|Bombus vandykei on a native Phacelia|
|Prime bumble bee habitat: Wyethia angustifolia blooming in part of the Vesper Meadow Restoration Preserve|
Vesper Meadow Restoration Preserve
Vesper Meadow is a privately owned 403 acre upland wet meadow in the heart of the Cascade-Siskiyou National Monument. The Vesper Meadow Education Program, which operates at the meadow and surrounding forest acreage, brings together scientists, students of all ages, and the public to study the local ecosystem and cultural significance of the land. One of the goals of the Preserve is to monitor wildlife of all sorts, from birds to plants to insects. Pollinators, especially butterflies and bees, are also being documented and monitored by organizing focused bioblitzes. Typically taking place over the course of a single day, a bioblitz is when a group of volunteer citizen scientists attempt to record as many living species as possible in a given area.
|Bombus vosnesenskii on Solidago at Vesper Meadow|
|Bombus flavifrons on Agastache urticifolia|
Bumble Bees 101
I will now provide a basic introduction to some of the bumble bees we've identified from Vesper Meadow. But first, a little about bumble bees. Bumble bees (genus Bombus) are cousins of the honeybees (genus Apis). Bumble bees are found around the world in temperate regions, most north of the equator (with the exception of South America where a handful of species are found), with the highest species richness from the Tibetan Plateau westward to the Alps. Most species are eusocial, like honeybees, except a smaller proportion of species which are social parasites (subgenus Psithyrus, they expropriate established nests of non-parasitic species for their own reproductive gains). In contrast, honeybees aren't native to the Americas and the genus Apis contains no social parasites.
|Bombus californicus on Wyethia angustifolia|
|Bombus bifarius s.l. (B. vancouverensis nearcticus)|
There also may be one or two of the socially parasitic bumble bees, subgenus Psithyrus, though no sightings or specimens have been confirmed as of this writing. The Oregon Bee Atlas expects to find the Fernald cuckoo bumble bee (B. fernaldae, syn. flavidus) and the Indiscriminate cuckoo bumble bee (B. insularis) in Oregon, but very few specimens have been vouchered. Social parasitic bumble bees have only two castes, female ("queens") and male, unlike other bumble bees which have queens, workers, and males. Rather than building their own nests, Psithyrus females (not technically queens since there is no worker caste) invade established nests and take them over, using the host workers to rear her young. This results in killing the colony since workers are no longer produced, only reproductive males and females of the social parasites. This seems harsh, but their presence would indicate a healthy host population. Psithyrus females can be identified by having no corbiculae.
The following are a selection of bees I've photographed or collected for the Oregon Bee Atlas and Vesper Meadow Bumble Blitz. For the Bumble Blitz, we will be using the capture, chill, release method. This involves netting bees, putting them in vials, and chilling them in a cooler so we can take detailed photos of them for identification. This is in contrast to netting bees, placing them in a kill jar (it's more humane than it sounds), and pinning them for identification under a microscope. Both collection methods have pros and cons. There are some bees that are very difficult to identify in the field, which is where pinned specimens may be superior. However, catch-and-release doesn't come with any moral ambiguity. As you will notice, photos don't always capture every characteristic necessary to assuredly identify some species. The best advice is to take as many good photos as possible, and hope you've captured the right angles.
White-Shouldered Bumble Bee - Bombus appositus
The white-shouldered bumble bee, Bombus appositus, has a general appearance of being well groomed with short, even hair all over. As the common name suggests, this bee has white patches on the anterior of the thorax, with a black band between the wing bases. The face and posterior of the thorax is either white or yellow, with the abdomen completely yellow or tawny buff. The white-shouldered bumble bee nests both underground and on the surface, such as within dense grass tussocks.
California Bumble Bee - Bombus californicus
Bombus californicus (syn. B. fervidus californicus) is very similar to both vosnesenskii and vandykei, all are black with yellow bands on the thorax and a yellow band of hair towards the tip of the abdomen on the third or fourth segments (also called tergites). B. californicus differs from the lookalikes by having a completely black head and a cheek longer than broad. They nest on the surface or aboveground, occasionally underground. Nests may be found in haystacks, abandoned mouse nests, or birdhouses. They are said to be one of the more aggressive species, most likely when nests are disturbed.
