Bumble Bees 

of the 

Eastern 

United States

By

Sheila Colla

Leif Richardson

Paul Williams

A product of the USDA Forest Service and the Pollinator Partnership

with funding from the National Fish and Wildlife Foundation

United States 

Department of 

Agriculture
2 Bumble Bees of the Eastern United States

Executive Editor Larry Stritch, Ph.D., USDA Forest Service 

Executive and Managing Editor Laurie Davies Adams, The Pollinator Partnership

Graphic Design and Art Direction Marguerite Meyer

Administration Jennifer Tsang, The Pollinator Partnership

Illustrations Alison Boyd, The Pollinator Partnership

IT Production Support Elizabeth Sellers, National Biological Information 

Infrastructure, U.S. Geological Survey

Cover: Male Bombus griseocollis

foraging at cultivated coneflower. 

Photo Leif Richardson
Bumble Bees of the Eastern United States 3

Table of Contents

3 Table of Contents

4 Foreword

5 About the Authors

6 Introduction

10 Bee Diagrams

13 Map Methodology

14 Species Guides (color coded)

14-41 Long- or square-cheeked bees with a rounded angle on the midleg

42-61 Short-cheeked bees with a rounded angle on the midleg

62-77 Long-cheeked bees with a sharp angle on the midleg

78-97 Bees with hindleg outer tibial surface convex and uniformly hairy (cuckoo bumble bees)

98 Identification Key

102 Acknowledgements

103 Web and Other Resources

Guide to

Bumble Bees 

of the 

Eastern 

United States
4 Bumble Bees of the Eastern United States

Home bookshelves, school libraries, 

nature centers, and museum gift shops 

are crowded with dozens of recent field guides to the North American fauna 

and flora. Naturalists, young and old, inexperienced and seasoned professionals, have access to illustrated guides of all types of exciting organisms, 

living and dead. But where are the bee identification field guides? More 

than 4,000 species of native bees in the United States and Canada are 

generally small and lead hidden lives, going mostly unnoticed by almost 

everyone. Bigger bees, like bumble bees and carpenter bees, get noticed, as 

do the omnipresent brown and black-striped worker honey bees. 

Bee identification, including family, genus, and species level, usually involves highly focused specialized training. Bird and butterfly identification 

is comparatively easy, which is why there are more bird watchers than bug 

watchers and why there are almost no guides available for bee identification. The earlier a student of bees adopts professionally recognized scientific 

names for bee groups, the easier it becomes.

Typically in bumble bee identification, voucher specimens must be collected 

and compared side-by-side with museum specimens. The specimen is 

identified using complex professional keys buried in old and hard-to-find 

literature. An anonymous quotation captures the complexity of bee identification: “taxonomic keys are written by individuals who don’t need them for 

others who can’t understand them.” 

The Guide to Eastern Bumble Bees is an indispensible new bumble bee 

identification resource for the Eastern United States. For the first time, 

melittologists (scientists who study bees) Colla, Richardson, and Williams 

provide an easy-to-use illustrated and engaging field guide to the most 

commonly encountered bumble bees. Each bee species has information 

on preferred food plants, nesting biology, and similar species, along with 

the seasonal activity patterns for adults at flowers. Closely cropped color 

photographs illustrate key color patterns and floral behaviors, while macro 

images highlight morphological characteristics and species-level differences. Additionally, there are detailed dot distribution maps and dichotomous 

identification keys for each of the 21 species. The key refers to diagrammatic “torpedo style” color illustrations of the typical colors for castes of 

each species. Much of the information is presented together for the first 

time (e.g., dot distribution maps of species ranges).

This new guide is an authoritative tool for learning about our rich and varied 

bumble bee fauna. This field guide will enable people to identify, name, and 

further explore the colorful and charming bumble bees. This guide encourages exploring nature firsthand from a new perspective. As one young 

scientist said, “I really like bumble bees because they are so fuzzy and cute. 

It’s hard not to like them.” With the Guide to Eastern Bumble Bees, we not 

only admire the Bombus of the East, we can also identify, understand, and 

support them as well. Like the canary in the coal mine, several bumble 

bees of the eastern region (Bombus terricola, Bombus pensylvanicus, and 

especially Bombus affinis) have declined dramatically across their former 

wide distributions in the past decade. With the proper identification tools, 

students and citizen scientists can help professional entomologists track 

their populations and learn why we are losing these essential pollinators.

Stephen Buchmann, Ph.D.

International Coordinator North American Pollinator Protection Campaign 

(NAPPC), Co-author of “The Forgotten Pollinators”

Foreword
Bumble Bees of the Eastern United States 5

Sheila R. Colla has studied various 

aspects of bumble bee ecology, behavior, 

and conservation throughout North 

America. She is currently a doctoral 

student and recipient of the Natural 

Sciences and Engineering Research 

Council Alexander Graham Bell Canadian 

Graduate Scholarship at York University 

under the supervision of Dr. Laurence 

Packer in Toronto, Ontario, Canada. Her 

dissertation examines changes in bumble 

bee communities over the past century 

and looks into some of the causes for 

observed declines. In addition, she is a 

member of the North American Pollinator 

Protection Campaign and her research 

has been featured in The Washington 

Post, Canadian Gardening, The Toronto 

Star, BioScience, CBC’s Quirks and 

Quarks, and The Daily Planet for 

Discovery Channel Canada. 

Email: scolla@yorku.ca

Website: www.savethebumblebees.com

Leif Richardson is a graduate student 

at Dartmouth College, where he is doing 

dissertation research on plants and 

their pollinators. He holds a master’s 

degree from the University of Arizona’s 

Department of Ecology and Evolutionary 

Biology and worked for many years as an 

ecologist with the Vermont Department of 

Fish and Wildlife’s Nongame and Natural 

Heritage Program. He is documenting the 

distribution and decline of bumble bees 

in New England and is involved in efforts 

to conserve bumble bee populations in 

Eastern North America.

Email: leif.l.richardson@dartmouth.edu

Phone: 802-225-6353

Paul Williams studied the distribution 

and decline in British bumble bees for a 

Ph.D. at Cambridge (UK) in 1985. Since 

then, he has continued to work on this 

as a research entomologist at the Natural 

History Museum, London, UK, but is 

looking increasingly at bumble bee 

ecology and systematics worldwide, with 

field work especially in North America, 

the Himalaya, and China. Larger 

taxonomic publications have included 

faunal revisions of the bumble bees 

of Kashmir and more recently on the 

bumble bees of Sichuan, on a checklist 

of bumble bee species of the world, and 

on a series of papers on bumble bee 

phylogeny and subgenera.

Overview: www.nhm.ac.uk/bombus

Publications on bumble bees: www.nhm.

ac.uk/bombus/publications.html

About the Authors

Authors are listed in alphabetical order. Each contributed equally.
6 Bumble Bees of the Eastern United States

The genus Bombus (bumble bee) includes approximately 

250 species found primarily in temperate regions of 

North America, Central America, South America, Europe, 

and Asia. They are absent from Australia, lowland India, 

and from most of Africa. In the United States, in States 

whose boundaries are fully east of the 100th meridian, 

there are a total of 21 species.

The common and easily recognized bumble bees are large 

and furry corbiculate (i.e., they have smooth areas on 

the hindlegs surrounded by stiff bristles for transporting 

pollen) bees with no jugal lobe to the hindwing. All 

species are eusocial except for members of the 

subgenus Psithyrus, which are social parasites that invade 

host bumble bee nests to produce offspring.

