Cover

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Title Page, Copyright

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CONTENTS

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pp. 5-6

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Introduction

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pp. 7-16

Everybody likes bumble bees. As colorful and familiar visitors to flowers, these insects have long been appreciated by artists, naturalists, and farmers. The eighteenth-century German pioneer of pollination biology, Christian Konrad Sprengel, made observations of their behavior at flowers, and Charles Darwin went on to describe their importance as pollinators at a time when this ecological function had not been widely recognized. In North America, naturalists have been describing their diversity for more than two centuries, but a great deal remains to be done. This guide is aimed at making that easier. The value of bumble bees...

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Observing Bumble Bees

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pp. 17-19

Properly identifying a fast-moving bumble bee to species level requires a bit of practice, patience, and some tried-and-true techniques. While a foraging bumble bee is quite docile when busy gathering food from flower to flower, female bumble bees can and will sting if defending their nest or trapped (e.g., under foot, in clothing). Unlike honey bees, which die if they use their strongly barbed sting, bumble bees can often withdraw their weakly barbed sting from skin and use it repeatedly until they are able to escape. However, by being cautious, you will be able to observe bumble bees...

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Attracting Bumble Bees

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pp. 20-21

There are several easy ways to attract a variety of bumble bees and other interesting pollinators to your garden. Not only will you benefit by being able to observe and learn to identify these animals from day to day in your own backyard, but you will also be helping them by providing food and shelter, precious resources in our increasingly altered...

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Bumble Bee Forage Guide by Ecoregion

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pp. 22-28

In the species accounts, we use quotes around “Aster” and “Epilobium” because, although these genera have been split taxonomically, bumble bees forage on all the daughter genera. We cannot tell which genus a collector intended when recording the name of a plant from which a bumble bee was collected...

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Maps and Seasonal Activity

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pp. 29-30

Where and when are the different bumble bee species active? Bumble bees have been a popular research focus of North American students, naturalists, and scientists for more than a century; as a result, thousands of pinned specimens, each with a label describing the details of its collection and identity, can be found in the scientific collections of museums, universities, and government institutions. A recent focus of these institutions has been the digitizing of collections in order to make the data accessible to scientists and the general public. We assembled a database of more than 250,000 digitized...

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Bumble Bee Decline and Conservation

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pp. 31-32

Drastic declines of bee populations have been making newspaper headlines in recent years. Reductions in managed honey bee colonies, an introduced species that pollinates many important agricultural crops, have increased awareness about how much we rely on bees in general for their ecosystem services. Our native bumble bees are also important pollinators of a variety of food crops and have recently been found to be in decline in the wild. Bumble bees excel at pollinating...

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Threats to Bumble Bees

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pp. 33-35

The reason some bumble bee species are declining rapidly while others remain common is the subject of much scientific research. Bumble bee species differ in their seasonal activity, preferred food plants, colony productivity, habitat usage, and other life history traits. These differences may explain differential variability in regard to environmental stressors. According to research so far, it seems unlikely that one stressor is to blame in all situations, and a combination of threats may explain the declines....

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Natural Enemies

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pp. 36-38

Like all insects, bumble bees face predators and parasites that constrain populations in natural ecosystems. Despite having a defensive stinger and warning coloration, bumble bees face numerous natural enemies. Bumble bee colonies are filled with protein- and carbohydrate-rich nectar, pollen, and larvae and are commonly attacked by mammals, including bears, raccoons, and skunks. In flight, a bumble bee may provide a quick snack for a bird. Foraging bumble...

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Mimicry

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pp. 39-42

The eye-catching color patterns of bumble bees, mostly yellow and black, sometimes with red or white or both, serve to remind experienced predators that these bees may produce a painful sting when handled. Other insects, such as flower flies, which lack stingers or other distasteful characteristics, have evolved to look and act like bumble bees, thus gaining a measure of protection from predation through mimicry (see photo page 42) . In a classic case of such em>Batesian mimicry...

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Distinguishing Bumble Bees from Other Insects

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pp. 43-45

Most people are familiar with bumble bees, recognizing their fuzzy, colorful, robust bodies and noisy bumbling flight between flowers. Bumble bees are very hairy bees with combinations of contrasting bright colors, mostly black and yellow, sometimes with various combinations of red or white. They have two pairs of wings that are usually folded back over the abdomen while they are foraging on flowers, or hooked together as a single unit...

