The Lives of Bees
Page 3
scutellata) and the Arabian peninsula ( A. m. yemenitica).
and Oman) and eastern Africa (e.g., Sudan, Somalia, and Chad). This slight
introgression of African genes into the modern population of wild colonies
living in the forests near Ithaca, New York, is probably a result of African-
ized honey bees—hybrids of African and European races of Apis mellifera—
becoming established in parts of the southern United States in the late
1980s and early 1990s. These southern regions—which include the states
of Florida, Georgia, Alabama, and Texas—have warm climates favorable
to Africanized honey bees, and they are where much of the commercial
queen production in the United States takes place. Evidently, for the last
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12 Chapter 1
25 or so years, queen producers in the southern states have been shipping
queens carrying some genes of African descent to beekeepers in the north-
ern states. Migratory beekeepers who keep their colonies in Florida over
winter and then truck them north in spring to pollinate apples, cranber-
ries, and other crops, have probably also contributed to the northward
trickle of genes of the Africanized honey bees.
This new, high- tech look at the genes of the honey bees living in the
woodlands south of Ithaca has revealed two important things. First, it has
shown us that the arrivals of African honey bees in Florida and Texas in the
1980s and 1990s have affected only very slightly the genetic composition
of the wild colonies living in the forests near Ithaca. In other words, the
genetic makeup of these wild colonies still reflects mainly the nearly 400-
year history of imports of honey bees from Europe. Second, it shows that
the genes in this population of wild colonies have come predominantly
from honey bees native to southern Europe, even though the introductions
of honey bees from northern Europe started some 200 years earlier. Pre-
sumably, this reflects the greater popularity among beekeepers of bees
from Italy and Slovenia ( A. m. ligustica and A. m. carnica), in southern Eu-
rope, relative to the dark European honey bees ( A. m. mellifera) from vari-
ous places in northern Europe. Most beekeepers prefer bees that are calm
and produce much honey, and the lighter- colored bees of southern Eu-
rope, compared to the darker- colored bees of northern Europe, tend to
be less likely to run around when a hive is opened and more likely to build
up large populations of worker bees and amass large stores of honey.
Given that most of the genes in the wild colonies living near Ithaca are
from honey bees adapted to the relatively mild climates of southern Eu-
rope, and given that Ithaca winters are long, snowy (Fig. 1.5), and often
bitterly cold (lowest temperatures about −23°C/−10°F), we need to ask:
Are the wild honey bees living near the Ithaca area well adapted for life in
this northern region of North America? We will see in the coming chapters
that the answer to this question is a solid yes; multiple studies have found
that the wild colonies of honey bees living in this region are impressively
skilled at living here. These studies have looked at how the colonies’ nest-
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Introduction 13
Fig. 1.5. Winter look of an apiary located in Ellis Hollow, near Ithaca, New York.
site preferences, seasonal patterns of brood rearing and swarming, forag-
ing skills, overwintering abilities, and defenses against pathogens and para-
sites are all highly adaptive for life in this northeastern corner of the
United States. Perhaps the most compelling indication that these wild
colonies are well adapted to their current environment is that they possess
a powerful set of behavioral defenses against the aptly named ectoparasitic
mite Varroa destructor. In chapter 10, we will see how the population of
wild colonies living near Ithaca was decimated when this mite—whose
original host is an Asian honey bee species, Apis cerana—reached the Ithaca
area in the mid- 1990s but then recovered through strong selection for
multiple defensive behaviors in worker bees that kill these mites. Indeed,
we now know that the density of wild colonies of honey bees in the 2010s
(ca. 20 years post- Varroa arrival) matches what it was in the 1970s (ca. 20
years pre- Varroa arrival).
We should not be surprised that the wild colonies of honey bees living
in the forests around Ithaca are well adapted to survive and reproduce in
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14 Chapter 1
these northern woodlands, where the winters are far longer and colder
than the winters in many of the bees’ ancestral homelands in Europe. After
all, these colonies have been exposed to strong natural selection to adapt
to the climate throughout their nearly 400- year history of living in the
northeastern United States, and there are countless studies by biologists
that demonstrate that evolution by natural selection can produce a popu-
lation of plants or animals with a robust solution to a new problem in just
a few years. Besides the rapid evolution of Varroa resistance in the wild
colonies of honey bees living in the forests around Ithaca, there is the
example of the Africanized honey bees ( Apis mellifera scutellata) in Puerto
Rico evolving docility in only 10 or so years. Evidently, this rapid evolu-
tionary change, which occurred between 1994 and 2006, was driven by
natural selection favoring genes for reduced aggression in honey bees
living where there are no major predators. Another striking example of
an insect’s rapid behavioral adaptation to a changed circumstance is the
adaptive disappearance between the late 1990s and 2003 of the calling
song of male field crickets ( Teleogryllus oceanicus) on the Hawaiian island
of Kauai. This behavioral change followed the accidental introduction of
parasitic flies that locate host crickets by orienting to the crickets’ chirps.
