This program premiered October 28, 2007.

NATURE goes behind the scenes of Silence of the Bees with an interview with producer Doug Shultz.

What is the story you tell in Silence of the Bees?

The film actually encompasses three parallel stories. The first is the overall mystery of why the bees are disappearing, and the scientific investigations that are under way to try to understand this. The second is the surprising reliance that we have on this completely unnatural system of trucking bees around the country to pollinate our crops. This is something that I think has taken everyone by surprise. Third, maybe most fascinating of all, is the story of the honeybee itself. To understand the magnitude of the problem and what we’re losing, it’s important to appreciate how extraordinary these animals are, and the value of what they contribute to the planet. And to our plates!

Theories about the cause of CCD changed and expanded while you were in production and they continue to evolve now. How did that create challenges in the filmmaking process?

From the beginning we knew we were along for an uncertain ride — would we have an answer by the time production wrapped? But it was such a great detective story that we just stayed on top of the latest developments and maintained contact with all the key players to find out which theories they had crossed off the list and which they were still exploring. The biggest challenge, actually, was the research embargo. We knew our scientists had found something, but they couldn’t tell us what it was until the research was published. We were nearly finished with our edit by the time they were allowed to talk. So much of the time we were planning shoots based on our own hypotheses of what was going on.

Filmmaker Doug Shultz

Bee population decline has been recorded all over the world. How did you select the locations where you shot and the stories that you told in the program?

It’s true that bee populations are declining nearly everywhere, and not just from CCD. So we tried to target locations that served a purpose in the overall story. France stood in as a case study for pesticide use and its effects on bees. They have had some very intense clashes over this issue, and in fact have banned chemicals that we now use in the United States. We went to Spain because they have the highest number of commercial beekeepers in Europe, and last year they suffered massive bee losses. England was an example of controversy, where beekeepers claim they’ve lost up to two thirds of their bees, but the government still insists they don’t have a problem. We also went to China because in the south, there’s a region that sort of stands as a grim omen of what a world without bees could be like.

What are some of the practical and technical challenges of filming bees versus getting footage of larger animals?

Well, they sting. But the main thing is that they are very small and very fast. So because you’re focused on such a small area, you don’t have much latitude to move with them. It requires a great deal of patience. You set up your shot over a flower, for example, and you hope that eventually a bee will stop by and will stay within your focal range for a reasonable amount of time. When you’re shooting inside the hive, you really can only shoot for a short amount of time, because once the bees are stirred up, there’s really no calming them down. Bees also flap their wings at a speed faster than the known laws of physics can explain. We used the new Phantom HD high-speed camera to capture this at up to 1,500 frames per second.

What went into getting shots inside the hive?

The hive is really like one big organism, and we poked and prodded into it with a variety of borescopes and macroscopic lenses. The real challenge is that many of the most interesting behaviors happen on such a small scale that they can be incredibly difficult to capture. Olympus America generously brought out a new HD endoscopic camera normally used for examining the inside of a human esophagus — they wheeled it right out into a pumpkin patch in Pennsylvania for us and we stuck it in a hive. We also had the help of several very knowledgeable and patient beekeepers who were able to quickly find certain behaviors in the hives.

When shooting the hive scenes, your on-camera experts are all in protective gear and masks. Did the crew wear something too? Did people get stung?

We all wore bee suits, and learned very quickly to make sure we were completely zipped up. On our first shoot in Maine, it was pretty chilly, and the bees were looking for some warmth…inside our suits. We all got stung. The bees even attacked the windjammer on the mic because they thought it was a bear. Spanish bees are particularly aggressive, and in Andalucia we were wearing extremely thick, double-layered bee suits in 110-degree weather. No one got stung, but I think we all lost weight.

Once we became accustomed to being around the bees, we let our guard down a bit. I got stung again a few times in France and ended up with a temporarily deformed head. But we all still love bees.

For this production, did you put yourself through some kind of “Bee Boot Camp” to become familiar with the natural history of bees?

I started by reading as much as I could about honeybees and beekeeping in general, and there was much more to learn than I had anticipated. Bees and bee societies are incredibly complex. In the case of this film, all that information was just base knowledge, because the film was an investigation into CCD, not just the natural history of the bee. The real boot camp came on our first shoot with commercial beekeepers, actually seeing how the whole business works.

David Hackenberg unloading his beehives in Maine for blueberry pollination.

Do you have a favorite sequence in the film?