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Bumble Bee Names and Classification

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pp. 46-49

The aim of this guide is to help people identify bumble bees to species—that is, to find their correct names. Names are important because these labels, as part of the information retrieval system, allow us to bring together information from different sources on all aspects of each particular species, including their behavior and ecology. For names to work for information retrieval, they have to be standardized. This is the purpose and advantage of formal “Latin” names. People have always given organisms “common” names, but these names...

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How to Use This Book to Identify Bumble Bee Species

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pp. 48-52

The hair (pile or pubescence) of bumble bees has many different color patterns, which may give the impression that species should be easy to identify. Unfortunately it is not that straightforward. Simple keys based on color patterns may appear easy to use, and may work well on small local faunas, but they are unreliable for correct identification at the continent-wide level. Not only do bumble bee color patterns often vary a lot within species, but different species can also look very similar to...

Species Accounts

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pp. 53-53

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SQUARE- OR LONG-CHEEKED BEES WITH A ROUNDED ANGLE ON THE MIDLEG

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pp. 54-112

Western, medium tongue-length species. Most similar to B. caliginosus and em>B. vandykei (see also B. occidentalis, B. franklini, B. fervidus, B. insularis, and B. flavidus). Hand characters Body size medium (larger than B. caliginosus, B. vandykei): queen 18–21 mm (0.69–0.83 inch), worker 8–17 mm (0.33–0.65 inch). Hair short and even. Head length medium with the cheek (oculo-malar area) as long as broad (contrast B. occidentalis, B. franklini, B. fervidus), midleg basitarsus...

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SHORT-CHEEKED BEES WITH A ROUNDED ANGLE ON THE MIDLEG

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pp. 113-137

Eastern and northern, short-tongued species. Most similar to B. occidentalis and B. cryptarum (see also B. pensylvanicus, B. auricomus, and B. nevadensis). Evidence from DNA barcodes supports this as a species separate from B. occidentalis, which it more or less replaces in the east. Hand characters Body size medium: queen 19–21 mm (0.73–0.84 inch), worker 10–15 mm (0.39–0.57 inch). Hair short and even. Head short with the cheek (oculo-malar area) just shorter than broad...

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MEDIUM- OR LONG-CHEEKED BEES WITH A SHARP ANGLE ON THE MIDLEG

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pp. 138-156

Widespread, long-tongued species. Most similar to B. borealis, B. pensylvanicus, B. appositus, B. distinguendus, and B. nevadensis (see also B. vosnesenskii, B. caliginosus, B. vandykei, B. perplexus, B. occidentalis, B. franklini, B. insularis, and B. flavidus). Evidence from DNA barcodes supports a close relationship between individuals with the darker color patterns in the west (named californicus) and individuals....

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HINDLEG (TIBIA) WITH THE OUTER SURFACE UNIFORMLY CONVEX AND DENSELY HAIRY (CUCKOO BUMBLE BEES, NO WORKERS)

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pp. 157-169

Eastern species. Most similar to B. variabilis (see also B. impatiens and B. bimaculatus). The extreme light and dark female color patterns are rare. Hand characters Body size medium: female (no worker) 18–22 mm (0.69–0.87 inch). Hair of the metasoma short (but longer on metasomal T5 than length of last segment of the hind foot) and even. Hindleg tibia with the outer surface convex and densely hairy, lacking a pollen basket (contrast non-cuckoo bumble bees). Hair of the face black, usually with only a minority of yellow hairs intermixed...

Identification Keys to Female and Male Bumble Bees, with Photos

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pp. 170-200

Glossary

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pp. 201-204

Additional Resources

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pp. 205-205

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Acknowledgments

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pp. 206-207

We would like to thank our friends, family, and colleagues who supported us throughout the creation of the book.We are particularly grateful to the following individuals who provided substantial assistance to various aspects of development of this book: Lucy Bailey, Michael Kuhlmann, Vlad Blagoderov, Eugene Morton, Sam Droege, Steve Buchmann, Sarina Jepsen, Laurence Packer, Cory Sheffield, Jonathan Chipman and Russell Galen. Thank you to our reviewers Syd Cannings, Joe Engler, Terry Griswold, David Walter and Stephen Buchmann, as well as one anonymous...

Photo Credits

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pp. 208-208

Index

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pp. 209-210