Male crickets with mutations for wing structures that silenced their sing-
ing were strongly favored by natural selection. Quick evolution led to
quiet crickets!
ROAD MAP TO WHAT FOLLOWS
This book aims to provide you with a clear view of the natural lives of
honey bee colonies, especially those living in cold climate regions of the
world. To enjoy this view, you will need to work your way through some
new scientific terrain, make dozens of stops along the way, and look care-
fully in a different direction at each stopping place. You will soon see that
this book is partly a synthesis of the work of many research biologists and
partly a travelogue of my personal quest to better understand this special
piece of nature. Here is a road map to what follows.
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Introduction 15
Chapter 2 describes when, where, and how I became intrigued with the
puzzle of how colonies of the “domestic” honey bee, Apis mellifera, live in
the wild. This chapter introduces you to the landscape and forests south of
the small city
of Ithaca, in central New York State, which is where many of
the investigations described in this book were conducted. It also describes
how, in the late 1970s, I began studying the population of wild colonies
living in one of these forests, the Arnot Forest. It further describes how,
in the early 2000s, I was amazed to find wild colonies still living in this
forest even though the deadly ectoparasitic mite Varroa destructor had spread
to the Ithaca area sometime in the early 1990s. This chapter goes on to
review what we know about the abundance (and persistence) of wild colo-
nies of Apis mellifera in other places. By the end of chapter 2, you will see
clearly the two main puzzles that are solved, step- by- step, in the rest of
the book: 1) How are the wild colonies of honey bees living in the woods
around Ithaca able to survive without being treated with miticides? And,
more broadly, 2) How do the lives of wild and managed colonies of honey
bees differ, and what can we learn from these differences to be better
stewards of our most important pollinator?
Chapters 3 and 4 take a step back from the present- day biology of Apis
mellifera to explore why, until recently, we have known so little about the
natural lives of honey bees. We will see that honey bee colonies probably
began living in man- made structures (hives) as soon as humans made the
shift from being mobile hunters and gatherers to living as sedentary herd-
ers and farmers, some 10,000 years ago. It is likely that as soon as we
humans stopped being destructive honey hunters, we began to become
manipulative beekeepers. We will also see how, over thousands of years,
we gradually refined our artificial housing of managed honey bee colonies
to make it easier and easier for us to reach into their homes and steal their
golden honey. Thus, step- by- step, we grew increasingly disconnected from
how honey bees live in the wild. Meanwhile, the bees never yielded their
nature to us and instead continued to follow a way of life set millions of
years ago. It was not until about 70 years ago that we perfected the means—
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16 Chapter 1
artificial insemination of queen bees—to control this insect’s mating and
breed it for our purposes. Fortunately, even today, precious few queens
are artificially inseminated. Most still mate with whatever drones they
encounter.
Chapters 5 through 10 review what has been learned, mostly over the
last 40 years, about the natural history of honey bees living in temperate
regions of the world. Here we will examine the interwoven topics of nest
architecture, annual cycle, colony reproduction, food collection, tempera-
ture control, and colony defense. Throughout these chapters, we will see
how the marvelous inner workings of a honey bee colony have been shaped
by natural selection for life in the wild, not in domestic settings, so honey
bees are still perfectly able to survive and reproduce without a beekeeper’s
supervision. More specifically, we will see how the bees build and use their
beeswax combs, time their swarming and drone rearing, operate a factory-
like organization of food and water collection, maintain thermal homeo-
stasis in their nests, and sustain an arsenal of colony defenses. These are all
parts of a honey bee colony’s complex suite of adaptations for passing on
its genes to the next generation of colonies.
Finally, chapter 11 presents the take- home lessons from what we have
learned about how Apis mellifera lives in its natural world. The chapter first
summarizes the findings reported in the previous chapters in the form of
a 21- point comparison between the lives of colonies living in the wild and
those of colonies managed for apicultural purposes. It then offers 14 prac-
tical suggestions of ways beekeepers can help their bees live closer to their
natural lifestyle and so enjoy less stress and better health.
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2
BEES IN THE FOREST, STILL
Reports of my death have been greatly exaggerated.