That’s tough, but I really like the scenes in Maine, where they’re distributing the hives in the blueberry fields, dealing with bear damage, etc. Every time people see this, they are blown away because very few people know this goes on. I also like the China sequence because what’s happening there is pretty hard to believe as well.

Did something end up on the “cutting room floor” that you wish made it into the film?

I wish we had more time in the film to spend with all the different beekeepers. They’re a special breed of people and their enthusiasm for the bees is infectious — by the end, we were all considering starting hives, ourselves. Unfortunately, because of the amount of information we had to wrangle into an hour-long film, many of these characters had to be cut for time.

What appealed to you about working for NATURE?

Well, I’ve always been a fan of NATURE, and as far as natural history programming goes, they are the best. This is something a little different for NATURE because it incorporates natural history into a more investigative, topical story. It was an appealing challenge to find a way to make that work, both thematically and stylistically.

Is there anything else you would like to add?

I think it’s important to note that the CCD scare has brought some overdue attention to the importance of bees, but bees and other pollinating animals have been disappearing for at least 20 or 30 years. This is just the latest example of a worldwide crisis that until now really hasn’t received the kind of attention that something like global warming gets. But pollinator decline is just as important — and just as worrisome.

To watch an interview with Doug on the The Alcove with Mark Molaro, click here.

Go Retro — Become a Backyard Beekeeper

Over the years, our diets have increased the demand for a constant stream of all-season fruits and veggies. Such demand hasn’t bypassed the bees. It’s turned bee pollination into a year-round service and beekeeping into a commercial industry. Today, there are half as many beekeepers as there were two decades ago, and the remaining beekeepers are mostly large-scale pollination services with thousands of hives and millions of bees. But there was a time when beekeeping was much more of a hobby than a commercial industry. “Beekeeping is a graying hobby,” says Jeff Pettis of the Dept of Agriculture. Joining the ranks of backyard beekeepers can not only infuse the dying hobby with life, it can strengthen the bee gene pool by adding healthy local bees to the mix.

If you’re interested in becoming a backyard beekeeper, experts recommend starting with a local beekeepers’ association to learn about keeping bees alive and healthy. It’s important that bees are adapted to the local climate, so you’ll want to start with a local source for bees. Aside from contributing to the bee population, just two hives can pollinate an entire mid-sized residential garden. You might just find yourself with a lifelong hobby. For most people, beekeeping grows into a passion.

Get Closer to Nature

Backyard gardens can offer a welcome supply of nectar and pollen for honeybees.

If you decide to pass putting on a beekeeper’s suit, merely keeping a backyard bee garden is another good deed you can do for the honeybees. With rapid urban development limiting their foraging habitat, backyard gardens can offer a welcome supply of nectar and pollen for honeybees.

Cultivating plants that will attract bees is the most important task of a bee gardener. Choose flowers that bloom successively over the spring, summer, and fall seasons such as coreopsis, Russian sage, or germander in order to provide pollen and nectar resources to the native bees of all seasons. If you’re not sure what to choose, you can always check with a local garden center for their advice on “bee-friendly” florals. To improve bee visitation, the garden should contain large patches of like flowers planted in close proximity to one another. Diversity is a key factor in keeping bee gardens buzzing. Researchers have found that more bees will be drawn to gardens with ten or more species of attractive plants.

As you diversify your garden, keep part of it wild because bees prefer that to a manicured space. Go for a “planted by nature” effect rather than a perfectly pruned garden. Remember: bees don’t discriminate between weeds and cultivated flowers, so let those dandelions grow.

And of course keep your bee garden free of pesticides — a danger in any garden. Some pesticides can kill the bee before it returns to the hive; other pesticides get carried back and can harm the rest of the hive.

If, after all of your hard work, you’re still not seeing bees in your garden, it’s not a wasted effort. Growing a pesticide-free garden is also good for you if you’re growing fruits and vegetables. Robert Mendela, President of the Backyard Beekeepers Association, says, “Even if there isn’t a hive of honeybees within a couple of miles of your garden, gardening brings the grower closer to nature and closer to realizing that what s/he grows is more nutritious and tasty than the ‘factory-ized,’ perfect, unblemished, and perhaps pesticide-covered” produce.

Even if you don’t have a green thumb, buying pesticide-free foods at the market also protects humans and bees from pesticide poisons.

