Western bumblebee
| Bombus occidentalis | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Apidae |
| Genus: | Bombus |
| Subgenus: | Bombus |
| Species: | B. occidentalis |
| Binomial name | |
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Bombus occidentalis (Greene, 1858) |
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| The range of Bombus occidentalis. (Dashed line indicates former range within the United States (not Canada).) | |
Bombus occidentalis, the western bumblebee, is one of around 30 bumblebee species present in the western United States and western Canada. A recent review of all of its close relatives worldwide appears to have confirmed its status as a separate species.
Western bumblebee workers have three main color variations. The first color variation is found from northern California, north to British Columbia, and east to southwest Saskatchewan and Montana.B. occidentalis in these areas have yellow hair on front part of thorax. They are also marked by black hair segments on the basal section of the fourth abdominal segments have black hair and whitish lower edge of the fourth and fifth abdominal segments. In addition, they also have sparse whitish hairs that may appear black on the sixth abdominal segment, and an entirely black head.
The second color variation is found along the central coast in California. It has yellow hair on the sides of the second abdominal segment and all of the third abdominal segment and a reddish-brown hair on fifth abdominal segment.
The third color variation is found from the Rocky Mountains to Alaska. It has yellow hair on the thorax behind the wings and on the rear of the second and all of the third abdominal segments.
All insects have three main body parts; the head, thorax, and abdomen. Bumblebee species identification tends to refer to colorations on the abdominal segments. The abdominal segments are numbered from T1 to T6 (T7 if male) starting from the abdominal segment closest to the thorax and then working ventrally.
A few ways are used to determine the sex of the western bumblebee. The males (drones) have seven abdominal segments, while the females (queens and workers) have only six. The drones' antennae have 13 segments, while the females have only 12. Drones have no stingers. Additionally, the hind legs of the females tend to be wider and fatter with a pollen basket often visible. Drones have thinner hind legs that do not have pollen baskets. Another clue to sexual identity among B. occidentalis species is when they are being observed. Queens are the first to appear in the spring and then the workers appear after. All females can then be seen throughout the summer and into early fall. The drones only appear in the late summer and early fall.
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Wikipedia