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bumblebee 101, with leif richardson

bumblebee in geranium phaeumI CAN IDENTIFY A LOT OF PLANTS, and I’m pretty good with my local bird and frog species, but a landmark book has me putting down my trowel every time someone buzzes by and having a careful look at bees–especially bumblebees. The book is “Bumble Bees of North America: An Identification Guide,” and one of its four esteemed co-authors, Leif Richardson, joined me for a bumblebee 101 on the radio. Get a closer look at bees, and maybe win the book, too.

Richardson, who got his doctoral degree in the Department of Ecology and Evolutionary Biology at Dartmouth College and is now an ecological consultant and post-doc candidate, created “Bumble Bees of North America: An Identification Guide,” for Princeton University Press with Paul Williams, Robbin Thorpe, and Sheila Colla. As you’d see in a field guide to birds, range maps for each species are included, along with sections on natural history and conservation and even a glossary with up-close images of bumblebee body parts and more.

Among the “aha’s” of our conversation: That bumblebees (bees in the genus Bombus) are like the annual plants in our gardens, performing their whole life cycle by summer’s end. That they can sting, and do make honey—but a lot less than, say, honeybees. And that you can learn to ID probably half the ones in your garden, even if you’re not a scientist.

I’ve transcribed the high points in the transcript that follows, or listen to the whole interview using the player below.

 

my bumblebee q&a with leif richardson

Bulble Bees of North America coverQ. First, can we briefly place bees, and bumblebees, in the order of things?

A. Bees are in the insect order called Hymenoptera, which also includes ants, wasps, sawflies and a few miscellaneous taxa. The closest relatives of bees are wasps, and they diverged from them many millions of years ago.

Q. Yes, I read in the book that bees evolved from wasps 100 million years ago—though frankly, I can’t tell the two apart. Are there things I can be looking for?

A. What many people consider a bee is the furry thing that looks like a honeybee, but most people don’t know that there are many species of bees that closely resemble wasps.

In general, bees are more hairy than wasps, and the hairs are branched—all bees have branched hairs at least somewhere on their body. They can sometimes look very feathery under the microscope, just like a bird feather….The feathery hairs insulate, and also aid in the collection of pollen—or so is the theory.

In most bees, the females collect pollen to feed to their offspring, so they have a pollen-carrying structure. We call that a scopa—which is usually a morphological characteristic of the exoskeleton combined with hairs. If you think of what a honeybee’s leg looks like, you have that big, wide area on the hind leg—this is the scopa of a honeybee. It’s a concave area and then it has long hairs that arch over it, so the bee can pack pollen in there.

In other bees, the scopa may be on the underside of the abdomen or on the thorax, and some bees even carry pollen internally.

You won’t always be able to tell bees and wasps apart, but look for the pollen-carrying structures, and generally more hair on bees than on wasps.

Q. How many kinds of bees in North America? And how many are bumblebees by comparison?

A. There are only 46 species of bumblebees, which are in the genus Bombus, on the continent–but nearly 4,000 species of bees total, including the bumblebees, in the United States.

Most of the bees are not what you know as a bee—most of them are solitary in their lifestyle, and not social [like the familiar honeybees]. So the males and females mate, and then the females go off and lay their eggs in a nest, and provision it with pollen and nectar and seal it up and they’re done.

That’s as opposed to rearing their offspring, and then successive generations of a worker caste coming and later reproductive individuals, too, all in the same colony in the same year—that would be a social bee.

Q. So honey bees—with their hives—those are the most obvious examples of social bees. But bumblebees are social, too—though in a different way, aren’t they?

A. Honeybees are not native to North America, but were imported in the 18th century by Europeans as an agricultural animal, because they are very useful as pollinators, and because they make honey and wax. They are highly social.

Bumblebees are native here and in the rest of the world in temperate and montane places, with a few exceptions. They’re social, but they’re not considered to have as complex a social structure as honeybees. There is a caste system, an they have a reproductive female who we tend to call a queen, and non-reproductive or un-mated females who we call workers who generally do the foraging and caring for their brothers and sisters, and then there are reproductive individuals who are males and new queens—ones who have not mated yet.

Q. Do bumblebees make honey?

A. The other distinction between honeybees and bumblebees is that bumblebees don’t make much honey. The reason is that they are annual—like an annual plant in your garden. The colony does everything by the end of summer, and then dies out. The only individual from the colony who survives is a mated female. All the males die, all the workers die, and the queen who founded the colony dies.

Just the mated females overwinter, and they have no need to store resources because they’re hibernating. With honeybees, you have this feeding that goes on all winter, inside the hive.