Introduction Bumble Bees 

of the 

Eastern 

United States Bumble bee taxonomy 

and biogeography

Phylum Arthropoda, 

Class Insecta, 

 Subclass Pterygota, 

 Order Hymenoptera, 

 Suborder Apocrita, 

 Infraorder Aculeata, 

 Superfamily Apoidea, 

 Family Apidae, 

 Subfamily Apinae, 

 Genus Bombus
Bumble Bees of the Eastern United States 7

Natural History 

Bumble bees have the rare physiological capability 

(among insects) to choose to thermoregulate. They 

are able to generate heat in their thoracic muscles, by 

shivering, to reach the required minimum temperature 

for flight (approx. 30°C). Given that bumble bees fly in 

the spring and fall in temperate regions, this internal 

temperature can be well above ambient temperature.

Bumble bees rely entirely on flowering plants for food. 

Adults feed primarily on nectar for energy to fuel flight, 

but feed their larvae primarily on pollen to provide protein 

for growth. Bumble bees are considered to be generalist 

foragers. Because of the length of their colony cycles, 

bumble bees usually need to feed from a variety of plant 

species, including native wildflowers, crop plants, and 

introduced species. As can be seen in the following 

species pages, there are differences between species in 

timing of emergence, length of colony cycle, foraging 

behavior, and habitat selection.

The length of the bumble bee’s tongue governs its 

food-plant choices, with bees preferring flowers with a 

similar depth to their own tongue length, as this tends 

to maximize the rate at which they can gather nectar. 

Tongue length varies with body size within species, but 

also varies among species. Therefore different bumble 

bee species with different tongue lengths tend to visit 

different food-plant species, resulting in some partitioning 

of food-plant usage among bumble bee species. This may 

have the effect of reducing competition between bumble 

bee species in a community.

The Colony Cycle 

Bumble bees are eusocial organisms with annual colonies 

in North America (i.e., one year = one generation). This 

means bumble bees live in colonies comprised of several 

different ‘castes’ who divide the reproductive, foraging, 
8 Bumble Bees of the Eastern United States

defense, and other tasks necessary to their survival. Reproductive 

females, or ‘queens,’ live with their male and female offspring, 

and all employ an array of physiological and behavioral 

adaptations for communication. Mated queens emerge from 

hibernation in the spring after overwintering and begin feeding. 

Spring queens search for a suitable nest site where they then 

begin their colonies. Eggs hatch after approximately 4 days and 

the small larvae begin to feed on pollen mixed with nectar. The 

larval stage of bumble bees has four instars. After almost 2 weeks 

of development, the larvae spin cocoons and pupate. Pupae 

develop for another 2 weeks before emerging as full-sized adults. 

In total, development takes approximately 5 weeks but this varies 

with temperature and food supply. First, female workers emerge 

and begin foraging for the colony and feeding the brood. As 

the summer progresses, the colony reaches maximum worker 

production and begins producing males and potential queens. 

These reproductive individuals leave the nest and mate. After 

mating, young queens enter diapause and overwinter. The males 

and the rest of the colony die with the onset of cold weather in 

late fall.

Bumble bee species vary according to how they store pollen and 

feed developing larvae. ‘Pollen storers’ accumulate pollen for later 

use, often re-using vacated cocoons for this (e.g., B. terricola). 

The queen and workers feed each larva individually, opening their 

brood cells to regurgitate a mixture of pollen and nectar for them. 

By contrast, ‘pocket makers’ place pollen directly in a wax pocket 

on the side of a group of larval cells (e.g., B. fervidus). The larvae 

of these species all feed from the same pocket, which sometimes 

leads to greater size differences in adult bees of the same caste.
Bumble Bees of the Eastern United States 9

Bumble bee species belonging to the subgenus Psithyrus

are an exception as they do not produce a worker caste, 

but are social parasites. Females usurp colonies of other 

species and reproduce using the host species’ resources. In 

the eastern fauna, the parasitic species are: B. ashtoni, B. 

citrinus, B. fernaldae, B. insularis, B. variabilis.

Importance in 

Natural Ecosystems 

and Agriculture

Bumble bees are extremely important pollinators for 

agriculture both in the field and in greenhouses. Unlike 

honey bees, they are able to forage under cold, rainy, and 

cloudy conditions. This makes them excellent pollinators 

for a variety of crops in temperate regions. Some crops 

that bumble bees can pollinate include tomatoes, 

peppers, raspberries, blueberries, chives, cucumbers, 

apples, strawberries, alfalfa, blackberries, soybeans, 

sunflowers, beans, cherries, apricots, plums, almonds, 

nectarines, peaches, rosehips, eggplants, and cranberries.

Bumble bees are also extremely important pollinators of 

many flowering plants throughout the native ranges with 

which they co-evolved mutualisms where they receive 

food in return for providing pollination. Bumble bees are 

generalists and have been recorded visiting hundreds of 

native plant species. The pollination services bumble 

bees provide for native plants are likely very important 

for maintaining various ecosystems. In addition, other 

animals, like small mammals and birds, rely on the fruits 

and seeds of pollinated plants for food. 

Bumble Bee Declines 

We have evidence that in North America some of 

our bumble bee species are declining and a few are 

threatened with extinction. One species from Oregon 

and California (Franklin’s bumble bee) has recently been 

listed by the International Union for Conservation of 

Nature (IUCN) as Critically Endangered. Species that 

seem most vulnerable are those with smaller climate 

tolerances, those at the edge of their climatic niches, 

and later emerging species. In North America, members 

of the subgenus Bombus sensu strictu (i.e., B. affinis, 

B. occidentalis, B. franklini, B. terricola) seem to be 

declining at a rapid rate.

Currently, the suspected threats to wild bumble bees are:

habitat loss due to agricultural intensification, 

urbanization or pollution, 

pesticide use, 

pathogen spillover from managed bees, 

and climate change.
10 Bumble Bees of the Eastern United States

Bee Body Diagram

thorax

head

foreleg

midleg

hindleg

wings 1

2

3

4

5

6 abdomen

(with 

numbered 

terga/ “T”

corbiculum/

pollen basket

Bombus ternarius, queen

antenna
Bumble Bees of the Eastern United States 11

Bee Leg Diagram

midleg

femur

tibia tarsal segments

basitarsus

hindleg

Bombus bimaculatus, male
12 Bumble Bees of the Eastern United States

Bee Face Diagram

ocelli

antenna

clypeus

tongue

cheek (malar space)

mandible

compound eye

supraorbital line

Bombus sandersoni, worker
Bumble Bees of the Eastern United States 13

Map Methodology

The maps produced for this guide provide two sets of information 

about the range of each species: points that represent actual bumble 

bee collections, and generalized range polygons meant to predict bee 

distribution in areas where we lack specimen collection data. Many 

institutions and individuals have contributed digitized, georeferenced 

specimen data to this effort, and dots on each map represent 

collections held by the following: 

Sheila Colla, York University

Paul Williams, British Natural History Museum

Leif Richardson, Vermont Department of Fish and Wildlife

Caroline Scully, Antioch University New England

John Ascher, American Museum of Natural History

Ohio State University Hymenoptera Online Database

Illinois Natural History Survey

Yale University, Peabody Museum

University of Connecticut Insect Collections

University of Vermont’s Zadock Thompson Zoology Collection

Canadian National Collection of Insects

Rachael Winfree, Rutgers University

Sam Droege, U.S. Geological Survey, Patuxent Wildlife Research 

Center

Michael Arduser, Missouri Department of Conservation

H.E. Milliron (published records from various collections)

Kevin Matteson, Fordham University

Steve Marshall, University of Guelph

Many other insect collections exist that have not been checked for 

identification accuracy or digitized. These maps can thus be improved 

upon as more data become available.

