Saturday, October 9, 2010

Saluting an Arctic Pioneer

The Northern Bumblebee, Bombus polaris, can survive on Ellesmere Island in Canada's far northern arctic. This is the farthest north that any true social insect can live. This species is a true northerner, being found in a circular distribution around the arctic, ranging all the way from Alaska, to Greenland, Scandinavia and northern Russia right across to the Bering Sea.

The Northern Bumblebee is an important pollinator of the short-lived arctic flowers, visiting the blossoms of Arctic Poppies, Arctic Roses and Arctic Willows. It is one of the few pollinating insects that is sufficiently well insulated with a furry coat to brave arctic temperatures. And like all bumblebees, the Northern can vibrate its thoracic muscles to raise its body temperature to 86 degrees F. or higher. It can also sit in the center of an Arctic Poppy, and using the petals like a parabolic solar reflector, absorb more heat from the sun than if it sat on a leaf of the plant. Finally, B. polaris has apparently adapted to arctic conditions by developing the ability to maintain better control over the temperature in its abdomen, holding it several degrees warmer than in temperate zone bumblebees.

On October 12, 2007, Canada Post recognized this beneficial arctic pioneer by issuing a 5 cent stamp in its honor. The bee is shown busily foraging on a flower head of Red Clover. Could this be an error promulgated by the Canadian postal system? Does Red Clover extend into the high arctic?

Well most bumble bees certainly seem to love Red Clover. And this important agricultural crop plant, introduced into North America, is apparently found as far north as James Bay. But it probably does not extend into the high arctic. All is not lost, however, for the range of the Northern Bumblebee in Canada extends well south of James Bay in Ontario. So Bombus polaris could well indeed feed on Red Clover flowers, and probably does whenever it can find them.

Much thanks to Nativeplantgirl for finding and passing along these wonderful stamps.

Monday, July 5, 2010

Bee Briefs #2: Bumblebees In The News

Traveling bumblebees bring trouble (parasites) home; Yellow-banded Bumblebee recovering in Vermont

Commercially reared bumblebees being used increasingly to pollinate field crops like watermelons & sweet peppers

Arctic Bumblebees Still Need Beauty Sleep; retain circadian foraging rhythms even in 24-hour daylight

New congressional Pollinator Protection Caucus to champion the cause of bees in Washington & promote research

Xerces Society Seeks To Add Franklin's Bumblebee To Endangered Species List; only one seen since 2006

Report on conservation genetics, foraging distance & nest density of the scarce Great Yellow Bumblebee in UK

12 Nectar Cafés for bees planted and maintained by local school children, part of Pride in Londonderry initiative

International Conference on Pollinator Biology, Health and Policy, July 24 – 28, Penn State University

Increasingly common badgers said to threaten bumblebee populations in UK; they dig up nests and eat the brood

Two cuckoo bumblebees: specialist Bombus vestalis & generalist B. bohemicus use different odor cues to find their host B. terrestris

Bumblebee mimic - inquline larvae feed on debris in bumblebee nests - like having a live-in house cleaner!

UK gardeners asked to help in citizen survey of the range of the Tree Bumblebee; part of insect & wildlife week

[Photo by D. Barr]Link

Monday, June 28, 2010

A Bumblebee Workshop

I attended a bumblebee workshop on the weekend. Our session leader was Sheila Colla, a grad student at York University and an internationally known expert on North American bumblebees. The event was held at the Evergreen Brick Works, a unique, re-naturalized habitat and education center in Toronto, Canada.

Right: Sheila Colla uses a plastic vial to trap a bumblebee for observation.

The workshop dealt with the life history and biology of bumblebees. And we heard about the pollination services these fuzzy, black-and-yellow bees provide. Colla placed particular emphasis on the decline of a number of key bumblebee species in Eastern North America, in particular that of the the Rusty-patched Bumblebee, now on the edge of extinction. In fact it was Colla's own research that demonstrated beyond doubt the sad situation of this once common species.

Our workshop leader provided a handy guide to the color patterns of some of the most common local species. She also gave us the opportunity to view museum specimens so that we could see just what the diagrams referred to on real bees.

Then the best treat of all. Colla led us out into the field, to patches of wildflowers in the surrounding area. She pointed out several species, including the Two-spotted Bumblebee and the Red-belted Bumblebee.

We were shown a clever technique that anyone can try. Colla was able to place a plastic medicine vial beneath a bumblebee busily foraging on a flower and then quickly pop the cap on, trapping the bee inside. It was easy for all of us to examine the living specimen, harmlessly confined for a few minutes, while Colla pointed out the identifying characteristics. Once the demonstration was over, the bee was released to go back about its business of pollination.

The workshop was part of the celebration of International Pollinator Week, 2010. Sheila Colla is co-author of a new field guide to bumblebees, expected to appear later this summer. I'll be one of the first to start using it as soon as it's available.

You can learn more about Colla and her work on her website:

Friday, June 25, 2010

We Need The Bumblebee

Last evening, in Toronto, a swinging group called the 'Raging Grannies' gave the world premiere performance of a new song about bumblebees. The 'Grannies' had the audience at a 'Pollinator Cabaret' held at the Gladstone Hotel clapping time and singing along - they brought the house down. The event was held in celebration of International Pollinator Week.

