bumblebee 101, with leif richardson
I 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
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.
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.
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
I’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.
What 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
- Visit Leif Richardson’s website
- What I learned about pollinators in 2018
- Pollinator plants, with Xerces Society
(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).