Maps are at a scale of 1:11,000,000. For each species, a range 

polygon (shown in green) was produced by buffering specimen 

collection points by 100 kilometers, then merging all buffers together. 

We chose this as an arbitrary distance from known locations of 

occurrence (i.e., sites where specimens have been collected) because, 

in general, we believe that it helps to describe a bumble bee species’ 

range. Minor changes were made to the resulting layer to connect 

adjacent polygons where we thought it appropriate, to smooth some 

edges and to improve the presentation of the map. The range polygon 

layer was then clipped to the Eastern United States. No range polygon 

was made for B. frigidus, because we currently know of just one 

specimen of this bee collected in the Eastern United States.

For each species, the specimen collection points from the Eastern 

United States are displayed. Data from most sources listed above are 

termed ‘Primary Records,’ because we have high confidence in the 

determinations (identifications) of those specimens. Data from the 

Ohio State University collection are termed ‘Other Records,’ because 

we have not verified the determinations of bees in that collection. In a 

few cases, we have also displayed points on the maps that represent 

photographs of bumble bees, not actual collections. We have only done 

this when accurate identification was possible from a photo.

For three species that have undergone precipitous declines in the last 

decade—B. affinis, B. terricola, and B. ashtoni—we chose to display 

the relatively few collections made after 1997 differently from all 

those made previously. This is intended to give the reader a sense of 

how much the species’ ranges have shrunk and where they might still 

be found.

Range information is shown for all full States east of the 100° 

longitude line. Users should bear in mind that most of the bumble 

bees found in this area also occur in parts of adjacent Canada and the 

Western United States.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

14 Bumble Bees of the Eastern United States

Bombus impatiens worker foraging on cultivated sunflower

Photo Leif Richardson

Common eastern bumble bee

• Common, possibly expanding range

• Select food plants: Cirsium (Thistles), Eupatorium, Gelsemium, 

Solidago (Goldenrods), Pontederia (Pickerel Weeds)

• Tongue length: medium

• Nests underground

• Parasitized by B. citrinus

• Can be confused with B. bimaculatus

Bombus impatiens
Long- or square-cheeked bees with 

a rounded angle on the midleg

Bumble Bees of the Eastern United States 15

Lateral image of a female Bombus impatiens.

Photo Sheila Colla

Bombus impatiens

male on aster.

Photo Sheila Colla

Bombus impatiens queen foraging on clover.

Photo Sheila Colla

Bombus impatiens male on oregano. 

Photo Leif Richardson

Female Bombus impatiens 

face. Photo Sheila Colla

Bombus impatiens continued
16 Bumble Bees of the Eastern United States

Bombus impatiens continued
Bumble Bees of the Eastern United States 17

Bombus impatiens continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax and T1 predominantly pale yellow, some black 

hairs intermixed between the wing bases, 

T2 entirely black, tail black.

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek as long as broad. Hair of the face 

black or with only a few yellow hairs intermixed, black 

hairs intermixed diffusely between the wing bases, 

hair of T2 always entirely black. Hair short, metasoma 

rather long and rectangular. 
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

18 Bumble Bees of the Eastern United States

Male Bombus bimaculatus foraging at wild bergamot. 

Photo Leif Richardson

Two-spotted bumble bee

• Common

• Select food plants: Cirsium (Thistles), 

Hypericum (St. John’s Wort),

Melilotus (Sweet Clovers), Rosa, Solidago (Goldenrods), 

Vicia (Vetches)

• Tongue length: medium

• Nests underground and on surface

• Can be confused with B. impatiens, B. griseocollis,

Bombus bimaculatus
Bumble Bees of the Eastern United States 19

Lateral image of a female 

Bombus bimaculatus.

Photo Sheila Colla

Bombus bimaculatus queen foraging for 

nectar from cultivated azaleas.

Photo Leif Richardson

Bombus bimaculatus worker. 

Photo Sheila Colla

Bombus bimaculatus face.

Photo Sheila Colla

Bombus bimaculatus continued
20 Bumble Bees of the Eastern United States

Bombus bimaculatus continued
Bumble Bees of the Eastern United States 21

Bombus bimaculatus continued

Females (queens and workers, colors refer to pile or ‘hair’): 

• Thorax and T1 predominantly yellow, a black spot between the 

wing bases, T2 usually with a yellow W in the middle, tail black, 

hair long.

• Midleg basitarsus with the distal posterior corner rounded. 

Cheek slightly longer than broad. Hair of face black or with only 

a few yellow hairs intermixed, black hair of the spot between 

the wing bases dense and always present, although often 

with yellow hairs intermixed, the black hairs only occasionally 

forming a band between the wing bases, T2 always 

with some yellow hairs present but sometimes with 

very few, although if the yellow is extensive then 

black hairs are intermixed posteriorly and medially 

and the posterior margin of the yellow usually forms a 

characteristic W-shape (which may be similar in some 

B. griseocollis, although that species usually has some 

yellow hairs rather than black anterio-laterally). Hair 

long and uneven, metasoma 

rather short and globular.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

22 Bumble Bees of the Eastern United States

Bombus perplexus worker foraging on St. John’s Wort. 

Photo Leif Richardson

Confusing bumble bee

• Common

• Select food plants: Hydrangea, Rhododendron, Rubus, 

Vaccinium, Lonicera (Honeysuckles), Prunus, Ribes

• Tongue length: medium

• Nests on ground surface and in hollow logs and trees

• Can be confused with B. vagans

Bombus perplexus
Bumble Bees of the Eastern United States 23

Lateral image of a female Bombus perplexus.

Photo Sheila Colla

Bombus perplexus queen.

Photo Leif Richardson

Bombus perplexus male.

Photo Sheila Colla

Female Bombus perplexus face.

Photo Sheila Colla

Bombus perplexus continued
24 Bumble Bees of the Eastern United States

Bombus perplexus continued
Bumble Bees of the Eastern United States 25

Bombus perplexus continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax and T1-2 predominantly brown or yellow, sides 

of the thorax often black, tail black or often with some 

white hairs.

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek slightly longer than broad. Hair of 

the face black or with yellow hairs intermixed, only 

a very few inconspicuous black hairs in the centre of 

the thoracic dorsum between the wing bases, sides 

of the thorax often but not always extensively black, 

sometimes entirely yellow. Pale hair often brownish 

rather than yellow, T5 sometimes with white hair. 

Hair long.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

26 Bumble Bees of the Eastern United States

A worker Bombus vagans visits red clover.

Photo Leif Richardson

Half-black bumble bee

• Common

• Select food plants: Penstemon (Beard-Tongues), 

Asclepias (Milkweeds), Asters, Cirsium (Thistles), 

Eupatorium, Spirea (Meadowsweet), 

• Tongue length: medium

• Nests on ground surface and underground

• Unlike most bumble bees, this species readily forages 

in heavily shaded areas within forests

• Can be confused with B. sandersoni, B. perplexus, 

B. affinis

• Parasitized by B. citrinus

Bombus vagans
Bumble Bees of the Eastern United States 27

Lateral image of a Bombus vagans female.