With the hope that others will sing in praise of the bumblebee this Pollinator Week, here are the complete lyrics of the new song:

We Need The Bumblebee
(to the tune of The Blue-tail Fly)
Words by Dave Barr

The winds, the woods, the skies are free
The world of earth and the world of sea
There's fruit in the garden for you and me
But not without the bumblebee

People need fruit and veggies too
People need fruit and veggies too
People need fruit and veggies too
We need the bumblebee

Each bloom in the garden is colored fine
Each smells so good upon the vine
To spread some pollen both far and wide
It calls the bumblebee inside


The bumblebee's got pretty hair
With black and yellow stripes so fair
She carries baskets on each flight
To pack the pollen in real tight


The fruit comes from the flow'r you see
That's healthy food for you and me
Flow'rs need pollen so the fruit can grow
The bumble's visit makes it so


The bee starts early on her run
Before the world warms in the sun
She gathers nectar and pollen food
Takes them home to feed her brood


The bumble's home is in the ground
An empty mouse nest she has found
She raises daughters who can't wait
To help her fly and pollinate


Poor bumblebee she's under threat
We hit her with the worst things yet
Disease and nasty pesticides
And take her habitat besides

[skip Chorus]

8. (slowly)
We've got to save the bumblebee
Her fate is linked to us you see
We need her flight from flow'r to flow'r
To save our food with pollen power!
(last two words shouted out)


[Words Copyleft (Ɔ) by Dave Barr, 2010: Creative Commons Licence. Image from a photo by D. Barr]

Wednesday, June 23, 2010

'Keeping The Bees' by Laurence Packer

Laurence Packer is a bee biologist whose research and teaching base of operations is at York University in Toronto, Canada.

The title of his book, and much of the publicity that has surrounded it suggest that it is about something that many of us have heard a lot about already - the one-two punch of the central role of bees in human food production followed by the spectre of colony collapse disorder and a world without bees. And it is about these things, in part. But this book is so much more.

Unlike many of his contemporaries writing on the same topic, Packer can offer a broad overview of his subject. His global perspective is derived from years of working with many different kinds of bees, hands-on work, observing behavior and biology in the field.

This book is actually a biology of bees, from the tiniest solitary bees to communal, semisocial and eusocial species. It is a biology in the grand tradition of Jean Henri Fabre, the 19th century French polymath whose books introduced the world to the engaging lives of insects.

Bumblebees play a leading role in Packer's narrative. He touches on everything from their life history, to their social behavior and their diseases, parasites and predators. Packer tells us why bumblebees (and indeed all bees) appear to be at greater risk of extinction than other organisms, a topic I'll be expanding on in a future entry in this blog.

Packer isn't afraid to introduce us to some of the specialized terminology that goes along with his field of study (a bee biologist, for instance, is a melittologist). But in general he works hard to keep his story in everyday language. He has a tremendous knack for making even the most complex subjects understandable in human terms. Bees that maintain a communal nest burrow system are just like human condo dwellers, he tells us, with a common entrance and private apartments.

Those who are looking for fresh evidence that we need bees and that bees are endangered will find it here. And there is also advice for those who want to do something to help bees, including the completely original and delightful suggestion of walking on the grass.

Shortcomings? Well, pictures for one. The book has a few photos, but publication costs aside, it could have had so much more. The bee image on the dust jacket is truly unfortunate - a nice bee, but the graphic treatment is not my favorite. But then Packer is writing in the tradition of the great naturalist-authors like Fabre, Willy Ley and Howard Evans. Like these masters in whose company Packer now finds himself, his vivid language alone is enough to create compelling images of his fascinating subjects in every reader's mind.

'Keeping The Bees'
is a must read for any fan of bumblebees.

Bug of The Week

Debbie Hadley, who writes about insects for, has featured a bumblebee this week in honor of National (and International) Pollinator Week.

She nominates a different insect each week for the the prestigious title of "Bug of The Week." The lucky insect starts out as an unknown and Debbie's readers are asked to do their best to identify it. A week later she reveals the insect's name and provides another unknown.

Readers of this blog will have no difficulty recognizing this week's "bug" as a bumblebee. But which one? I don't want to spoil the suspense, so please go to Debbie's bug-of-the-week page, check out her clues, and try your hand at the identification. In a week's time, when Debbie gives the answers to her readers, the solution will be reported here as well.

Have fun.

Saturday, June 12, 2010

Bee Briefs: Recent News About Bumblebees

Join the Global Bee Project and become a Bee Guardian!

International Pollinator Week is coming, June 21-27

Citizen scientists begin 4th year of the Great Pollinator Project, a sort of bee census, in New York City. They monitor some 200 species of bees to study pollinator biodiversity

Regicide and captive virgin queens; 10 things you might not know about the fascinating lives of bees

Researcher developing landscape conservation & restoration guidelines for preservation of native bee populations

BeeWalk to help monitor changes in bumblebee populations; invaluable for conservation

New Zealand Short-haired Bumblebees in restoration project die in hibernation, just before travelling to the UK

Two new bumblebee species settle in Iceland These both appear to be on the move from Europe.

The Tree Bumblebee continues its range expansion in the UK; now in west Wales

Now more bumblebee nests in UK cities, towns and suburbs than in the countryside - that's bad news for wildlife

You can buy black-and-yellow striped socks and help protect bumblebees

[Photo by Brieg, CC License]

Friday, June 4, 2010

A bee or not a bee?

Our title today comes from Chapter 4 of Laurence Packer's new book, 'Keeping The Bees.'

Packer writes about the numerous 'wannabees,' the non-stinging insects that derive protection by looking like dangerous species that can sting. The photo on the right shows the hoverfly, Merodon equestris, pursuing its meal of nectar on a flower of Scabiosa and looking for all the world like some kind of bumblebee.

This kind of mimicry is referred to by evolutionary biologists as Batesian mimicry, named after the English naturalist, William Henry Bates.

The Greater Bulb Fly in the photo is a vegetarian with no sting. Its larvae feed on the roots of garden bulbs like the Narcissus. And the adults, as noted, are flower visitors, subsisting on nectar and pollen. They have no defense against insect-feeding predators like birds. But bumblebees can sting, and birds have learned to leave them alone, or suffer the consequences.

Packer provides a vivid description of the situation of an insectivorous bird. After invoking memories of the pain of a bee sting he writes, "Imagine what it would be like for a small bird or a small mammal to receive the same amount of venom in the tongue or the roof of the mouth... Having attempted to catch a bee to feed its [nestlings] the stung parent [bird] would likely be incapable of catching anything else for a long time. There is a good chance its brood would starve to death while its parent recovered."

