All yellow or off-white    77Light and dark hairs mixed or in patches    49With strong rust, brown, orange, red HIGHLIGHTS or all orange   





14. Abdomen, T5, hair color

10All PURE WHITE, NOT light yellow    108All black    50All yellow or off-white    67Light and dark hairs mixed or in patches    29With strong rust, brown, orange, red HIGHLIGHTS or all orange   





15. Head, malar space, the space between mid-point of attachment of mandible and very bottom of eye compared to width of base of mandible

94Clearly longer    70Clearly shorter    86Roughly equal   



16. 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

94Black    106Both light and dark hairs    70Light   



17. Head, color of hairs just behind ocelli

70Black    109Both light and dark hairs    101Light   



18. Head, ocelli, position relative to imaginary line across tops of eyes

129About right on the line    25Distinctly below   


19. Subgenus

11Alpinobombus    6Bombias    15Bombus    15Cullumanobombus    12Psithyrus    62Pyrobombus    9Subterraneobombus    12Thoracobombus