Photo Sheila Colla

Female Bombus vagans face.

Photo Sheila Colla

Bombus vagans continued
28 Bumble Bees of the Eastern United States

Bombus vagans continued
Bumble Bees of the Eastern United States 29

Bombus vagans continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax and T1-2 predominantly yellow, a black spot 

between the wing bases, sides of the thorax yellow, tail 

black, face long.

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek slightly longer than broad. Hair of the 

face black or with yellow hairs intermixed, the black 

thoracic spot between the wing bases may be small and 

intermixed with yellow hairs in queens but is larger and 

more diffuse in workers, forming a band between the 

wing bases, T2 yellow or sometimes with black along the 

posterior margin, sometimes intermixed laterally, but not 

anteriorly unless the yellow band is very narrow. Hair 

long. Body size small, but larger than B. sandersoni.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Workers

Queens

Males

30 Bumble Bees of the Eastern United States

Bombus sandersoni female in Newfoundland, Canada. 

Photo Cory Sheffield

Sanderson bumble bee

• Uncommon

• Select food plants: Epilobium, Monarda (Bee Balms), 

Penstemon (Beard Tongues), Rubus, Malus (Apples)

• Tongue length: short

• Often confused with B. perplexus and B. vagans. 

Difficult to properly identify and this ecology poorly known.

Bombus sandersoni
Bumble Bees of the Eastern United States 31

Lateral image of a Bombus sandersoni female.

Photo Sheila Colla

Lateral image of Bombus sandersoni female, dark morph.

Photo Sheila Colla

Female Bombus sandersoni face.

Photo Sheila Colla

Bombus sandersoni continued
32 Bumble Bees of the Eastern United States

Bombus sandersoni continued
Bumble Bees of the Eastern United States 33

Bombus sandersoni continued

Females (queens and workers, colors 

refer to pile or ‘hair’):

• Thorax and T1-2 predominantly 

yellow, or with a black spot or band 

between the wing bases, sides 

of the thorax yellow, tail black or 

yellow or occasionally white (not 

orange), face round.

• Midleg basitarsus with the distal 

posterior corner rounded. Cheek 

as long as, or slightly shorter than, 

broad. Hair of the face and top of 

the head black or with yellow hairs, 

corbicular fringes black or with 

brownish-orange tips, T2 anteriolaterally often with a few scattered 

black hairs intermixed, T5 black, 

brown, yellow, or white, with a few 

black hairs intermixed. Hair short 

and even, body size small and 

smaller than B. vagans.
The phenology for this species is unknown due to few records in the Eastern United States.

34 Bumble Bees of the Eastern United States

Bombus frigidus worker on senecio sp.

Photo Jessica Forrest

Bombus frigidus

• Rare in the United States (recorded only in northern border 

States)

• Select food plants: Cirsium (Thistles), 

Epilodium Geranium, Mertensia (Bluebells), 

Taraxacum officinale (Dandelion), Trifolium (Clovers)

• Tongue length: short

Bombus frigidus
Bumble Bees of the Eastern United States 35

Lateral image of a female Bombus frigidus.

Photo Sheila Colla

Female Bombus frigidus face.

Photo Sheila Colla

Bombus frigidus continued
36 Bumble Bees of the Eastern United States

Bombus frigidus continued
Bumble Bees of the Eastern United States 37

Bombus frigidus continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax and T1-2 predominantly yellow, with a black 

band between the wing bases, sides of the thorax 

yellow, tail orange (occasionally faded to more 

yellowish).

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek as long as broad. Hair of the face 

black or with some yellow hairs, corbicular fringes 

extensively pale orange, T2 anterio-laterally without 

scattered black hairs intermixed. Hair long. 
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

38 Bumble Bees of the Eastern United States

Bombus ternarius queen visits dandelion.

Photo Leif Richardson

Tri-colored bumble bee

• Common

• Select food plants: Asclepias (Milkweeds), Rubus, Solidago

(Goldenrods), Rhododendron, Vaccinium 

• Tongue length: short

• Nests underground

• Can be confused with the red color morph of B. rufocinctus

Bombus ternarius
Bumble Bees of the Eastern United States 39

Lateral image of a Bombus ternarius female.

Photo Sheila Colla

A Bombus ternarius worker 

vists cultivated bush pea.

Photo Leif Richardson

Female Bombus ternarius face.

Photo Sheila Colla

Male Bombus ternarius on 

Canada goldenrod.

Photo Sheila Dumesh

Bombus ternarius continued
40 Bumble Bees of the Eastern United States

Bombus ternarius continued
Bumble Bees of the Eastern United States 41

Bombus ternarius continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax and T1 predominantly yellow, with a black band 

between the wing bases extending posteriorly in the 

middle of the scutellum, T2-3 orange, T4 yellow, T5 

black, and with face round.

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek very slightly shorter than broad. 

Hair of face and top of the head black with patches 

of yellow, or sometimes with black more extensively 

intermixed, especially for workers. Thoracic anterior 

band usually yellow without black hairs intermixed 

except in some workers, which have the anterior margin 

of the black band between the wing bases always 

sharply defined. Scutellum with yellow patches entirely 

divided by a black, posteriorly directed triangle. T2 

red, at most with a few black hairs anterio-medially; T4 

yellow; T5 black. Hair short and even.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

42 Bumble Bees of the Eastern United States

Bombus terricola worker collecting nectar from milkweed. 

Photo Leif Richardson

Yellow-banded bumble bee

• Uncommon, possibly declining since the mid-1990s

• Select food plants: Vaccinium, Salix (Willows), Rosa (Roses), 

Rubus, Lonicera (Honeysuckles), Solidago (Goldenrods), Asters

• Tongue length: short

• Nests underground

• Nectar robber

• Parasitized by B. ashtoni

• Can be confused with B. pensylvanicus

Bombus terricola
Short-cheeked bees with a 

rounded angle on the mid leg

Bumble Bees of the Eastern United States 43

Lateral image of a female Bombus terricola.

Photo Sheila Colla

Bombus terricola male forages on hop clover.

Photo Leif Richardson

Bombus terricola worker visiting purple flowering raspberry. 

Photo Leif Richardson

Female Bombus terricola face.

Photo Sheila Colla

Bombus terricola continued
44 Bumble Bees of the Eastern United States

Bombus terricola continued
Bumble Bees of the Eastern United States 45

Bombus terricola continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax with yellow band(s), T1 black, T2-3 yellow, tail 

black or yellow, face round.

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek length slightly shorter than breadth, 

clypeus strongly swollen in the dorsal half, hind 

basitarsus with the posterior margin strongly and evenly 

arched. Hair of the head black or with a minority of 

short pale hairs intermixed. Hair short and even.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

46 Bumble Bees of the Eastern United States

Bombus affinis worker on spotted knapweed. 

Pinery Provincial Park, Ontario. 