Yellow-Fronted Bumble Bee - Bombus flavifrons
|Bombus flavifrons female|
Bombus flavifrons females are usually characterized by yellow and black hairs intermixed on the face, and intermixed yellow and black on the anterior of the thorax. The first two tergite have yellow bands while the third and forth tergite have either orange or black. The forms I've seen at Vesper Meadow usually have black bands with few orange hairs intermixed, appearing dull orange. Similar to californicus, they have a relatively long cheek (malar space longer than wide).
|Bombus flavifrons male|
In contrast to females, male flavifrons are almost entirely yellow or sometimes have black or orange hairs intermixed in the last few tergites. This species nests primarily underground, utilizing abandoned rodent burrows.
Fuzzy-Horned Bumble Bee - Bombus mixtus
Bombus mixtus has yellow and black hairs intermixed on the face and thorax. The first abdominal tergite is always yellow, followed by a black band and the fourth/fifth tergites orange, sometimes appearing dull and intermixed with yellow hairs. B. mixtus is sometimes known as the fuzzy-horned bumble bee because the males have tufts of hair jutting from their flagellum (segments of the antennae), though they're only visible at certain angles under magnification. They are flexible in their nesting locations, nesting above- and belowground.
Black-Tailed Bumble Bee - Bombus melanopygus (syn. edwardsii)
|Bombus melanopygus (syn. edwardsii)|
As seems to be the case with many of the Western bumble bees, Bombus melanopygus has two distinct color morphs. The morph pictured here has no orange, and is sometimes considered a separate species, B. edwardsii, depending on the authority. The black-tailed bumble bee, B. melanopygus, is so named since the last tergite is always black. The hairs on the head are usually yellow or yellow intermixed with black. Similarly, the anterior of the thorax is mostly yellow with black intermixed, followed by a black band, with yellow hairs on the thorax posterior. Note that the corbicular fringes are mostly black (compared to vancouverensis nearcticus which has orange corbicular fringes) The abdomen always has yellow on the first tergite, usually followed by orange on the second and third tergites.
|Bombus melanopygus (syn. edwardsii)|
Nevada Bumble Bee - Bombus nevadensis
|Bombus nevadensis queen|
Bombus nevadensis is similar to B. griseocollis which is more common at lower elevations. B. nevadensis has a look of being clean cut. It seems more brown than yellow compared to other bumble bees in the area. Hair on the face is usually black, sometimes with a few yellow hairs intermixed. There is usually a black spot or band between the wings with many intermixed yellow and black hairs around it. The sides of the thorax are black. The second and third tergites always yellow, while the first tergite is either black or yellow. The last few segments are always black, except for males which have orange at the tip. These large bees are most often ground nesters.
Two-Formed Bumble Bee - Bombus bifarius s.l. (syn. vancouverensis nearcticus)
|Bombus vancouverensis nearcticus (syn. B. bifarius s.l.)|
|Bombus vancouverensis nearcticus|
Bombus vancouverensis nearcticus has a characteristic black notch in the center of the yellow band on the posterior of the thorax. There is a yellow band on the fourth tergite while the fifth and sixth tergites are always black. Compare with edwardsii (syn. melanopygus) which has yellow on the sides of the fifth tergite. This species will also have orange fringes on the corbicula while edwardsii will usually have black hairs, sometimes tipped with orange. The two-form bumble bee is primarily an underground nester, though they occasionally nest on the surface.
Yellow-Faced Bumble Bee - Bombus vosnesenskii
(including descriptions for vandykei and caliginosus)
- - -
Thanks for taking the time to read this. This is no substitute for a proper identification guide, but rather an attempt at an introduction. I hope you can make it to the 2021 Bumble Blitz, so if you can please RSVP!
Learn more about Bumble Bees:
PNW Bumble Bee Atlas (Website)
Genus Bombus - BugGuide.net (Website)