Give the Bees a Voice

“Something the average person can do,” says Mendela, “is to write to their senators and representatives in congress on the federal level and to do the same on the state level to support funding of honeybee research. This support has fallen off over the years.”

The news focus on CCD makes it an ideal time to put pressure on politicians to reinstate laws that used to prevent importing bees into the country and transporting them across state borders.

Large or small, any effort you make to help bees or increase awareness is a step towards healthy bees, healthy crops, and, consequently, healthy humans.

The role honeybees play in our diet goes beyond honey production. These seemingly tireless creatures pollinate about one-third of crop species in the U.S. Honeybees pollinate about 100 flowering food crops including apples, nuts, broccoli, avocados, soybeans, asparagus, celery, squash and cucumbers, citrus fruit, peaches, kiwi, cherries, blueberries, cranberries, strawberries, cantaloupe, melons, as well as animal-feed crops, such as the clover that’s fed to dairy cows. Essentially all flowering plants need bees to survive.

A daunting question is: If honeybee colonies were so severely affected by CCD that pollination stopped, could we lose these crops from our markets and our diets forever?

Honeybees pollinate about 100 flowering crops.

“We’re not there yet,” says Jeff Pettis of the USDA. Pettis says there are steps researchers and beekeepers can take to ensure that the bee population doesn’t plummet to catastrophic levels. “One measure beekeepers have been taking is to keep bees as healthy as possible — improve nutrition and reduce stress,” says Pettis. Consumers have become more demanding and expect to have fruits and vegetables available to us all year round. In order to achieve this, commercial beekeepers haul colonies of honeybees across the country so their pollination services can serve all growing seasons. The season may start with almonds in California, then move on to apples in the Northwest, cranberries in New Jersey and Maine blueberries. The constant moving about places stress on the bees. In addition, certain crops that may be in the pollination circuit, like cranberries and cucumbers, are not very nutritious for bees. To keep the bees healthy, beekeepers may need to ease up on their schedules. It may be necessary for them to retire bees for a particular season or skip some less nutritious crops entirely.

Of course, nature has its own safeguards to keep crops pollinated. Honeybees aren’t our only pollinators. Other insects and birds pollinate fruits and vegetables as well. The problem with other natural pollinators picking up the bees’ slack is that today’s agricultural industry has simply grown too large for them to keep up. The leviathan that is U.S. agriculture creates a huge demand for pollination. Because honeybees are relatively mobile and can pollinate a generous number of crops, they have been the ideal recruits to meet our crop needs. But honeybees don’t perform such feats naturally without help — lots of it. Commercial beekeepers keep colonies nourished and healthy and move their hives from state to state in semis, selling their pollination services to farmers at a premium.

With the threat of CCD looming, researchers are starting to study how other pollinators like the larger bumble bees could step in for honeybees. “The Dutch have figured out how to use bumblebees,” says Pettis. Bumblebees share many similarities with honeybees. Both are social nesters, although the bumblebees’ society is not as highly ordered as that of honeybees. Also, bumblebees make a new nest each spring by solitary queens, who hibernate through the winter. Honeybees remain in the old nest.

Perhaps the biggest consideration is an economic one. Bumblebees last just 2 months and cost $200 per colony, whereas honeybees can last several months in the summer with colony rentals running only $100 to $140. As a result, the use of bumblebee pollination is usually confined to high-value crops like tomatoes. Clearly, the use of bumblebees is a step in the right direction, but not a final solution.

“There’s nothing waiting in the wings that can replace honeybees at this time,” says Pettis, “but we can solve the problem in honeybee health.” Pettis says that by focusing on reducing stress and improving nutrition, beekeepers can limit some of the factors that potentially lead to disastrous conditions like CCD, thereby keeping bees — and our diets — healthy.

Silence of the Bees is the first in-depth look at the search to uncover what is killing the honeybee. The filmmakers of Bees take viewers around the world to the sites of fallen hives, to high-tech labs, where scientists race to uncover clues, and even deep inside honeybee colonies. Silence of the Bees is the story of a riveting, ongoing investigation to save honeybees from dying out. The film goes beyond the unsolved mystery to tell the story of the honeybee itself, its invaluable impact on our diets and takes a look at what’s at stake if honeybees disappear. Silence of the Bees explores the complex world of the honeybee in crisis and instills in viewers a sense of urgency to learn ways to help these extraordinary animals.

Silence of the Bees premiered on PBS October 28, 2007.