Reason enough to avoid anything that looks remotely like a bumblebee. And thus, the harmless hoverfly is allowed to go safely about its business, protected by the fact that it only looks dangerous.

[Photo copyright D. Barr]

Friday, April 9, 2010

Bumblebees Under Glass

I like flowers. The endless variety of form and color are a continuing source of amazement and contemplation. Not surprisingly, I also like to photograph flowers, and I make frequent trips to find new ones to photograph. One of the best places to find flowers, at all times of year, is a greenhouse - one of my favorite places to be.

There are lots of things to see in greenhouses besides flowers. I've seen birds, I've seen moths, and I've seen pillbugs. One of the more surprising things seen during a recent greenhouse visit was a bumblebee. That bee seemed to be touring the various rooms of the greenhouse just like me, looking for new and tempting blossoms.

I assumed the bumblebee had blundered in to the greenhouse accidentally, probably through one of the open vents in the roof. I was not aware at the time that this bumblebee may well have been bred especially for greenhouse duty, and she may have been released in there intentionally.

Why would a greenhouse owner be willing to pay for commercially reared bumblebees to be released 'under glass?' If you are interested in harvesting seeds from exotic plants, you would probably want some bumblebee pollinators around. But that research interest doesn't seem like enough to support a whole bumblebee rearing industry. Only another industry could do that.

In the case of bumblebees that industry is the commercial growing of 'hothouse' tomatoes. Tomatoes have an unusual flower. The petals are fused together into an urn-shaped tube that largely encloses the reproductive structures. The pollen grains are enclosed by the walls of the anthers and can only escape through tiny pores. Now these flowers are self-fertile. The flower can be fertilized by its own pollen, resulting in the growth of a tomato fruit.

Right: Tomato blossoms - a 'difficult' flower.

But the peculiar structure of the tomato flower means that fertilization can only happen if the blossom is jostled, shaking the pollen grains out of the anthers so they can fall on the stigma. Outdoors, a moderate breeze is enough to shake up the tomato blossoms, producing the tomatoes that go to market. But in a greenhouse there is no wind, and that is where bumblebees take over.

The tomato flower does not have much nectar, but it is enough to attract a hungry bumblebee. The bee lands on the flower and proceeds to vibrate its flight muscles, at the same time producing a loud buzz. The vibrations are transmitted to the flower and shake loose the pollen. This 'buzz pollination' is something honey bees cannot do.

So bumblebees have a special talent. Their skill with buzzing 'difficult' flowers has made commercially-reared bumblebees an important factor in the production of the greenhouse-grown tomatoes that eventually show up in our salads and pizza sauce.

[Photo by Niek Willems, CC license]

Tuesday, April 6, 2010

Big Bees and Little Bees

In the bee world, bumblebees are really big. A large queen bumblebee of a relatively large species, like Britain's Buff-tailed Bumblebee (Bombus terrestris) may be up to 22 mm (a little less than an inch) long. Compare that to one of the tiniest bees, the solitary bee, Quasihesma, from Australia, less than 2 mm (around 1/16 inch) in length. This tiny bee could easily sit on the head of a pin.

But bumblebees are by no means the largest bee. In North America, the common Large Carpenter Bee (Xylocopa virginiana) is still larger on average, with a maximum length of 23 mm (just under an inch). These carpenter bees look a lot like bumblebees, and I often have to look carefully to see the metallic-blue, shiny abdomen that distinguishes this species from the furry abdomen of bumblebees.

If you are bee watching in the jungles of Indonesia, you may see the rare Giant Resin-bee, (Megachile pluto), a full 39 mm in length (about an inch and a half). So the largest bee is about 20 times larger than the smallest one, with bumblebees coming out somewhere in the middle.

A large bumblebee queen has to be big, because to keep order in the colony she may have to be tough. Her worker daughters are not always the meek handmaidens to the throne that their station demands. Some of the larger workers may try to take over egg laying, although their eggs can only produce males. Then the queen will have to bully them back to their normal duties.

Bumblebee queens may keep their workers under control, but they don't win all battles in the nest. Cuckoo bumblebee females tend to be stronger and more heavily armored than the queens of colonies they parasitise. When the cuckoo enters the nest a violent fight with the queen ensues. Usually the cuckoo female is the winner and the queen dies.

Size is relative, and bigger isn't better, just different. Big bees are large simply because that size suits them to whatever role they play in the environment.

Sunday, April 4, 2010

The Common Eastern Bumblebee - Impatient for Domination

The first person I spoke to about bumblebees told me that whatever I might see, it would probably be Bombus impatiens, The Common Eastern (or Impatient) Bumblebee (CEB). That seemed hopeful. Gosh, it shouldn't be any trouble at all to know what species I was observing.

Turns out things are not quite so simple as all that. There are actually as many as 25 species of bumblebees occurring in eastern North America. You can never be certain of the species you have unless you become familiar with the identifying features of each of them.

But my informant was certainly right about the pervasive presence of the Common Eastern Bumblebee. The dominant nature of this species in eastern bumblebee communities has been reinforced once again in collections made during 2009 by the USGS Native Bee Inventory and Monitoring Lab .

The data made available by bee biologist, Sam Droege, show that of almost 600 specimens collected in 10 eastern states plus the District of Columbia, 65% of the total were the CEB. In those states represented by more than a handful of specimens, Bombus impatiens constituted no less than 64% and in one instance as much as 77% of the total. This species is certainly the most commonly encountered in the east.

Fortunately the CEB is relatively easy to identify too, at least for females, the queens and workers. They are characterized by yellow pile that covers most of the upper surface of the thorax, often with a black spot in the middle. And they have just a single band of yellow pile across the upper surface of the first visible abdominal segment. The rest of the abdomen is covered with black, furry pile. Unlike many other bumblebee species, there seem to be few different color forms or morphs to confuse the issue.

All in all, a most convenient species on which to begin biological observations - common and easily identified. So be on the lookout this summer for the Common Eastern Bumblebee. It will likely be the first one you see.