Photo Sheila Colla

Rusty-patched bumble bee

• Rare after 1997, previously common

• Select food plants: Helianthus (Sunflowers), Asters, Solidago

(Goldenrods), Lonicera (Honeysuckles), Vaccinium, 

Prunus, Aesculus

• Tongue length: short

• Nests underground

• Occasional nectar robber

• Parasitized by B. ashtoni

• Can be confused with B. citrinus, B. griseocollis, 

B. perplexus, B. vagans

Bombus affinis
Bumble Bees of the Eastern United States 47

Lateral image of a queen Bombus affinis.

Photo Sheila Colla

Lateral image of Bombus affinis worker.

Photo Sheila Colla

Queen Bombus affinis face.

Photo Sheila Colla

Bombus affinis continued
This map, and all subsequent species 

maps, provide two sets of information 

about the range of each species: points 

that represent actual bumble bee 

collections, and generalized range polygons 

meant to predict bee distribution in areas 

where we lack specimen collection data. 

Many institutions and individuals have 

contributed digitized, georeferenced 

specimen data to this effort, and dots 

on each map represent many collections 

which are listed on page 13 under Map 

Methodology along with more information 

about the maps for each species.

48 Bumble Bees of the Eastern United States

Bombus affinis continued
Bumble Bees of the Eastern United States 49

Bombus affinis continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax and T1-2 predominantly yellow, or with a 

black spot or band between the wing bases, T2 often 

distinctly brown in workers, tail black.

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek length slightly shorter than breadth, 

clypeus strongly swollen in the dorsal half, hind 

basitarsus with the posterior margin strongly and evenly 

arched. Hair of the face black, hair of the top of the 

head black or with only a few yellow hairs intermixed. 

Hair of medium length and even.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

50 Bumble Bees of the Eastern United States

Male Bombus griseocollis foraging at cultivated coneflower. 

Photo Leif Richardson

Brown-belted bumble bee

• Common

• Select food plants: Asclepias (Milkweeds), Cirsium (Thistles), 

Helianthus (Sunflowers), Solidago (Goldenrods), 

Rhus (Sumacs), Lythrum (Loosestrifes) 

• Tongue length: medium

• Nests on ground surface 

• Can be confused with B. bimaculatus, B. affinis

Bombus griseocollis
Bumble Bees of the Eastern United States 51

Lateral image of a female Bombus griseocollis.

Photo Sheila Colla

Bombus griseocollis workers foraging on prickly pear.

Photo Leif Richardson

A Bombus griseocollis worker captured by a crab spider. 

Photo Sheila Colla

Bombus griseocollis face.

Photo Sheila Colla

Bombus griseocollis continued
52 Bumble Bees of the Eastern United States

Bombus griseocollis continued
Bumble Bees of the Eastern United States 53

Bombus griseocollis continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax and T1 predominantly yellow, or with a black 

spot between the wing bases; T2 with a yellow or 

brown crescent anteriorly, tail black, hair short.

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek length distinctly shorter than breadth, 

ocelli large. Hair of the face and of the top of the 

head black or with only a few yellow hairs intermixed, 

black thoracic spot between the wing bases often 

very small and inconspicuous but dense. Sometimes 

workers have the yellow on T2 extending for threequarters of the length of T2 and forming a W-shape 

(similar to B. bimaculatus, but with few black hairs 

intermixed medially and some yellow hairs intermixed 

anterio-laterally). Hair very short and even, the 

metasoma rather rectangular and slightly flattened.
54 Bumble Bees of the Eastern United States

Bombus fraternus worker.

Photo Paul Williams

Southern plains bumble bee

• Uncommon

• Select food plants: Hypericum (St. John’s Worts), 

Monarda (Bee Balms), Rhus (Sumacs), 

Solanum (Nightshades and relatives), Asters, 

Cirsium (Thistles) 

• Tongue length: short

• Can be confused with B. affinis, B. griseocollis

Bombus fraternus

Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males
Bumble Bees of the Eastern United States 55

Lateral image of a female Bombus fraternus.

Photo Sheila Colla

Female Bombus fraternus face.

Photo Sheila Colla

Bombus fraternus continued
56 Bumble Bees of the Eastern United States

Bombus fraternus continued
Bumble Bees of the Eastern United States 57

Bombus fraternus continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Thorax and T1-2 extensively yellow, with a black band 

between the wing bases, tail black, hair very short.

• Midleg basitarsus with the distal posterior corner 

rounded. Cheek length much shorter than breadth, 

ocelli large, hind basitarsus with the posterior margin 

almost parallel to the anterior margin. Hair distinctive 

for being very short and even, and on the metasoma 

decumbent, the metasoma nearly rectangular and 

slightly flattened. 
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

58 Bumble Bees of the Eastern United States

A black color morph Bombus rufocinctus worker forages at teasel. 

Photo Leif Richardson

Red-belted bumble bee

• Common 

• Select food plants: Trifolium (Clovers), Melilotus (Sweet Clovers), 

Cirsium (Thistles), Solidago (Goldenrods), Eupatorium, Asters

• Tongue length: short

• Nests underground and on ground surface

• Highly variable in coloration and can be confused with 

many species

Bombus rufocinctus
Bumble Bees of the Eastern United States 59

Lateral image of a Bombus rufocinctus female, black morph.

Photo Sheila Colla

Bombus rufocintus female.

Photo Leif Richardson

A red color morph Bombus rufocinctus worker forage 

at teasel. Photo Leif Richardson

Lateral image of a Bombus rufocinctus female, red morph.

Photo Sheila Colla

Female Bombus rufocintus face.

Photo Sheila Colla

Bombus rufocinctus continued
60 Bumble Bees of the Eastern United States

Bombus rufocinctus continued
Bumble Bees of the Eastern United States 61

Bombus rufocinctus continued

Females (queens and workers, colors 

refer to pile or ‘hair’):

• Similar to many color patterns 

shown by the other Eastern North 

American species, but small 

bodied, short haired, and with a 

short face.

• Midleg basitarsus with the 

distal posterior corner rounded. 

Cheek length distinctly shorter 

than breadth. Many other 

combinations of these color 

patterns are known, but the hair 

of T2 is almost always with at 

least a yellow crescent anteriorly 

(only rarely very much reduced). 

Hind basitarsus with the posterior 

margin evenly but not strongly 

arched. Hair short and even, body 

size small.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

62 Bumble Bees of the Eastern United States

Bombus fervidus female. 

Photo Leif Rchardson

Yellow bumble bee

• Uncommon, possibly in decline

• Select food plants: Lonicera (Honeysuckles), 

Cirsium (Thistles), Trifolium (Clovers), 

Penstemon (Beard-tongues), Lythrum (Loosestrifes), 

Vicia (Vetches), Monarda (Bee balms)

• Tongue length: long

• Nests on ground surface and underground

• Can be confused with B. borealis

• More common in open fields and meadows

Bombus fervidus
Long-cheeked bees with a 

sharp angle on the midleg

Bumble Bees of the Eastern United States 63

Lateral image of a Bombus fervidus female.

Photo Sheila Colla

Female Bombus fervidus face.

Photo Sheila Colla

Bombus fervidus continued
64 Bumble Bees of the Eastern United States

Bombus fervidus continued
Bumble Bees of the Eastern United States 65

Bombus fervidus continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Face black, thorax and T1-4 predominantly yellow, 

usually with a black band between the wing bases, 

sides of the thorax usually yellow, T5 black.

• Midleg basitarsus with the distal posterior corner 

sharply pointed. Cheek distinctly longer than broad, 

clypeus surface rough with many large punctures. 