Exclusive Podcast: In this podcast, scientists and bee experts featured in the program discuss the crucial role that honeybees, a “keystone species,” play in our economy and ecosystems, as well as bees’ fascinating social organization and what we can do to reverse the decline of nature’s pollinators.

In May 2009, NATURE Online asked Dennis van Engelsdorp, Pennsylvania’s acting state beekeeper, to comment on recent developments in the investigation into Colony Collapse Disorder. Here’s what he had to say. Check back later in May for a new report detailing colony losses in the U.S. for this past winter.

Q: A new study by Spanish researchers, published in the February ’09 edition of the Environmental Microbiology Reports journal, suggests that the fungus Nosema ceranae had been isolated as the cause of colony collapse in two affected beekeeper colonies in Spain. Is this fungus responsible for the Colony Collapse Disorder in the U.S.?

A: Absolutely not. We identified Nosema ceranae right from the beginning, and right away it was clear that Nosema ceranae could not, on its own, explain losses CCD losses in America. I don’t know about Spain, but there are [scientists and beekeepers] in Europe who have had high losses who are saying it’s not Nosema ceranae. What we do know is that the description of mortality described in these papers isn’t the same as Colony Collapse Disorder.   I think what’s happening is that CCD has caught people’s attention and so now everything that is a colony dying is “Colony Collapse Disorder.” And that’s not true. Colony Collapse Disorder is a very defined set of traits: a rapid loss of the adult population and no dead bees in the bee yard or in the bee colonies, and that’s certainly not what this research described.  We also know that in America, not all colonies have Nosema ceranae — colonies have a lot of viruses. So instead of having one or two viruses, they’ll have five or six viruses. We think they have something like the flu, and this flu is simply wiping through. The question is “Why suddenly are the bees so susceptible to all of these other pathogens — including Nosema ceranae but certainly not limited to Nosema ceranae.

What kind of reception is the study having with experts in Spain and Europe right now?

I work with the American group and we were at the first conference they put together to try to figure out [the causes of] Colony Collapse Disorder. We said, “well, we don’t think it’s this because half the colonies that have CCD don’t have any Nosema ceranae.” It just seems like it’s a distraction, and it’s unfortunate because surely there are people in Spain, and in America, who have a problem with Nosema ceranae, and it’s very treatable. And our recommendation is to treat for Nosema ceranae because it is another stress, and if you reduce stress you’re probably going to help your bees out. But this “Oh we found the solution” sort of dilutes the pressure that exists to make sure we have the funding and resources we need to solve this problem. And we really do need to solve this problem.

Are there any other recent developments regarding CCD in North America since we last spoke in June 2008?

We have discovered a condition we’re calling entombed pollen, where there are high levels of fungicide in some pollen that might be associated with mortality. Certainly most of the colonies that are dying are not dying from CCD. Most of them are dying from poor queen quality, which is something that’s surprising.

Could you explain what you mean by “poor queen quality”?

Every colony has a queen, and what we’re finding is that those queens are dying. And if a colony is unable to successfully replace them, or if the beekeeper is unable to identify that there’s a problem with the queen and buy a new queen to replace her, the colony dies.

Also, we’re finding that beekeepers tend to have better success keeping their colonies alive by keeping colonies as healthy as possible and by aggressively treating disease and keeping colonies well nourished.

An updated development happening in California relates to almonds. You may remember from your Silence of the Bees film that normally half the colonies in the country are needed to pollinate the almond crop.  Demand for almonds was expected to grow through 2012, and there was an expectation that there wouldn’t be enough bee colonies in the country to pollinate the almonds. With the drought in California, it appears that they are now plowing under some of the older almond orchards. That has taken some of the pressure off, and we aren’t seeing some of the pollinator shortages we expected.

In June 2008, NATURE checked in with Pennsylvania’s acting state beekeeper, Dennis van Engelsdorp, for an update on the latest details on the investigation into Colony Collapse Disorder.

Q: In Silence of the Bees, you are shown monitoring a quarantine of several collapsing hives from a Pennsylvania beekeeper. Is this monitoring ongoing?

A: All of the original colonies died by December [2007]. We now have eight new colonies at that site, and continue to sample once a week. We are watching disease growth curves, and this year we are sampling a more diverse range of bees.

What have you been hearing recently from other beekeepers?