[Photo by D. Barr]

Wednesday, March 31, 2010

Gardens for Bumblebees

My good colleague, Maria Kasstan spoke to the Toronto Beekeepers' Cooperative last evening. She had just returned from attending the annual pollination symposium in Guelph. The City of Guelph, Ontario, it turns out, has a very active, city-wide pollinator awareness program. A rallying point for all of this activity is Pollination Guelph, sponsor of the symposium.

Now Guelph has for many decades been home to the Ontario Agricultural College and Guelph University. Lots of bee people work there, with plenty of interest in pollination biology. But that doesn't quite explain it all. An enthusiasm for pollination and pollinator-friendly gardens in Guelph seems to extend through the city council and many branches of city government as well.

Maria kindly gave us a capsule account of what she learned. Her talk was fascinating, especially for someone interested in bumblebees.

Bumblebees, in particular, were mentioned during the symposium, including news of the recent promising sighting of the Rusty-patched Bumblebee in Ontario's Pinery Provincial Park. Also discussed was the relationship between arctic bumblebees on Ellesmere Island and the flowers they visit. Apparently the corolla of the flower serves as a parabolic reflector to concentrate the sun's warming rays. So in that chilly climate, bumblebees visit the flower to keep warm, effecting pollination at the same time.

But the big topic of the day was how to develop gardens that serve as habitat not only for bumblebees, but for all insect pollinators. The City of Guelph, under its Healthy Landscapes program publishes lists of pollinator friendly plants to include in the garden. They cover bee, butterfly and hummingbird plants, sun and shade tolerant native plants, as well as trees and shrubs that provide pollinator resources.

The guidelines for pollinator gardens include:
  • plant plenty of nectar and pollen rich flowers
  • provide food sources (host plants) and overwintering places for eggs and pupae
  • provide water
  • avoid using pesticides and herbicides
  • provide sites and materials for nesting and overwintering
  • reduce your area of lawn grass

Because of monoculture and pesticide use, agricultural areas provide no comfort for bumblebees. So what we do in our cities and in our own gardens may be the best hope for bumblebee conservation.

[Photo by Jina Lee, CC License]

Sunday, March 28, 2010

The Fly and the Bumblebee: Not a Love Story

The Toronto Entomologists' Association invites some great speakers. Yesterday we were treated to nine grad student presentations on topics ranging from the identification of syrphid fly pollinators to the diversity of aquatic invertebrates. Especially, it seemed, there's an awful lot of fly research going on in southern Ontario.

Most interesting to me was a paper given by Joel Gibson of Carleton University on the fly family Conopidae, some members of which are parasitic on bumblebees. Actually the technical term for these Thick-headed Flies is parasitoids. A parasitoid is any parasite that spends an extended time in the body of its host and is so large that as it grows it ultimately kills that host. Parasitoids, you could say, are parasites that are rather more like predators than like ordinary parasites.

Right: A conopid fly of the genus Physocephala, known to be parasitoids of bumblebees. Note that unlike most flies, the antennae are quite long, making it a more effective wasp mimic.

Adult Thick-headed Flies are rather elegant-looking creatures, with a slim, wasp-like body and black-and-yellow waspish colors. They visit flowers where they feed on nectar.

And it is presumably around flowers where they encounter unsuspecting bumblebees. The fly is said to be able to alight on the flying bumblebee and deposit an egg into its body. When the fly larva hatches, it burrows deep into its host and begins to feed on the bumblebee's tissues.

In some areas, we were told, 40% to 50% of the bumblebees are carrying conopid larval parasitoids. The infected bees become feeble and unable to fly. They may be found walking on the ground, their abdomens swollen by the mature fly larva that has consumed most of their internal organs. Eventually the bee dies and the Thick-headed Fly larva pupates inside.

Thick-headed Fly parasitoids are yet another pressure on bumblebee populations. The fly is, no-doubt, something that bumblebees have evolved to cope with over time. But when combined with habitat destruction and widespread pesticide use, this highly effective parasitoid is just one more potentially dangerous stressor.

[Photo by James Lindsey, CC license]

Friday, March 26, 2010

Bumblebees and Climate Change

Bumblebees can now be spotted all year round in southern England (Read more here).

Yes, British Winters are still cold, but not as cold apparently, as they used to be. Bumblebees are hardy anyway, and can continue to fly in search of food at colder temperatures than most other pollinators. Besides, in British gardens there are apparently some cultivated plants that bloom during the Winter months, so the bee food supply is continuous.

Right: The Buff-tailed Bumblebee, a British species seen in very early Spring.

Bumblebees in temperate climates usually escape winter as part of their annual colony life cycle. Normally it is only the fertilized queen that overwinters. In the Fall, she chooses a sheltered spot, often in a shallow burrow in the soil. There she waits until winter has passed and Spring flowers promise a fresh supply of nectar and pollen.

The queen begins a new colony first by finding an abandoned mouse nest or other suitable cavity, often underground. She gathers nectar and pollen to nourish the larvae that develop from the eggs she lays. When her first brood of worker bees emerge as adults, they take over the job of gathering food, leaving the queen to the tasks of laying eggs and maintaining order in the colony.

By mid- to late-Summer, the bumblebee colony starts to produce sexually active males and queens. When these new queens have mated, they are the ones who normally overwinter and begin the next generation. The old queen and the remaining workers and drones usually die when they can no longer find enough food and the first heavy frosts overtake them.

These observations of Winter-active bumblebees in southern England raise some intriguing questions. Are they mated queens that just don't bother to hibernate? Or are they workers and males left over from the previous summer who can still find enough food to survive? If the latter, do last year's workers and males become competitors with the new queens for scarce Spring food resources?

Dave Goulson's observations suggest that mated queens of Bombus terrestris in southern England just go ahead and found a new nest, not bothering to hibernate first. But if they were to start simply laying eggs in their maternal colony, this would seem to put the species well on the way towards continuous, immortal colonies, like those of honey bees.