Q. Can bumblebees sting?

A. They can, and they do. They are not particularly dangerous unless you are allergic to their stings, and they’re reluctant to sting—unless you are close to their nest.

copyright Princeton University PressQ. How do mated females ever survive a Northern winter? [Bumblebee life-cycle illustration, above, by Ann Sanderson, including the mated female hibernating, is from the new field guide.]

A. It’s pretty amazing. We know relatively little about their overwintering. It’s very hard to find them going to their hibernation spot, and there are very few studies on it.

Here’s what we do know: They tend to go to places that aren’t going to heat and cool rapidly on a daily basis in winter. Often north-facing slopes in forests; places other than out in the open in a field.

They dig a hole, or sometimes they use an abandoned rodent cavity or other existing hole, and they probably would use walls of building. They spend the winter in a hibernating state, and they do have food reserves in their bodies that they are consuming, slowly.

Starting sometime in April in the North, they’re starting to look for their nest sites, so you will see them flying around near the ground and then landing, and flying again a little ways and then landing. They’re often searching for a nest site and investigating holes in the ground.

Q. The book states that one of its primary aims is to make the process of ID’ing bumblebees as straightforward as possible…but bumblebees are not so easy to tell apart. Even a prominent bee expert quoted in the book called bumblebees, “morphologically monotonous.” Is it possible to give us a very high-level 101 on looking at bumblebees with a sharper eye?

A. The key word you said is “look”—meaning pay attention, and to spend as much time as you can observing them. Pay attention to their structure, and their behavior. It’s a little bit like birdwatching—at first it is a little overwhelming, with so many color patterns and body sizes. This is a little harder, though, since they’re smaller, and scientists sometimes need to “destructively sample” to really know which species is which.

But you can learn to identify perhaps half of the bumblebees in your area without catching them.

Pay close attention to the color patterning of the three different body segments—the head, the thorax (the middle segment, where the legs and wings are attached), and the abdomen. Also pay attention to the body shape. In the book we explain how to tell males from females, and workers from other females.

I will say this: color patterning is not enough to identify them in all cases, and often you have to look at the morphology of the face. The shape of the eyes, the distance from the top of the eyes to the bottom of the eyes, and so on.

copyright Princeton University PressQ. I love the very graphic bumblebee illustrations and range maps in the book—they look like maritime “signal flags” to me, bold, simple patterns.

A. In the book, we talk about these groups of species that are very similar. So if you start noticing that some are half-yellow and half-black, you’ll see that in contrast to the ones that have stripes of yellow-black, yellow-black-and then some include an orange stripe.

Then you can try to identify which of the several with orange stripes it is.

Q. I love learning new words, and from you I have learned aposematic. Can you define it for us?

A. Aposematic means when animals have a warning coloration, so they have adapted to have a color pattern and also a suite of behaviors that tell potential predators that they are dangerous.

This is common in nature: the monarch butterfly caterpillar, and the adult butterfly—things that are orange and black, like the coral snake that is black and yellow and red. These are color patterns that are either understood on an innate level by predators or a learned level.

Many bees are yellow and black, perhaps with red or orange, and many of their main predators are thought to be birds. Birds don’t innately know that bees are dangerous, but after sampling one bee, studies have shown that birds such as blue jays will never eat another thing that is furry and yellow and black again.

Q. I’d hoped to have time to talk about the chemicals called neonicotinoids and the negative effects they are having on bees and other creatures, but we’ll have to do a separate Q&A on that.

A. Bee declines are being driven only in part by use of neonicotinoid pesticides. There is convincing evidence that these chemicals reduce bee fitness and can drive bee declines, but there is a lot of dispute over the relative importance of this one factor. I think we have all the evidence we need to call for drastic changes to the way pesticides are used in agriculture, but not everyone agrees.

You may want to look for mention of this in the European press: As the EU countries are more progressive in their approach to pesticide regulation, there is more pressure on the chemical companies, and tempers flared last month over whether particular scientists lack objectivity because of their relationships with the producers of neonicotinoids.

Q. More to come on that. Thank you, Leif.

enter to win the field guide

Bulble Bees of North America coverI’VE BOUGHT AN EXTRA COPY OF “Bumble Bees of North America: An Identification Guide,” from Princeton University Press, to share with you. All you have to do to enter is answer this question in the comments box way down at the bottom of the page–after the last reader comment.

bumblebee detailWhat aspect of my conversation with Leif Richardson about bumblebees surprised you most–which “aha,” or did you know all this about bumblebees?

No answer, or feeling shy? Just say, “Count me in” or something like that, and I will–but I am interested to hear if you are learned as much from him as I did. I’ll pick a winner after entries close at midnight Monday, June 9; U.S. and Canada only. Good luck to all.

more from leif richardson, and about pollinators

(Illustrations of range map and life cycle from “Bumble Bees of North America,” Princeton University Press. Amazon affiliate links yield a small commission, which I use to buy books for future giveaways.)

prefer the podcast version of the show?

MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 10th year in March 2019. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. This segment is a replay of a show first recorded in June 2, 2014. You can subscribe to all future editions on iTunes/Apple Podcasts or Spotify or Stitcher (and browse my archive of podcasts here).

  1. cappy says:

    I did not know that bumblebees hibernate or that they are native and honeybees are not! So interesting. Thank you!

    1. Babette says:

      I didn’t know that bumblebees spend their lifetime over the summer and then all die except the mated female! I have a very peculiar what I think is bumblebee that actually hovers over my Esperanza plant. It is very fast and darts back and forth. Love nature!!

  2. Mary Buzzell says:

    Wow. Didn’t know any of this information. I didn’t know they all died off except for mated females at the end of summer. Sort of sad. Would love to have the book to read more. I am trying to plant more bee friendly flowers in my yard.

  3. Stacy says:

    A few years go my partner made a wood mobile out of downed weathered wood from a local lake here in Utah. We hung it outside our back door in a fairly sheltered space and since then it has become the most wondrous place to watch bumble bees bore into. There are holes all over it, we have seen all black, black/yellow and black/yellow with orange. We have become obsessed with “who is coming this year” to nest in our mobile. This year there have been 2-3 vying for spots and they have become somewhat territorial about it. We have speculated on the bees, but really no nothing about them. This podcast has been truly enjoyable as we both learned a lot about them, the fact that they can sting, the colony die off and the fact the one mated female will hibernate. Thank you as always!

  4. Dianne Short says:

    I did not know the word “aposematic”, although I did know about coloration as a warning signal.

  5. Clare Beelman says:

    So glad to hear his answer to your question about what and where bumbles overwinter. I’ve been wondering about this myself. I’m surprised to hear that little is known about bumble hibernation behavior.
    Thank you for highlighting this new book.

  6. Rich Hill says:

    I really enjoyed this episode. If I heard right that Lief is working on an advanced degree, that’s amazing. He knows so much and there was so much that he wanted to convey, please have him back. My sister in law does research at Oregon state university on how and if the timing of pesticide application makes a difference on how it affects the honey bees. So the part that caught my ear was that bumble bees self medicate. I wondered if offering these compounds to the commercial hives would help.

  7. Tammie says:

    I’ve only known for a few years that honeybees weren’t native. I didn’t know, however, that a mated female bumblebee hibernated. Interesting!

  8. Julie says:

    Amazed by the over wintering and life cycle of the bumble bee. Looking forward to id’ing them this summer in my garden.

  9. Nancy Wyatt says:

    Love the bumblebee.I hope they survive here in Minnesota. It has been a cold spring and we are going to have frost here tonight. Thanks for the great information as always

  10. June says:

    I didn’t realize bumblebees were social or that the only survivor to overwinter was one mated female. hmm, lots to think about.

  11. Mary Ann Baclawski says:

    I was especially interested in the life cycle information. I noticed a bumblebee snuggling in a dirt hole in my yard a few days ago and wondered if it was establishing a winter nest. Probably not because it was too exposed according to this talk.

  12. Mel says:

    They’re such hard workers. Out early in the morning and late in the day. I do every thing I can to attract them to my gardens.

  13. Glenda says:

    The book will inform a lot of questions about the bumblebee. I look forward to reading it, we have noticed a ground nest here in the center of a clump of ornamental grass and were surprised to see the, entering and leaving the site.

  14. Anne says:

    I am very fond of most insects (and trying to learn not to hate the others, with the possible exception of fire ants), and I love bees. However, the only bee I can identify is the carpenter bee. I would be so happy if I could learn to identify even half of the bumblebees I see!! Until I read this transcript, I didn’t know that most bumblebees are “annuals,” with only fertilized females surviving the winter. Makes their little lives even more precious.

    1. Deborah Martin says:

      I didn’t know that the color patterning of the body segments are not always enough to identify them. I like they need to be looked in the eye to confirm ID! Also love learning they are foraging for their own health care if needed. Thank you for the exceptional interviews you offer us!

  15. Karen Reynolds says:

    I did not know the word “aposematic”. As a bee keeper, and seeing bumble bees each year, this book sounds very interesting.

  16. Ann Johnston says:

    Now I know why I hound a big fat bee in the hole I was digging to plant a seedling. I disturbed her sleep mode.

  17. Hal says:

    I was fascinated by Leif Richardson’s research and the relationship between pollen and bee parasites. I still don’t really get it, and may have to listen again. But who knew ? (besides Leif)

  18. Donna Pike says:

    Oh my, I had no idea that bubmlebees lived only one season. I love to see them in the garden, especislly early in spring. Some of them are HUGE! This book sounds fascinating. Would love to give it s good read.

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