This is an offshoot from another article I wrote. Bugs are good!
I’m fascinated with Bumble Bees. Since we replaced our front lawn with mostly California native plants – now almost 15 years ago – I can’t wait for January when our first manzanitas start blooming — and there they are. Bumble Bees! Because they can tolerate inclement conditions, Bumble Bees (Genus Bombus) are the first native insects I notice.
It also helps that they’re clumsy, large and slow fliers, so easier to see than the mostly tiny native bees flitting about.
Even the brief times it stopped raining, a half dozen Bumble Bees came back to work the manzanitas, packing the pollen on the hairy bristles on their legs to take back to the nest. According to Leif Richardson, a conservation biologist with the Xerces Society, manzanitas are often the first blooming plant here in California as the female worker bees come out of hibernation.
Leif also said that like desert wildflowers, some Bumble Bees stay underground for years.
I feel lucky to live in California, one of the top five states for bee diversity, with 25 Bombus species. They are critical pollinators, and normally compete with the ubiquitous European honeybees. Another reason I celebrate seeing them is they’re declining, with 1/4th of their species at risk. Why? Leif says climate change, pesticides, pathogens and habitat loss, plus honeybees are outcompeting them.
All you wanted to know about Bumble Bees
I asked Leif Richardson some questions about Bumble Bees (technically it’s two words but bumblebee is often used), and about bees in general. See below for his answers, edited slightly for brevity.
Q: NESTS? We’ve discovered nests for many a species in our habitat-friendly yard – numerous birds, alligator lizards and rabbits – but where would the bumblebee nest be?
Leif: Bumble Bees generally travel less than a kilometer to forage, and mostly stay considerably closer than that, so the nest(s) may be in your yard, or at least, your neighborhood. According to the Xerces Society, “Bumble bees like to nest in pre-existing cavities that provide insulation and protection from the elements, such as old rodent burrows, bunch grasses, and as you may have found out— man-made structures, like bird houses, insulation, or even the cotton batting of old furniture.”
Q: BEST PLANTS – I see them first on our California natives, first manzanitas, then our Ceanothus, but then I see them on our Pride of Madeira, a Mediterranean plant. What are the best plants to have to attract Bumble Bees?
Leif: Bumble Bees generally prefer native plants, but yes, they do use non-natives too. They are considered generalists. Pride of Madeira is a popular one. Below are top host plants from last year’s California Bumble Bee Atlas for all of California plus some additional ones they favor in Southern California.
Top Host Plants – Most are CA natives. Non-native plants are noted below.
- Cirsium (Thistle – both native and non-native)
- Lupinus (Lupine)
- Monardella (Coyote mint, Desert Mint….)
- Phacelia (over 125 species in California)
- Agastache (Hyssop)
- Solidago (Goldenrod)
- Penstemon
- Stachys (Hedgenettle)
- Angelica
- Ericameria (Rabbitbrush)
- Eriogonum (Buckwheat)
- Salvia (sages)
- Vicia (Vetch (both native and non-native)
- Eschscholzia (California poppy)
- Senecio (Groundsel – both native and non-native)
- Trifolium (Clover – both native and non-native)
- Acmispon (Deerweed)
- Carduus (Thistle – non-native)
- Lavandula (Lavender – non-native)
- Symphyotrichum (Aster)
OTHERS: Because of the timing of the survey, Leif said Arctostaphylos (manzanitas) and also Arbutus (madrone) are important winter flowerers and very popular with Bumble Bees along the coast. Others in Southern California include Ceanothus (wild lilac), Duranta (verbena – native in Southern Florida), Gaura (Beeblossum – native to No America), Echium (non-native, many are invasive – includes Pride of Madeira) and Fuchsia
Q: HARDINESS – This year we’ve had quite a bit of rain. In early January it was in the 40s and a half dozen bumblebees would show up once the rain stopped, and had the blooms to themselves – no other natives and no European honeybees. Are these the first female worker bees that you’ve talked about?
Leif: Yes, Bumble Bees will forage at lower temperatures than honey bees, so you can find them out even in the low 40s F.
Your photo is a worker Bombus melanopygus (or black-tailed Bumble Bee). This means that their moms were foraging and establishing the nests in December. This species emerges mid-winter on the West Coast in mid-winter, I think to take advantage of manzanita and other winter-flowering shrubs. You may also see B. vosnesenskii (one of many species of yellow-faced Bumble Bees) workers, but they arrive a bit later than melanopygus.
The single most important thing [people can do] is to plant native plants.
Leif Richardson, Xerces Society
Q: HELPING THEIR DECLINE – Why are Bumble Bees declining, and what can people do to help?
Leif: Bumble bees are declining due to a number of threats, and people can help with any and all of these. The single most important thing is to plant native plants. Bumble Bees are losing habitat, so planting appropriate forage plants is the easiest thing one can do to help. They also need nesting and wintering sites, which aren’t always available.
People who want to help bees should consider giving up personal use of pesticides and buying organic food. Climate change is a driver of declines for some species, and I like to tell people they should think about what they can do for bees in this context (lots of possibilities!).
…honey bees are a non-native farm animal brought here from Eurasia that is a threat to wild bees. Honey bees compete with wild bees for food, and also infect them with pathogens through shared use of flowers.
Leif Richardson, Xerces Society
Honey bees are important as pollinators of some crops, but they do not belong on any land where biodiversity conservation is a goal. it’s important to stress that honey bees are a non-native farm animal brought here from Eurasia that is a threat to wild bees. Honey bees compete with wild bees for food, and also infect them with pathogens through shared use of flowers.
Q: OTHER POLLINATORS – Can this info apply to other native bees and to other pollinators?
Leif: This applies only to Bumble Bees in my view, but you could generalize this to other flower visitors, especially other native bees. In a functional sense, bees are much more important pollinators than any other taxon–that is, they accomplish the vast majority of plant pollination…. Bees that are doing the heavy lifting in both wild and crop plants.
Other pollinators (birds, butterflies, bats, flies, wasps, …) have quite different life histories and are going to have a different set of stressors that I don’t think you can just include under the Bumble Bee heading.
Sigh: Proof today (September) that we still have Bumble Bees – this orb spider has a huge meal with this B. melanopygus (black-tailed Bumble Bee)
More info/Resources:
COMMUNITY SCIENCE – Participate at Bumble Bee Watch by reporting your sightings
The life in the nest: During a California Native Plant Society talk on Living with Bumble Bees in 2022, John Whittlesey, owner of Canyon Creek Nursery and Design in Oroville, CA, explained that the Bumble Bee’s goal is to produce as many new queens as possible. “The queen emerges from wintering to forage and search for a nest site, and then makes a brood storage, laying eggs on a mass of pollen. The larvae feed on the pollen for two weeks before spinning a cocoon, then after two weeks pupation the adult bees are female worker bees. At some point in season the unfertilized eggs become adult males. The queen stays in the nest and is attended by worker females.” Any fertilized eggs laid after this become queens, who feed heavily and then hibernate underground — and the cycle continues!
Summer hibernation: In our Inland California yard (Redlands CA) I stop seeing Bumble Bees in summer. Dr. James Strange, Entomology professor at Ohio State University, said In areas with high summer temps (above 95F for a Bumble Bee) there is often a long period of summer aestivation, which is hibernation but in hot weather. “The queen bees that found the nests will go below ground and go dormant until cooler and wetter weather return. Because Bumble Bees live in colonies they require a lot more food than your average solitary bee, so this dormancy in the heat allows them to focus their lifecycle on when the floral resources are most abundant.
For more info on other native bees and pollinators – see “Helping our Native Pollinators”
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