As with all of the many changes that have occurred in Earth's environment during past millenia, those bumblebees that can adapt gracefully will survive and prosper. Those that cannot adapt will become just another chapter in bumblebee history.

[Photo of B. terrestris from the Wikimedia Commons, CC License]

Wednesday, March 24, 2010

A Hopeful Sign?

The Rusty-patched Bumblebee (RPB) seems to have been a casualty. The Xerces Society, a not-for-profit organization that specializes in the protection of invertebrate animals and their habitat, has identified the Rusty-patched as one of four North American bumblebees that have experienced serious decline in the last 50 years. This RPB is one of the prime examples of why bumblebees need our help.

Right: Color pattern diagrams for workers of the Rusty-patched Bumblebee (Bombus affinis)

The RPB was formerly widely distributed in eastern and central North America. It is represented by specimens in historical insect collections from southern Ontario and Quebec in Canada, and all the way from Minnesota across to Maine in the northern U. S. It also occurred in a wide swath down the eastern part of the continent, as far south as Georgia. Today it has disappeared almost entirely from that entire broad range.

A recent study by bee researchers, Sheila Colla and Laurence Packer has provided quantitative evidence for the decline of the RPB. They collected intensively in two locations where RPB was formerly found over a period of three years. They were completely unable to locate the species in its former haunts. Broader collecting throughout most of the former range turned up only one remaining stand of the species in southern Ontario.

Fortunately, last year, the missing species was also sighted by biologist Liz Day in Indiana. This has to be a hopeful sign.

You can help. The Xerces Society would like everyone to be on the watch for the Rusty-patched Bumblebee. If you want to learn how to spot, they have information and even an identification guide on their site. You can see more photos of the species HERE, HERE and HERE.

There may still be hope for the Rusty-patched Bumblebee. Let's try and give all bumblebees a better chance by protecting their habitat and planting more bee-friendly flowers.

Maybe one day we'll see the RPB flashing its brown patch among the blossoms in our gardens once again.

Sunday, March 21, 2010

Bee Degree Days

In addition to avoiding each other, emerging bumblebee queens need to be out and flying around when their favorite early food plants are blooming. Too early and it's too cool, with no nectar or pollen. Too late, and the blooming period is over, the preferred food all gone.

How do they do it? How do they figure out when to emerge, especially underground, or buried in a rotten log, where the sun doesn't shine to let them know the days are getting longer?

Bumblebees can apparently tell when to emerge the same way biologists can predict the dates for Spring plants to flower - they use growing degree days.

Biologists have found that Spring flowers bloom after their buds have received enough heat. During the depths of winter, no bud development happens at all. But in late Winter and early Spring, the days start to get warmer. Every day the temperature is above approximately 50 degrees F, the flower bud grows and develops a bit more. Finally, when there have been enough hours warm enough for growth, development is complete and the blossom unfolds.

We know it's accumulated warming that makes the difference, because if it was just the increasing daylength, Spring flowers would bloom on the same date each year. They don't. They bloom earlier in a warm Spring and later in a cool one.

It turns out you can calculate the amount of heat a Spring flowering plant is receiving using a measure called degree days. You add up all the hours since January 1st that the air temperature has been above 50 degrees F and divide by 24 to get a measure called a growing degree day. But since we're interested in bumblebees, we'll call them bee degree days. You can read more about degree days and how to calculate them HERE and HERE.

So if we, or the bumblebee, can keep track of the number of bee degree days, we can predict when the flowers will appear. Each species of flowering plant seems to have its own, unique required number of degree days for blossoming.

Hibernating bumblebees, of course, do not use computers and trig functions to calculate bee degree days. In all likelihood, some aspect of their internal body chemistry changes slowly when the temperature is warm enough. After enough warm days, the chemistry has changed enough to wake up the slumbering queen.

Soon she's on her way, in search of that first, quick pick-me-up of fresh Spring nectar.

[Photo by Tony Wills, CC License]

Friday, March 19, 2010

Bumblebee Mating

Not exactly seasonal, but I wanted to show you this photo, sent to me by a friend, of Common Eastern Bumblebees (Bombus impatiens) mating last Fall.

The queen is the larger individual, clinging to the edge of a leaf, and the considerably smaller male is hanging below her.

By mid- to late summer, new virgin queen and male bumblebees are produced from successful colonies. These individuals leave the nest and seek each other out for purposes of reproduction.

Mate seeking in bumblebees was first recorded by Charles Darwin who set his children the task of following male bumblebees in his garden to record their behavior. The males of most species patrol a route which they mark with scent produced by their labial glands. The pheromone is deposited on "leaves, prominent stones, fence posts or tree trunks" according to Dave Goulson in his book, 'Bumblebees: Behaviour, Biology and Conservation'. It's not certain exactly how the newly emerged queen encounters the patrolling male. Presumably a combination of the species specific pheromone used for marking and the height above ground of the male's patrolling route provides the appropriate cue.

Observations are few, but presumably the male and female make contact in the air. Then, shortly after coupling, they alight until copulation is complete.

[Photo by Michelle Arsenault]

Monday, March 15, 2010

Queens Spring Into Action

Spring is the time for hope and for creating new life. But Spring can be the most dangerous period of the year for bumblebees.

We'll be seeing bumblebees on the wing soon (our colleagues in England are seeing them already), for Spring is when mated queens emerge from hibernation. Each has overwintered in a shallow burrow in the soil. Energized by the warming rays of the sun, each queen must crawl to the surface and fly off in search of a first meal of nectar to fuel the colony founding tasks that lie ahead.

But what if an unusually cold winter or Spring rains that flood the soil kill off most of the hibernators? What if there are no blossoms to forage after they emerge? What if too many queens have survived and there is not enough nectar to go around?

An uncertain environment and intense competition make each new Spring a challenge. This is why early bumblebee populations may be boom or bust - tens of thousands of queens in some years, few in others.