Hair of the head black or with only a minority of short 

pale hairs intermixed, sides of the thorax yellow at 

least in the dorsal half (often throughout), black band 

between the wing bases may be very narrow (anterior to 

posterior) and may have many yellow hairs intermixed. 

Hair of medium length and even.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

66 Bumble Bees of the Eastern United States

Bombus borealis male foraging at red clover. 

Photo Leif Richardson

Northern amber bumble bee

• Uncommon

• Select food plants: Vicia (Vetches), Cirsium (Thistles), Asters, 

Prunella, Symphytum officinale (Comfrey), Eupatorium

• Tongue length: long

• Nests underground

• Can be confused with B. fervidus

Bombus borealis
Bumble Bees of the Eastern United States 67

Lateral image of a female Bombus borealis.

Photo Sheila Colla

Bombus borealis males 

on thistle.

Photo Leif Richardson

Bombus borealis worker foraging at culitivated monkshood.

Photo Leif Richardson

Bombus borealis queen foraging on cow vetch. 

Photo Paul Williams

Bombus borealis face.

Photo Sheila Colla

Bombus borealis continued
68 Bumble Bees of the Eastern United States

Bombus borealis continued
Bumble Bees of the Eastern United States 69

Bombus borealis continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Face yellow, thorax and T1-4 extensively yellow, with a 

black band between the wing bases, lower sides of the 

thorax usually black, T5 black or yellow.

• Midleg basitarsus with the distal posterior corner 

sharply pointed. Cheek distinctly longer than broad, 

clypeus surface very smooth and shiny with only a 

few very small punctures near the center. Hair of 

the face usually gray-yellow and usually paler than 

on the rest of the body and only rarely with many 

black hairs extensively intermixed, sides of the thorax 

predominantly black with yellow only within the dorsal 

half. Hair of medium length and even.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

70 Bumble Bees of the Eastern United States

Bombus pensylvanicus worker foraging on cow vetch.

Photo Paul Williams

American bumble bee

• Uncommon, possibly in decline

• Select food plants: Vicia (Vetches), Lotus corniculata, 

Trifolium (Clovers), Solidago (Goldenrods), 

Hypericum (St. John’s Wort), Eupatorium

• Tongue length: long

• Nests on ground surface

• Can be confused with B. terricola and B. auricomus

• Parasitized by B. variabilis

Bombus pensylvanicus
Bumble Bees of the Eastern United States 71

Lateral image of a female Bombus pensylvanicus.

Photo Sheila Colla

Female Bombus pensylvanicus face.

Photo Sheila Colla

Bombus pensylvanicus continued
72 Bumble Bees of the Eastern United States

Bombus pensylvanicus continued
Bumble Bees of the Eastern United States 73

Bombus pensylvanicus continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Top of the head black, thorax with yellow band(s), T1 

often yellow especially in the middle, T2-3 yellow, tail 

black, face long.

• Midleg basitarsus with the distal posterior corner 

sharply narrowly produced and spinose, hind basitarsus 

with the proximal posterior process long and pointed 

(longer than broad). Cheek slightly longer than broad, 

clypeus with large punctures except on the mid line. 

Hair on the top of the head always black, T1 with 

yellow hairs more frequent medially. Hair short and 

even.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Queens

Workers

Males

74 Bumble Bees of the Eastern United States

Bombus auricomus worker foraging on a legume.

Photo Paul Williams

Black and gold bumble bee

• Uncommon

• Select food plants: Monarda (Bee balm), 

Solanum (Nightshades and relatives), Trifolium (Clovers), 

Hypericum (St. John’s Wort), Eupatorium

• Tongue length: long 

• Nests underground

• Can be confused with B. pensylvanicus, B. terricola

Bombus auricomus
Bumble Bees of the Eastern United States 75

Lateral image of a female Bombus auricomus.

Photo Sheila Colla

Female Bombus auricomus face.

Photo Sheila Colla

Bombus auricomus continued
76 Bumble Bees of the Eastern United States

Bombus auricomus continued
Bumble Bees of the Eastern United States 77

Bombus auricomus continued

Females (queens and workers, colors refer to pile or ‘hair’):

• Top of the head yellow, thorax with yellow band(s), T1 

often yellow especially laterally, T2-3 yellow, tail black, 

face long.

• Midleg basitarsus with the distal posterior corner acute 

but not narrowly produced, hind basitarsus with the 

proximal posterior process broad and blunt (shorter 

than broad). Cheek slightly longer than broad, ocelli 

large, mandible with anterior keel not reaching the 

distal margin, clypeus very evenly covered with small 

punctures. Hair on the face black, occasionally with 

a few yellow hairs intermixed; top of the head usually 

yellow, sometimes with black hairs intermixed but 

occasionally predominantly black; T1 with yellow hairs 

more frequent laterally. Hair very short and even.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Females

Males

78 Bumble Bees of the Eastern United States

Bombus citrinus male on Woodland Sunflower.

Photo Sheila Colla

Lemon cuckoo bumble bee

• Common

• Select food plants: Asclepias (Milkweeds), Rubus, 

Verbena (Vervains), Eupatorium, Trifolium (Clovers), 

Solidago (Goldenrods)

• Hosts: B. impatiens and B. vagans

• Can be confused with B. affinis, B. perplexus, B. vagans

Bombus citrinus
Bees with hindleg outer tibial surface convex 

and uniformly hairy (cuckoo bumble bees)

Bumble Bees of the Eastern United States 79

Lateral image of a female Bombus citrinus.

Photo Sheila Colla

Female Bombus citrinus.

Photo J. Lucier

Female Bombus citrinus face.

Photo Sheila Colla

Bombus citrinus continued
80 Bumble Bees of the Eastern United States

Bombus citrinus continued
Bumble Bees of the Eastern United States 81

Bombus citrinus continued

Females (no workers, colors refer to pile or ‘hair’):

• Thorax predominantly yellow, including the 

lower sides, T4-5 black.

• Hind tibia with the outer surface convex and 

densely hairy. Hair of the face black, usually 

with only a minority of yellow hairs intermixed; 

yellow hair above the base of the antenna rarely 

dense. Sides of the thorax entirely yellow; 

thoracic dorsum usually without black hair, but 

if present, then not forming a band between 

the wing bases. T4-5 predominantly black. 

Wings light brown, hair on the metasoma short 

(but longer on T5 than length of last joint of 

hind tarsus) and even, T6 matte with dense 

punctures.
Because of the extreme scarcity of this species, natural history and 

ecology details are not well known. Photos of this species in the wild 

are also scarce.

82 Bumble Bees of the Eastern United States

Variable cuckoo bumble bee

• Extremely rare, possibly extinct

• Select food plants: Asclepias (Milkweeds), Aster, 

Cirsium (Thistles), Solidago (Goldenrods), Eupatorium, 

Trifolium (Clovers) 

• Parasitizes B. pensylvanicus

Bombus variabilis

Female Bombus variabilis.

Photo Sheila Colla
Bumble Bees of the Eastern United States 83

Lateral image of a Bombus variabilis female.

Photo Sheila Colla

Female Bombus variabilis face.

Photo Sheila Colla

Bombus variabilis continued
84 Bumble Bees of the Eastern United States

Bombus variabilis continued
Bumble Bees of the Eastern United States 85

Bombus variabilis continued

Females (no workers, colors refer to pile or ‘hair’):

• Face black, thorax extensively yellow, but the lower 

sides black, tail usually black, hair very short.