The Apiary Inspectors of America (AIA) commissioned a survey to estimate colony losses across the country between September 2007 and 2008. The USDA-ARS Beltsville Honey Bee Lab conducted a similar survey of beekeepers pollinating almonds in California in February 2008. In total, nearly 19 percent of the country’s estimated 2.44 million colonies were surveyed. A total loss of 36 percent of managed honey bee colonies was recorded. This represents a 13.5 percent increase in total losses as compared to last year. The 327 operators surveyed lost nearly a third of their colonies, on average.

Are all of these losses attributable to CCD?

One of the symptoms of Colony Collapse Disorder is the complete absence of bees in dead colonies. The AIA survey data doesn’t differentiate between true CCD cases and other cases that share this symptom. However, the 37.5 percent of operations that reported having at least some of their colonies die with this symptom had a total colony loss of about 41 percent. This compares to the roughly 17 percent colony loss reported by beekeepers who didn’t have “the complete absence of bees.”

It’s important to keep in mind that at least 71 percent of all colony deaths can be attributed non-CCD causes. This really emphasizes the need for further research into pollinator health in general — not just CCD.

Last October NATURE Online reported the research breakthrough that Israeli Acute Paralysis Virus (IAPV) had been found in over 96 percent of bees from CCD-affected hives. This doesn’t mean that IAPV is the only — or even the main — culprit behind CCD, however. Could you tell us about what has been learned since that time about the role IAPV may play in CCD?

Research published in September 2007 showed that among known pathogens, IAPV was the most consistent indicator of CCD. And it was found in at least 19 states. However, Kashmir Bee Virus (KBV), and two microscopic spore parasites — Nosema apis and Nosema ceranae — were also found to be indicators of CCD. Also, no clear cause and effect relationship was found between IAPV and CCD. Not all colonies with IAPV die off, and it’s possible that other stress factors are needed to make IAPV deadly to bee colonies.

Besides IAPV, how has the investigation evolved since last fall in regard to the other potential causes, such as pesticides and varroa mites? What kinds of studies are going on now?

We are in the final stages of receiving individual colony analysis on pathogens and pesticides from the original data set and are analyzing and writing up these results. IAPV cannot explain CCD losses by itself, and other factors are being examined.

Last year we monitored 280 colonies as they moved up and down the East Coast. We are processing this data, to test some predictors of disease based on last year’s studies.

We’ve also discovered some new conditions that seem to be affecting survivorship, and we are trying to figure out what exactly these are.

The effort to look at the impacts of pesticides has reveled a surprisingly large number of different pesticides in pollen, wax, and the bees themselves — and some of these at high levels. These pesticides are used in agriculture and sometimes by the beekeepers themselves. We have initiated investigations into the sub-lethal effects of pesticides, potential synergistic effects of multiple pesticides, the impact of pesticides in combination with other stress factors — like IAPV or varroa mites — and the use of irradiation to mitigate pesticides residues.

In many media reports on CCD, there is a feeling of inevitability that suggests that beekeepers are just waiting for CCD to decimate their hives. What can beekeepers do now?

Beekeepers are advised to practice good hygiene with their hives. For example, they shouldn’t combine weak colonies with stronger ones or exchange colony hardware. This kind of contact can spread diseases. Beekeepers should irradiate “dead-out” equipment — or at least store it for as long as possible — before reusing it with other colonies.

There are also products that beekeepers can use to control other colony stresses, like varroa mites and other parasites. And because nutrition is a concern, beekeepers should make sure their colonies are well fed, especially with a protein supplement.

Many of our viewers are interested in doing whatever they can to help. What would you tell them?

There are many things people can do: become a beekeeper, support beekeepers by buying local honey, plant a pollinator garden, and use less pesticides.

For more information, see “How can you help the bees?“

Honeybee (Apis mellifera)

• Type: Insect
• Family: Apidae
• Habitat: Hollow trees in forest habitats, and beekeeper hives
• Location: Native to Africa and Europe, but spread by humans to temperate and tropical climates worldwide
• Diet: Herbivore
• Average lifespan in the wild: Workers, 15 – 38 days in summer; queen bee, as much as 3 years
• Size: Worker, .5 – .6 in (12 – 15 mm); queen, .7 – .9 in (18 – 22 mm)
• Weight: Worker, .0035 ounces (100 mg); queen and drones, .007 ounces (200 mg)

Like ants and termites, common honeybees, which are black with characteristic orange-yellow rings on the abdomen, are social and cooperative insects. Three different types of bees inhabit a colony: a queen, workers, and drones. The queen bee, which is longer and heavier than worker bees, is the only sexually developed female in the colony; using a specialized organ called an ovipositor, she lays the eggs from which all of the bees in a colony emerge. Worker bees, which forage the flowers in meadows, open woods, gardens, and agricultural fields for pollen and nectar (which is converted into the honey that helps to feed the colony), and build and maintain the hive, are sexually immature females. Their ovipositors are modified into stingers. Male bees, or drones, don’t forage; they may help maintain the temperature of the hive, although their primary role is to fertilize the queen. Because they have no ovipositors, they also don’t have stingers.