One strategy that bumblebees appear to have evolved in order to reduce competition for resources each Spring is staggering emergence times. North American bumblebees (like those in any temperate climate) can be characterized as either early-Spring, mid-Spring or late-Spring emergers.

Right: Emergence pattern for 3 common eastern North American bumblebee queens.

Because most wildflowers bloom at different times through the season, early emerging queens have access to a different initial food supply than those emerging later on. The result - more bumblebee species can co-exist in the same community than if they competed head on for every resource.

Friday, March 12, 2010

"Nectar gone. Don't bother"

How do bees, either bumblebees or honey bees, collect nectar and pollen as efficiently as possible? This activity is called foraging, and it is central to the success of any social bee colony.
Honey bee and bumblebee, both foraging on goldenrod

Foraging has been studied best in honey bees, and they are known to use a variety of techniques including aromas, communicating flower location, and scent marking to ensure that individual workers do not waste a lot of time looking for food in unlikely places.

Bumblebees also use scent marking to improve their foraging efficiency. Apparently it works like this. Each bumblebee body is coated with a number of chemicals that serve to waterproof its exoskeleton. As a bee walks over the surface of a flower collecting nectar and pollen its feet leave traces of these chemicals behind.

The next bee to come along can detect the presence of the chemical marker left by the previous forager using sensory organs in its antennae. Bumblebees can often be seen hovering just in front a flower before deciding to alight or instead to move on to the next blossom. It seems that if the bee finds that another has just been working on the flower, it moves on, knowing that the nectar in that flower has probably been used up.

So bumblebees warn each other off a flower that has little nectar left. And honey bees do the same thing. The chemical markers used by different species are fairly similar, and it seems that bumblebees can recognize the 'no nectar' signal left by honey bees.

This chemical marking behavior is probably why you never seem to see bees fighting over a flower. It's a way to ensure that all of them make the best use of their time in the field.

But it also suggests that if you have a lot of foraging honey bees out there marking flowers with 'no nectar' signs, there may not be much left over for the less abundant bumblebees.

[Honey bee and bumblebee photos by D. Barr]

Wednesday, March 10, 2010

New Bumblebee Sightings in Scotland

Things may be looking up for bumblebees in Scotland. One rare and endangered species for that country, the Great Yellow Bumblebee, was seen farther south last summer than at any time in the past 30 years. This species has been declining for some time in the UK, and populations have been restricted to the far northern highlands and isolated northern islands of Scotland.

A possibly less auspicious sighting came early this year. The Southern Cuckoo Bumblebee (SCB) was spotted near the southern border of Scotland, a new species for the country. Previously the SCB has been common in the UK only near the southern coast of England.

Yes, it's a new bumblebee for Scotland, and a species that seems to be expanding its range rather than being in decline. But is this a good thing for bumblebees as a whole?

The questions arises because cuckoo bumblebees are parasites in the nest of other bumblebees. The normal bumblebee colony lives and grows by harvesting nectar and pollen from flowering plants. Most bumblebees have a number of special adaptations for pollen gathering, the most obvious of which is the presence of a wide, pollen gathering 'basket' on both hind legs.

Cuckoo bumblebees, on the other hand, have no pollen basket and make their living by invading the nests of pollen gathering species. The 'cuckoo' female takes over from the queen of the host species and begins to lay eggs. The workers of the host bumblebee then proceed to rear the cuckoo's eggs as though they were their own sisters. As a result the host colony rears no queens to carry on the next generation. All queens and males produced from that time on belong to the cuckoo species.

So you can see that a new cuckoo bumblebee is a mixed blessing. It can prosper only at the expense of normal bumblebee populations.

The ability to keep track of the gradual changes in UK bumblebee populations is possible largely because of the efforts of organizations like the Bumblebee Conservation Trust. Without a concerted effort to monitor pollinator populations, we are in danger of losing these critical components of our ecosystems before anyone has the chance to take action to save them.

Let's watch those bumblebees.

[The photo above is of the Great Yellow Bumblebee (Bombus distinguendus), taken by James Lindsay and made available under a Creative Commons licence.]

Sunday, March 7, 2010

Which Bumblebee Is That?

This is one of a series of short notes on recognizing commonly seen bumblebees.

Just noticed the great bumblebee illustration on the cover of the book, 'Peterson First Guide to Insects of North America.'

According to Paul Williams' online key, this looks like it ought to be Bombus pensylvanicus, the American Bumblebee. This species can usually be recognized by the single yellow band at the front of the thorax, together with broad yellow bands on the 2nd and 3rd abdominal segments. The individual illustrated has the first abdominal segment all yellow, while many females (queens and workers) of this species have only a narrow yellow band at the back of this segment.

For many of us it seems easier to become familiar with insects that have a common name, like the American Bumblebee, in addition to its latin name (Bombus pensylvanicus). Many North American bumblebees don't seem to have been given common names yet. But here are about 20 exceptions:

Common Eastern Bumblebee - Bombus impatiens
Black and Gold Bumblebee - Bombus auricomus
Rusty Patch(ed) Bumblebee - Bombus affinis
Yellow Banded Bumblebee - Bombus terricola
Southern Plains Bumblebee - Bombus fraternus
Brownbelted Bumblebee - Bombus griseocollis
Redbelted Bumblebee - Bombus rufocinctus
Lemon Cuckoo Bumblebee - Bombus citrinus
Fernald Cuckoo Bumblebee - Bombus fernaldae
Indiscriminate Cuckoo Bumblebee - Bombus insularis
Ashton Cuckoo Bumblebee - Bombus ashtoni
Two-spotted Bumblebee - Bombus bimaculatus
Confusing Bumblebee - Bombus perplexus
Tricolored Bumblebee - Bombus ternarius
Half-black Bumblebee - Bombus vagans
Yellow-faced Bumblebee - Bombus vosnesenskii
Northern Amber Bumblebee - Bombus borealis
Yellow Bumblebee - Bombus fervidus
American Bumblebee - Bombus pensylvanicus
Franklin's Bumblebee - Bombus franklini
Western Bumblebee - Bombus occidentalis
Sanderson Bumblebee - Bombus sandersoni
Variable Cuckoo Bumblebee - Bombus variabilis

You can buy this beginner's insect field guide, with the cover illustration shown above, at

Tuesday, March 2, 2010

Some Other Native Pollinators

Bumblebees are special and unique in many ways. One way in which they are not unique is in being a group of native pollinators. There are also lots of other native insect pollinators, hundreds of different species.