• Hind tibia with the outer surface convex and densely 

hairy. Hair of the face black with only a minority of pale 

hairs above the base of the antenna. Sides of the thorax 

predominantly black, thoracic dorsum usually with black 

hair, hair on the metasoma usually black. Wings dark 

brown, hair on the metasoma very short (shorter on T5 

than the length of the last joint of the hind tarsus) and 

even. T6 shiny with sparse punctures.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Females

Males

86 Bumble Bees of the Eastern United States

Female Bombus insularis.

Photo Sheila Colla

Indiscriminate bumble bee

• Rare in the Eastern United States.

• Select food plants: Solidago (Goldenrods), 

Melilotus (Sweet Clovers), Vaccinium, Trifolium (Clovers) 

• Tongue length: short

• Hosts: B. pensylvanicus, B. rufocinctus,

B. ternarius, and B. terricola

• Can be confused with B. fernaldae

Bombus insularis
Bumble Bees of the Eastern United States 87

Lateral image of a female Bombus insularis.

Photo Sheila Colla

Female Bombus insularis face.

Photo Sheila Colla

Bombus insularis continued
88 Bumble Bees of the Eastern United States

Bombus insularis continued
Bumble Bees of the Eastern United States 89

Bombus insularis continued

Females (no workers, colors refer to pile or ‘hair’):

• Face yellow, a black band between the wing 

bases, tail with some yellow.

• Hind tibia with the outer surface convex and 

densely hairy. Hair of the face with a dense 

yellow patch above the base of the antenna, 

sometimes some yellow below the base of the 

antenna but predominantly black. Black hair 

forming a band between the wing bases, sides of 

the thorax yellow anteriorly but black ventrally and 

posteriorly. T3 always with black hair along the 

entire midline but yellow laterally, T4 extensively 

yellow laterally. Wings light brown.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Females

Males

90 Bumble Bees of the Eastern United States

Female Bombus ashtoni.

Photo Sheila Colla

Ashton cuckoo bumble bee

• Rare, possibly in decline since the mid-1990s

• Select food plants: Vaccinium, Trifolium (Clovers), Rubus, 

Melilotus (Sweet clover), Solidago (Goldenrods) 

• Hosts: B. affinis, B. terricola

Bombus ashtoni
Bumble Bees of the Eastern United States 91

Lateral image of a Bombus ashtoni female.

Photo Sheila Colla

Female Bombus ashtoni face.

Photo Sheila Colla

Bombus ashtoni continued
92 Bumble Bees of the Eastern United States

Bombus ashtoni continued
Bumble Bees of the Eastern United States 93

Bombus ashtoni continued

Females (no workers, colors refer to pile or ‘hair’):

• Face black, tail with some white.

• Hind tibia with the outer surface convex and 

densely hairy. Hair of the face and the top of 

the head black, occasionally with some yellow 

hairs at the posterior of the top of the head. 

Sides of the thorax predominantly black; hair 

of T3-5 laterally variable yellowish-white, but 

usually white at least posteriorly in the middle 

of T4.
Phenology Chart

APR MAY JUNE JULY AUG SEPT OCT

Females

Males

94 Bumble Bees of the Eastern United States

Male Bombus fernaldae foraging.

Photo Beatriz Moisset

Fernald cuckoo bumble bee

• Uncommon

• Select food plants: Potentilla (Typical Cinquefoils), Rubus, 

Trifolium (Clovers), Solidago (Goldenrods)

• Hosts: B. perplexus, B. rufocinctus

• Can be confused with B. insularis

Bombus fernaldae
Bumble Bees of the Eastern United States 95

Lateral image of a female Bombus fernaldae.

Photo Sheila Colla

Female Bombus fernaldae face.

Photo Sheila Colla

Bombus fernaldae continued
96 Bumble Bees of the Eastern United States

Bombus fernaldaecontinued
Bumble Bees of the Eastern United States 97

Bombus fernaldae continued

Females (no workers, colors refer to pile or ‘hair’):

• T1 often yellow. Face black, top of the head and 

T4 yellow or cream, T5 black.

• Hind tibia with the outer surface convex and 

densely hairy. Hair of the face black. T6 curled 

very strongly under the metasoma and pointing 

anteriorly, S6 ending distally with a shiny 

triangular spine, the lateral keels small. Hair 

long and uneven.
98 Bumble Bees of the Eastern United States

1 Pollen baskets present (social species) ... 2

- Pollen baskets absent (parasitic species) ... 26

2 (1) T1–T4 pile dorsally completely yellow or brown ... 3

- T1–T4 pile dorsally not completely yellow or brown ... 4

3 (2) Face pile predominantly black; thorax sides with the pile 

predominantly yellow ... fervidus

- Face pile predominantly yellow; thorax sides with the pile 

predominantly black ... borealis

4 (2) T2–T3 pile completely yellow, or yellow except T2 with a 

small amount of black anteriorly in the middle ... 5

- T2–T3 pile with extensive black, orange, or red ... 8

5 (4) Cheeks as long as or shorter than broad (L≤B), head round; 

wings light brown; T5–T6 pile often with a few white, yellow, or 

orange hairs ... 6

- Cheeks longer than broad (L>B), head elongate; wings dark 

brown; T5–T6 pile completely black ... 7

6 (5) Thorax pile with a black band between the wing bases ... 

terricola

- Thorax pile without a black band between the wing bases ... 

perplexus

7 (5) Top of the head between the ocelli with the pile entirely 

black; T1 pile yellow or black but often with some yellow, 

Identification Key

for the female bumble bees 

of the Eastern United States 

The following dichotomous key 

designed by Paul Williams will help 

you identify female bumble bee 

specimens to species. Starting at the 

first set of statements, determine which 

characteristics your specimen has 

and move to the next appropriate set 

(numbered at the end of the statement). 
Bumble Bees of the Eastern United States 99

especially in the middle; ocelli located in front of the 

supraorbital line by less than one ocellar diameter ... 

pensylvanicus

- Top of the head between the ocelli with the pile with 

some yellow hairs; T1 pile black but often with some 

yellow, especially at the sides, fewer yellow hairs in 

the middle; ocelli located in front of the supraorbital 

line by more than one ocellar diameter ... auricomus

8 (4) T3 pile predominantly orange-red, at least away 

from the midline ... 9

- T3 pile predominatly black, yellow, or pale orange ... 