Bee colonies are maintained all over the world to pollinate agricultural crops. In the winter of 2006-2007, beekeepers in the United States and other parts of the world began to report the catastrophic loss of colonies, a phenomenon dubbed Colony Collapse Disorder. While the death of some bees in a colony is normal during winter months, the recent number of deaths has been unusually high, with some colonies losing more than 75 percent of their bees. After such devastating die-offs, the colony can no longer sustain itself. Scientists are still trying to explain the phenomenon, which threatens the economic future of the 130 fruit, vegetable, nut, ornamental, and fiber crops in the U.S. pollinated by honeybees.

Did you know? Forager bees will fly about 500 miles before their wings wear out and they die.

Related Episode:

• Silence of the Bees

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Web Sites

Apimondia
http://www.apimondia.org/
Apimondia is the Web site for the International Federation of Beekeepers’ Associations. It promotes scientific, ecological, social, and economic apicultural development. Apimondia encourages cooperation between beekeepers’ associations, scientific bodies, and individuals.

International Bee Research Association
http://www.ibra.org.uk
International Bee Research Association is a charity working to increase awareness of the vital role of bees in the environment and to encourage the use of bees as wealth creator.

Beesource
http://www.beesource.com
Web site with an extensive list of associations; a bee news blog and active forums on topics from apitherapy and natural beekeeping to product reviews and classifieds.

Behoo
http://www.beehoo.com
A directory to over 1,000 sites worldwide, organized by topic and region.

The University of Minnesota Bee Lab
http://www.extension.umn.edu/honeybees
The University of Minnesota Bee Lab is a cutting-edge center of bee research that offers education and courses.

Dadant and Sons
http://www.dadant.com
The home of American Bee Journal, which covers professional concerns.

North American Pollinator Protection Campaign
http://www.nappc.org/
Organization that serves to encourage the health of resident and migratory pollinating animals in North America.

American Beekeeping Federation
http://www.abfnet.org/
The national association that serves the needs of the U.S. beekeeper.

Bee Culture
http://www.beeculture.com
The magazine of American beekeeping.

USDA Bee Research Laboratory
http://www.ars.usda.gov/main/site_main.htm?modecode=12-75-05-00
Bee Research Laboratory’s mission is to conduct research on the biology and control of honeybee parasites, diseases, and pests to ensure an adequate supply of bees for pollination and honey production.

Back Yard Beekeepers Association
http://www.backyardbeekeepers.com/
The BYBA is a non-profit, charitable organization that provides practical information about the “how-tos” of beekeeping. The club also provides the general public with educational programs about honeybees and the benefits of beekeeping in our communities.

Interview with Doug Shultz on the The Alcove with Mark Molaro
http://blip.tv/file/439375
Filmmaker Doug Shultz discusses the filming of Silence of the Bees.

Related Episodes

Nature: Alien Empire
http://www.pbs.org/wnet/nature/alienempire/multimedia/bee.html
Interactive Web site on the world of insects. Includes games on bee anatomy and the inner workings of the hive.

Books

Natural Beekeeping: Organic Approaches to Modern Apiculture By Ross Conrad. Vermont: Chelsea Green Publishing, 2007.

A Book of Bees: And How to Keep Them By Sue Hubbell. New York: Mariner Books, 1998.

The Wisdom of the Hive: The Social Physiology of Honey Bee Colonies By Thomas D. Seeley. Cambridge, Mass.: Harvard University Press, 1995.

The Honey Bee By James L. Gould and Carol Grant Gould. New York: Scientific American Library, 1988.

Honey: A Comprehensive Survey Edited by Eva Crane. London: William Heinemann Ltd, 1975.

ABC and XYZ of Bee Culture: An Encyclopedia Pertaining to Scientific and Practical Culture of Bees By A. I. Root. Medina, Ohio: A. I. Root Co., 1950.