Bumble Bee 101

While both bumble bees (Bombus species) and honey bees (Apis species, mostly A. mellifera for beekeeping) are social insects and share some similarities in their life cycles, there are also significant differences. 

1.  Colony size and location: Bumble bee colonies, typically containing up to a few hundred individuals, are located underground. Honey bee colonies are much larger (with thousands to tens of thousands of individuals), and are located in tree hollows and hive boxes.

2.  Annual vs perennial colonies: Bumble bee colonies are typically annual, lasting for only one season. Each colony is initiated in the spring by a single queen born in the previous season, which then hibernated during winter. In contrast, honey bee colonies are perennial, capable of surviving for multiple years. The queen honey bee can live for several years, unless superseded by a new queen.

3. Queens: While it is extremely rare to witness honey bee queens outside of beehives, bumble bee queens, typically much larger than workers, can be observed on various flowers, especially in early spring and late summer. They feed on nectar and, at times, carry nectar and pollen back to the colony.

4.  Males (drones): While honey bee males eat nectar/honey stored in the hive, bumble bee males can be observed on various flowers, feeding on nectar. However, they do not bring back nectar or pollen to the colony (they never return to their birth colony).

5.  Foraging distance: Bumble bee workers do not fly very far from colonies compared with honey bees. Actual numbers vary greatly among species, colony sizes, and environments, so I'll provide just one example for each. In a study conducted in the UK, the mean foraging distance of Bombus terrestris was 267.2 m (with a maximum of 800 m) (Stephan Wolf and Robin F.A. Moritz, 2008).  In contrast, during a study conducted in Germany from May to July, the mean foraging distance of honeybees was 1,500 m (reaching a maximum of 10,037 m) (Ingolf Steffan-Dewenter and Arno Kuhn, 2003). 

6. Tongue (proboscis) length: Some bumble bee species have much longer tongues than honey bees, enabling them to access nectar from plants with deep floral nectaries.

7. 'Buzz pollination': The anthers (the male part of the flower) of certain flowers, such as tomatoes and blueberries, tightly hold onto their pollen. Bumble bees can facilitate the release of such pollen by grasping the anthers with their legs and vibrating their flight muscles.

8. Floral fidelity: Honey bees generally exhibit high floral fidelity, meaning they tend to visit only one species of flower per foraging trip. In contrast, bumble bees are less selective and are more likely to visit flowers from multiple species during a single trip. As a result, it is not uncommon to observe two bumble bee workers on the same plant carrying pollen of different colors. For example, in the photos below, two yellow head bumble bee workers were foraging on a patch of broadleaf lupine. The worker on the left carried reddish pollen (the expected color for lupine), while the worker on the right carried off-white pollen, indicating visits to a different plant species earlier in its trip.

These illustrations, shown in  Bumble bees of the Western US, depict the anatomical features of female bumble bees. They serve as visual aids for understanding and identifying the distinctive characteristics of different bumble bee species.

Bumble bee queens are larger than workers, and generally observed foraging alone. They are found early in the season before worker bees emerge, and late in the season. Bumble bees on early spring flowers like crocus, are queens. Bumble bees found in November are queens (with exception of workers from rare fall-winter colonies). A bumble bee on the ground digging a hole is definitely a queen.

Male bumble bees (drones) usually emerge later than workers. They do not carry pollen, nor do they sting. In some species, males show significantly different color patterns as shown in the photo below, while in others, the gender difference in color is very subtle or nonexistent. Generally, males appear hairier than females. As shown in the illustration below, provided on the Bumble Bee Watch website, males possess longer abdomens, longer antennae, and thinner legs than females, although these features can be challenging to discern in the field.

Some fly species show bumble bee-like body shape and coloring, but their eyes are larger, antennaes shorter. Photos below show Merodon equestris (narcissus bulb fly).

There are at least 46 species of bumble bees in the US, and you may encounter a dozen or so in your local area. Register in Bumble Bee Watch, and search bumble bee sightings (verified by experts) in your area. I searched King, Snohomish, Pierce, and Skagit counties of Washington State, and found 16 recorded species. You may also be able to find local guides to bumble bees. In my case, Pacific Northwest Bumble Bee Atlas and Bumble Bees of Washington State, and Bumble bees of the Western US, have been very helpful. Bugguide.net also helped me identify bumble bees and other insects that look like bumble bees. 

The illustration below, crafted by Pacific Northwest Bumble Bee Atlas, showcases the color patterns of female (worker or queen) bumble bees. Keep in mind that a particular species may manifest two distinct color variations depending on its geographical location, and male bees can exhibit notably different appearances (visit Bumble bees of the Western US to view color patterns of males). In Puget Sound Lowlands (mostly North Seattle area), I've regularly  encountered five species, highlighted within blue rectangles. In rare occasions, I have seen four more species highlighted in yellow.

Click to view each species or group

Bumble bee species frequently found in Puget Sound Lowlands (mostly in North Seattle area). 

1. Black-tailed bumble bee (Bombus melanopygus) is the most colorful species with red/orange abdomen. This species may establish fall-winter colonies.

2. Fuzzy-horned bumble bee (Bombus mixtus) has orange hair at the end of the abdomen.

3. Yellow head bumble bee (Bombus flavifrons) has a very long tongue. In my area, females are typically yellow and black, although a very few individuals may show some orange on the abdomen. Males are mostly yellow.

4. California bumble bee (Bombus californicus) is another long-tongued species. It is listed as the yellow bumble bee (Bombus fervidus sbsp californicus) in the illustration above. In my area, females are mostly black with yellow stripes, and males are yellowish. 

5. Yellow-faced bumble bee (Bombus vosnesenskii) is the most numerous bumble bee, especially later in the season. It has a mostly black body with yellow face and a yellow stripe on the abdomen (males may have two stripes). It forms what is called the 'yellow-faced group' with the similar-looking obscure bumble bee.

Uncommon bumble bee species in Puget Sound Lowlands (mostly in North Seattle area). 

1. Obscure bumble bee (Bombus caliginosus) makes up the so-called 'yellow-faced group,' alongside the similar-looking, much more common yellow-faced bumble bee. What I saw in my neighborhood may actually be this species, or a variation of the yellow-faced bumble bee.

2. Common eastern bumble bee (Bombus impatiens)  is not native to the Western US, but escaped from greenhouse pollination. 

3. Cuckoo bumble bees, such as Fernald cuckoo bee (Bombus flavidus) and indiscriminate Cuckoo bumble bee (Bombus insularis), do not have their own workers but instead hijack established colonies of other species.

4. Sitka bumble bee (Bombus sitkensis) is rare in my neighborhood, but regularly found at higher elevations.

Other bumble bee species. 

1. Two-form bumble bee (Bombus bifarius) is a high-elevation species that I have never seen in lowlands.

2. Western bumble bee (Bombus occidentalis) has suffered severe population decline in the past several decades, and I have seen it only once in a mountain foothill.