Some interpretive notes:
If this is your first rodeo, then start at the beginning. The concepts of males and cuckoos are good to have a feel for when going out to observe.
Using the key from the beginning is also a good way to encounter and learn the various technical terms for bumble body parts (e.g., scutum, stergite). The colored blocks on the right hand side can be clicked on to get more information about the particular bumble bee part in question.
Another early objective is gaining confidence in which bumble bees show a corbiculum (pollen basket).
Once you have used the key a couple of times and are confident your bee in question has a corbiculum, it may be faster to jump down to the portion of the key most likely appropriate. Those groups are:
Step
Description
Go to #
Comments or link to diagram or species page
Separating Females from Cuckoos and Males
Cuckoo Queens vs. all males
2′
Any individual bumble bee with a hairy rear leg, lacking a pollen basket that is not a cuckoo queen
ID
This key is restricted to queens and female bumble bees at this time. You can start the key at Step 5–if the male (drone) is similar to the queens or workers the key may be of assistance.
3′
T4 without black notch
4
4 (3′)
T4 yellow, T5 all black, occiput with yellow hairs
ID
4′
T5 with some yellow, black notch on T5, occiput with mainly black hairs
ID
Suckley cuckoo bumble bee, Bombus suckleyi (very rare)
5′
No white areas as described above
7
Bumbles showing White
Bumbles showing Yellow
7′
May have some yellow, but other colors also. May be striped.
9
7 (5′)
Bumble bee predominately yellow
8#
8#’
T4 mainly yellow
8
Bumbles showing RED
Separating Reds into 2 groups
11 (10)
Scutum yellow, T1 & T2 yellow, T3 & T4 red/orange, T5 black
ID
11′
Not as above
12
12 (11′)
Scutum cloudy, T1 & T2 yellow, T3 & T4 orange and/or black, T5 black
ID
Yellow head bumble bee, Bombus flavifrons, RED morph
12′
Not as above
13
13 (12′)
T2 & T3 red / orange
14
13′
T2 OR T3 show orange
17
14 (13)
Scutum cloudy
15
15 (14)
Black inverted triangle on scutellum, range associated with San Juan Islands, often black notch on T2
ID
15′
T1 yellow, T4 black with white hairs in horizontal line
ID
17 (13′)
Scutum and Scutellum both yellow, T2 usually shows at least some yellow, small body, very short face
ID
Red at hind end of abdomen
18 (10)
Scutum cloudy (yellow, with black hairs mixed in)
19
18′
Scutum yellow
20
19 (18)
T3 orange, sometimes with black; T4 & T5 orange; distinct red tail
ID
No RED on Abdomen
22
T1 & T4 white or yellow; inverted black triangle on scutellum
ID
22′
Not as above
23
23′
Face yellow
24
Bumbles with black end of abdomen
26 (21′)
Thorax & T1 thru T4 yellow, T5 black, corbiculum present
ID
26′
Not as above
27
27′
Not as above
28
28
T3 golden or yellow
29
28′
Not as above
30
29′
No black dot between wings
ID
Morrison bumble bee, Bombus morrisoni (rare in WA, more common in OR and ID)
30 (28′)
Scutum cloudy, T1 & T2 yellow, possibly with black notches
ID
30′
Not as above
31
31 (30′)
T1 yellow, T2 with yellow or brown, relatively large bodied
ID
This is our start. Version 1.1
If you find color morphs that fall outside this key, please bring them to our attention so we can expand the key appropriately.
Teamwork for the Win!
1