Many of our native pollinators are bees as well, but there are also lots of flies, wasps, butterflies, moths, and beetles that provide pollination services to flowering plants.

Debbie Hadley, who writes about insects for, has provided a nice overview of 10 important native pollinators, all of which happen to be bees. And this is appropriate because of all the insects, bees are the most thoroughly adapted for gathering pollen and transfering it from flower to flower.

To put Debbie's 10 pollinators in context, approximately 17,000 species are from known around the world at present. And those species can be divided into about 7 families. A family is a group of species that have a lot of things in common, things like anatomy, behaviour and ecology. And most bee families differ from each other in appearance, habits and lifestyle.

All this is only to point out that although the bumblebee ways of pollinating plants are very effective, they are by no means the only methods of doing so.

Find out what Debbie Hadley has to say about the ways carpenter bees, mason bees, sweat bees, polyester bees, squash bees, dwarf carpenter bees, leafcutter bees, alkali bees and digger bees. You'll be amazed at how many of these little creatures are helping us out by pollinating our fruit and vegetable crops.

I'm glad bumblebees are the first on Debbie's list. Fortunately, many of the things we can do to support bumblebees, things like planting bee-friendly gardens, will support the rest of the native bees as well. Debbie has also posted a list of 12 things you can do to help native bees.

Bees just love flowers, so we have to give them all we can.

[The photograph is of a mason bee, courtesy of USDA, made available on the Wikimedia Commons and in the public domain.]

Sunday, February 28, 2010

Bumblebee Declines in the United Kingdom

Bumblebees the world over are threatened. Nowhere perhaps, is this better documented than in the United Kingdom. The level of scientific, public and amateur interest in bumblebees there is among the highest in the world. So the British have good records on their bumblebee populations, some of them dating back over a hundred years, The UK even has a not-for-profit organization dedicated to preserving native populations, The Bumblebee Conservation Trust.

And here's the sad truth that has been discovered. Although the UK currently has a relatively diverse bumblebee fauna, with 24 species, only six of these remain relatively common while over the last 70 years the rest have declined to varying degrees. During that period, two species have become extinct in the region. The survival of a further six species is so endangered they have been designated priority species under the terms of the UK Biodiversity Action Plan.

Local bumblebee supporters are highly active in trying to preserve species that, like the Shrill Carder and Great Yellow Bumblebees, have become rare and exist only in a few isolated populations. And they have discovered, with great delight, that one of the species now extinct in the UK, the Short Haired Bumblebee, still survives in New Zealand, because it was introduced there in the late 19th century in order to pollinate clover crops. Now a conservation group called Natural England is undertaking to transplant individuals of the lost species back into the UK in order to re-establish the former populations.

Other events are on the move as well. A European species called the Tree Bumblebee that was never present in Britain before has now invaded the country from the south coast and is heading northward.

Things are changing fast for crop pollinating bumblebees in the UK and only a vigilant monitoring program will provide enough information to know which bees to try and help, and when.

[The photo is of the Tree Bumblebee, by Rasbak, Creative Commons and GNU licences]

Friday, February 26, 2010

Bumblebee Colors

Colors? What colors? Bumblebees are black and yellow, right?

Well yes, many of them are. But lots of bumblebees have brown, red, and white colors as well.

And even when black and yellow, most bumblebees do not fit our popular, oversimplified image of alternating black and yellow bands around the body.

In fact the patches of color that decorate the bumblebee's generally black body can appear in a vast variety of patterns of varying complexity.

Central to this issue of bumblebee color patterns is the fact that there are many different kinds, or distinct species, of bumblebees. Who knew? When I was a kid, even though I was wise to the different species of butterflies that I saw visiting flowers, I thought all bumblebees were the same. And I'm sure this is true for most people. Scientists, however, have discovered about 250 species worldwide and around 50 in North America alone. The first clue to understanding this tremendous bumblebee diversity is noticing the variety of color patterns they display.

Students of the bumblebee have discovered that most individual species can be identified primarily on the basis of the color pattern. That means that the color patterns of different species are different from each other most of the time. There are a number of factors that tend to confuse the issue, but we'll get to that in a moment. For now, all we need to recognize is that most books, websites and identification guides to bumblebees use color patterns as the most important means of distinguishing one species from another.

Here's how the observation of color patterns works. First we start out with a silhouette of the upper surface of the bumblebee body in diagrammatic form. The silhouette is all black, as that is the basic color of the exoskeleton in these insects. The main body parts shown are the head, thorax and abdomen. The individual segments of the abodomen, six in queens and workers, are numbered from front to back as T1 through T6. In this numbering system, the 'T' stands for 'tergite,' the anatomical term given to the exoskeletal plate that forms the upper surface of each abdominal segment.

Then, on top of the basic silhouette are added a number of colored areas... various shades of yellow, red, brown and white. These colored areas correspond to dense patches of hairs, referred to as pile, occurring on the body. The shape, color and location of these patches is what determines the overall color pattern.
Using this system to take a quick look at some of the color patterns of different bumblebee species not only provides a useful starting point for identification, it is a breathtaking reminder of the diversity of ecologies and lifestyles these pollinators have evolved.