10

9 (8) Cheeks as long as broad (L=B); T2 pile 

predominatly orange-red, often with some black in the 

middle ... ternarius

- Cheeks shorter than broad (L<B); T2 pile often 

yellow, at least anteriorly in the middle ... rufocinctus

10 (8) T3–T4 pile entirely black ... 11

- T3–T4 pile with yellow, brown, orange, or red ... 24

11 (10) T2 pile completely black ... impatiens

- T2 pile with yellow or brown, at least with a few pale 

hairs anteriorly in the middle ... 12

12 (11) T2 pile brown in the middle and darker than T1 

... 13

- T2 pile yellow or brown in the middle but similar to 

T1 ... 14

13 (12) T2 pile black on the posterior corners ... 

griseocollis

- T2 pile yellow on the posterior corners ... affinis

14 (12) Sides of the thorax with the pile extensively 

black ... perplexus

- Sides of the thorax with the pile almost completely 

yellow ... 15

15 (14) T2 pile not completely yellow dorsally as far as 

the posterior edge, a patch of entirely black hairs at 

least on the posterior dorsal corners ... 16

- T2 pile yellow dorsally as far as the posterior edge, 

sometimes with a few black hairs but only below 

where T2 curves ventrally at the sides ... 19

16 (15) Top of the head between ocelli with the pile 

black, at most with a few yellow hairs intermixed ... 

griseocollis

- Top of the head between ocelli with a patch of pile 

predominantly yellow ... 17
100 Bumble Bees of the Eastern United States

17 (16) Cheeks longer than broad (L>B), head elongate; 

T4–T5 pile completely black ... 18

- Cheeks shorter than broad (L<B), head round; T4–

T5 pile with or without yellow ... rufocinctus

18 (17) T2 pile anteriorly at the sides entirely black; face 

pile rarely with yellow ... bimaculatus

- T2 pile anteriorly at the sides yellow; face pile 

usually with some yellow intermixed ... vagans

19 (15) Wings light brown; cheeks nearly as long as 

broad or longer (L<B, L>B); T2–T4 pile medium to 

long and erect ... 20

- Wings dark brown; cheeks very short (L«B), about 

half as long as broad; T2–T4 pile very short, even, 

and decumbent ... fraternus

20 (19) Hind basitarsus with the posterior edge nearly 

straight in the distal three quarters; top of the head 

between the ocelli with the pile usually predominantly 

yellow; body size small to medium (length ≤ 19mm) 

... 21

- Hind basitarsus with the posterior edge evenly 

arched in the distal three quarters; top of the head 

between the ocelli with the pile black with only a 

few yellow hairs intermixed; body size usually large 

(length ≥20 mm) but includes occasional smaller 

individuals ... affinis

21 (20) Cheeks shorter than or equal to broad (L≤B), 

head round ... 22

- Cheeks longer than broad (L>B), head elongate ... 

23

22 (21) Cheeks shorter than broad (L<B); ocelli located 

slightly in front of the supraorbital line ... rufocinctus

- Cheeks as long as broad (L=B); ocelli located on the 

supraorbital line ... sandersoni

23 (21) Thorax pile with many black hairs between the 

wing bases; face pile with few or no yellow hairs; T3 

pile black ... vagans

- Thorax pile with few or no black hairs between 

the wing bases; face pile varying from black to 

having many yellow hairs; T3 pile black or yellow ... 

perplexus

24 (10) Cheeks shorter than broad (L<B); ocelli located 

slightly in front of the supraorbital line ... rufocinctus

- Cheeks as long as broad (L=B); ocelli located on the 

supraorbital line ... 25
Bumble Bees of the Eastern United States 101

25 (24) T3 pile at least anteriorly partly yellow or brown; 

T4 pile often all black, or with some yellow or white 

hairs, but never orange ... perplexus

- T3 pile predominantly black; T4 pile entirely or at 

least posteriorly orange ... frigidus

26 (1) T2–T5 pile medium to long and strongly 

overlapping, at least partly obscuring the surface; 

T1–T6 pile either with yellow, or if entirely black then 

the sides of thorax with the pile entirely yellow; wings 

light or medium brown; between the wing bases the 

pile with or without a black band or spot ... 27

- T2–T5 pile very short, scarcely overlapping, 

and inconspicuous, the surface very glossy and 

unobscured, appearing bare; T1–T6 pile entirely 

black; sides of the thorax with the pile predominantly 

black; wings dark brown; between the wing bases the 

pile always with a black band or spot ... variabilis

27 (26) Top of the head between the ocelli with 

predominantly yellow pile; sides of the thorax with the 

pile predominantly yellow; T4 pile black and/or yellow 

or white ... 28

- Top of the head between the ocelli with black pile, 

at most with a few yellow hairs; sides of the thorax 

with the pile predominantly black; T4 pile completely 

pale, usually nearly white medially ... ashtoni

28 (27) T4 pile black; between wing the bases the pile 

without a black band, but sometimes with a black 

spot ... citrinus

- T4 pile with some yellow or white laterally; between 

the wing bases the pile with a black band present or 

sometimes with a black spot ... 29

29 (28) Face pile black; T1 pile with yellow hairs 

laterally; T4 pile predominantly yellow or white; tip of 

the abdomen strongly recurved, pointing anteriorly; 

S6 apex extending beyond T6 as a curved spine ... 

fernaldae

- Face pile with a mixture of yellow and black hairs; 

T1 pile black; T4 pile predominantly black with yellow 

laterally; tip of the abdomen weakly recurved, pointing 

ventrally; S6 and T6 equal in length ... insularis
102 Bumble Bees of the Eastern United States

Acknowledgements

We gratefully acknowledge help and valuable discussion 

from John Ascher, Laurie Davies Adams, Steve 

Buchmann, Cory Sheffield, Laurence Packer, Claudia 

Ratti, Fawziah Gadallah, James Strange, Chris Plowright, 

Liz Day, Elizabeth Sellers, Sam Droege, Laura Burkle, 

attendees of the 2009 Bombus Experts Meeting in 

Washington, DC, and photograph providers.

Additionally, we would like to thank the following for use 

of data for producing range maps:

Caroline Scully, Antioch University New England; John 

Ascher, American Museum of Natural History; 

Ohio State University Hymenoptera Online Database; 

Illinois Natural History Survey; Yale University, Peabody 

Museum; University of Connecticut Insect Collections; 

University of Vermont’s Zadock Thompson Zoology 

Collection; Canadian National Collection of Insects; 

Rachael Winfree, Rutgers University; Sam Droege, U.S. 

Geological Survey, Patuxent Wildlife Research Center; 

Michael Arduser, Missouri Department of Conservation; 

Kevin Matteson, Fordham University; Kurt Pickett, 

University of Vermont; Helen Young, Middlebury College; 

Ross Bell, University of Vermont; Jeff Freeman, Castleton 

State College; Don Miller, Lyndon State College; Trish 

Hanson, Vermont Department of Forests and Parks; 

Vermont Fish and Wildlife Department.

Funding for this project was provided by the Pollinator 

Partnership, the U.S. Department of Agriculture Forest 

Service, and the National Fish and Wildlife Foundation. 

Funding for the high definition camera was provided by 

CFI and ORF.
Bumble Bees of the Eastern United States 103

Web and Other Resources

Colour Key to the Bombus of the World by Paul Williams [Online]

http://www.nhm.ac.uk/research-curation/research/projects/bombus/_key_colour_world/worldcolourkey.html

Bumble bee Economics by B. Heinrich, Harvard University Press, 2004.

Bumble bees by D.V. Alford, Davis-Poynter, London, 1974.

Bumble bees: their behaviour and ecology by D. Goulson, Oxford University Press, 2003.

Bumble bee vulnerability and conservation world-wide. Apidologie 40: 367-387. Williams, P.H. & J.L. Osborne. 

2009. [Online]

http://www.nhm.ac.uk/research-curation/research/projects/bombus/Williams&Osborne09_review.pdf

Pollinator Partnership www.pollinator.org for Bombus White Paper

Xerces Society of Invertebrate Conservation [Online]

http://www.xerces.org/bumble bees/

Discover Life Bumblebee Key [Online] 

http://www.discoverlife.org/mp/20q?guide=v bees
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FS-972

March 2011