Postscript: The simple correspondence between a single color pattern and a single bumblebee species is complicated by three facts of life in the bumblebee world - polymorphism, Mullerian mimicry and cryptic species. More about these issues in later posts to this blog. [Images copyright (c) Dave Barr, 2010]

Friday, February 19, 2010

Bumblebees on The Web

Not a spider's web, of course. Most bumblebee queens and large workers are strong and heavy enough to extricate themselves from a spider's web. Although the smaller workers could easily be trapped, one seldom sees them suspended from an orb web. Perhaps their defensive sting convinces the spider to cut them out, or perhaps they are just good at sensing and avoiding the spider webs in the first place.

Today's posting is actually about bumblebees on the World Wide Web. Fortunately there is loads of good information out there, and all freely available too.

The place where every bumblebee afficionado should start is ( This site aims to be the textbook of bumblebee biology, providing detailed information that is well illustrated. Here you can find out about bumblebee anatomy, nests, life cycles, feeding, foraging, behavior, economic importance and much, much more. The focus is on British species, but most of the biological information applies to species found in the rest of the world as well. The color patterns of North American bumblebees are illustrated, so you can make a start at recognizing species on both sides of the Atlantic. That's one of the great photos from on the right.

If, on the other hand, you just want a quick overview, try the Wikipedia page:

Learn about some of the conservation issues for bumblebees, especially in Britain, at the Bumblebee Conservation Trust [], and for North America at the Xerces Society [].

Information on Bumblebees of The World is featured at the Natural History Museum (London) []. And you can see some great, hi-res photos at:

Thursday, February 18, 2010

How Can A Bumblebee Fly? - New Insights

Almost everyone has heard the story (probably meant to discredit science) of how scientists have calculated that the bumblebee cannot fly. All bumblebees, as everyone knows, can actually fly quite well.

Explanations of the origin of this humorous story vary, but it may be based on the principles of flight that apply to the earliest fixed-wing aircraft. In those early planes the weight that could be lifted was roughly proportional to the surface area of the wings. Now bumblebees, when compared to butterflies or locusts have rather small wings in proportion to the size of their bodies. Obviously, any comparison to a fixed wing aircraft is misleading.

Instead, bumblebee wings, as it turns out, seem to have more in common with helicopter blades than with airplane wings. Watch this short YouTube slow motion video to see the bee using its wings to fly up, down, sideways and even backwards as it navigates around a flower blossom - The wings beat, or oscillate at high frequency and those oscillations create a vortex (like a mini-tornado) in the air above the wing. The vortex produces considerably more lift than a fixed wing, thus allowing the bumblebee to escape the limitations of the Wright brothers' craft.

Like all bees, bumblebees have two wings on each side of the body. But the two wings on the same side are coupled together with a row of microscopic hooks so that they move as one. Using a wind tunnel and smoke streams, biologists at Oxford University have recently demonstrated that in flight the wings on one side operate independently of those on the other side - This means that the bee beats its way through the air, rather than gliding forward with a smoothly coordinated rowing or gliding motion.

The flight of the bumblebee may be inefficient, but it probably makes the insect much more manoeuverable, allowing it to turn quickly from one blossom to the next, and weave its way among flowers dangling close to each other. And they seldom fly far. Most foraging flights are less than 500 metres from the nest.

Wednesday, February 17, 2010

Saving Native Pollinators

This afternoon I attended a webinar given by Ted Leischner who has been a commercial beekeeper and is now actively involved in monitoring and communicating about native pollinator species. To the right you can see one of his slides (used by permission) highlighting the importance of bumblebees.

The webinar, entitled "What Happens When the Honey Bees Disappear," was organized by the Certified Organic Associations of British Columbia (

About 75% of the 240,000 species of flowering plants on earth need pollen transfer services from animals to ensure their survival. The equation is a simple one: no pollinators = no fruits and vegetables for we humans. As animal pollinators disappear, so will the plant species that depend on their pollination services.

In agriculture we have come to depend increasingly on commercially managed honey bees to pollinate major crops like almonds, apples, blueberries, canola and peaches. But as Leischner pointed out, honey bees are in trouble. Due to Colony Collapse Disorder and the inroads of Varroa mites and other parasites and pathogens, over 30% of honey bee colonies are being lost each year. So "what happens," Leischner asks, "when the honey bees disappear?"

His answer is simple and direct. We have to be prepared to depend more on native pollinating insects, mostly various species of bees, for help in sustaining earth's ecology and the security of our own food supply. Unfortunately, native pollinators are under pressure and experiencing decline themselves. The 2007, multidisciplinary report on the Status of Pollinators in North America ( concluded that many pollinators are in decline and discussed the causes and consequences. The biggest culprits seem to be industrialized, monocultural agriculture and the loss of habitat and food resources everywhere.

Leischner wants us to start now by learning more about native pollinators and their needs. Then we can begin to reverse their decline by providing the habitat and flowering plant resources native pollinators need to survive. Helping them is not only helping the ecosystem, it is helping ourselves as well.

In all of this, bumblebees play a key role. Some species are clearly endangered, threatened with extinction, both in North America and Europe. Bumblebees are major players in the production of human food. They participate in the pollination of some 50 species of crop plants ( Along with the rest of the native pollinators, we need the bumblebee.

You can get in touch with Ted Leischner at or 250-499-9471.

Tuesday, February 16, 2010

Meet The Bumblebees

Bumblebees are one of the most familiar insects visiting our gardens and parks. Just about anywhere you find flowers growing in temperate regions of the world, you will find bumblebees. These big, fuzzy, black-and-yellow bees buzz from flower to flower, lapping up nectar with their tongues and collecting the pollen that adheres to the dense layer of hairs covering most parts of their bodies. Almost all of us can recognize a bumblebee on sight.

Bumblebees are pollinators, a critical link in the reproduction of huge numbers of flowering plants, including many of those that supply the fruits and vegetables in the human diet. So bumblebees are part of the web of natural organisms that sustain all life on earth.

But bumblebees are in trouble. Their numbers are changing rapidly and they need our help.

In this blog we will be exploring the world of bumblebees and trying to discover what we have to do to ensure that these native pollinators will continue to fulfill their critical role in the ecosystem we all share.

[Image copyright (c) Dave Barr 2010]


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