—Mark Twain, New York Journal, 1897
Many of the studies that I will describe in this book are ones that my col-
leagues and I have conducted over the past 40 years with the wild colonies
of honey bees that live in the forests near the small city of Ithaca, the home
of Cornell University, in central New York State. Ithaca lies at the southern
end of Cayuga Lake, an elongate, glacially deepened lake that runs north
for nearly 65 kilometers (40 miles). It is one of the 11 Finger Lakes, which
extend south to north across the middle of New York like the fingers on a
pair of outstretched hands (Fig. 2.1). The landscape between these lakes is
one of rolling hills with deep, rich soils lying atop a bedrock of limestone.
This is a fertile and productive region with intensive agriculture, including
vineyards, orchards, and dairy farms. But south of these lakes, and thus
south of Ithaca, we find a hilly, wooded landscape whose topography and
soils differ markedly from those to the north. Here we encounter narrow
valleys that snake between rugged hills, some with nearly vertical slopes,
and acidic soils thinly covering bedrocks of shales and sandstones. The
region south of Ithaca is part of the Appalachian Highlands and has eleva-
tions exceeding 610 meters (2,000 feet). Most of it is ill- suited for farm-
ing, but it supports beautiful hardwood forests that provide prime habitat
for wild animals, including black bears, beavers, bobcats, fishers, mink,
porcupines, foxes, and ravens. Also, wild colonies of honey bees.
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18 Chapter 2
Fig. 2.1. Aerial photo of the Finger Lakes region in New York State. Yellow
dot: the city of Ithaca. Yellow square: the Arnot Forest. Scale bar: 32 kilometers
(20 miles).
The climate of the Finger Lakes region resembles that of northern Eu-
rope. Summers are short, hot, and humid, with temperatures rarely ex-
ceeding 32°C (90°F). Winters are long, cold, and snowy. The temperature
often drops to −18°C (0°F) or lower, and the annual snowfall total averages
more than 150 centimeters (5 feet). If a colony of honey bees is to thrive
in this part of the world, it must be able to cope with dramatic changes in
the weather across the seasons.
ECOLOGICAL HISTORY OF THE FORESTS AROUND ITHACA
The earliest inhabitants of the lands around the Finger Lakes were Paleo-
Indian hunters. Carbon dating the charred remains of their campfires has
shown that these seminomadic hunters arrived soon after the last glaciers
disappeared, some 13,000 years ago, and were present here until about
4,000 years ago. These hunter- gatherers were followed by agricultural
Native Americans who lived in villages of bark- covered longhouses and
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Bees in the Forest, Still 19
tended fields in the rich soils of the land between the lakes. They grew
maize, squash, and beans—the famous “three sisters” of Native American
also hunted game (including deer, turkey, and passenger pigeons), fished
for eels and salmon, gathered acorns and berries, and produced ceramic
cooking pots. Their lifestyle lasted intact from approximately 1000 bce to
the early 1600s, when Europeans from France, England, and the Nether-
lands started intruding upon it. By then the Native Americans living in the
Finger Lakes region were called the Iroquois (or Haudenosaunee, “people
of the longhouse”).
After the American Revolutionary War (1775–1783), the state of New
York gained title to all the Iroquois land, except several small reservations,
and in the late 1790s settlers from the states perched along the Atlantic
coast—mainly New York, Pennsylvania, New Jersey, Massachusetts, and
Connecticut—began moving in. The wealthier settlers built their farms
on the gently sloping, verdant lands between the Finger Lakes, where the
Iroquois people had previously cleared large fields, but the poorer folks
settled in the wooded, hilly lands south of Ithaca, where the land was sold
for bargain prices or was rented to tenant farmers. The hill farmers cleared
the virgin forest, grew potatoes, various grains (wheat, oats, and barley),
and fruits (especially apples), and raised sheep for wool. In the 1840s and
1850s, many of the people living on the poorest lands were Irish immi-
grants who had escaped the Great Famine, caused by the potato blight, and
their presence is recorded in the place names found in these hills. For
example, in the Arnot Forest—the rugged, 1,700- hectare (4,200- acre)
forest preserve where I have conducted many of my studies of wild honey
bees—the most prominent hill is called Irish Hill, and the rocky dirt road
that winds up from the village of Cayuta in Pony Hollow to the abandoned
hill farms atop Irish Hill is the McClary Road. The 1860s census records
show that many of the settlers of Irish Hill—including William Hethering-
ton, Abram and Azara Sealy, and Mary Pearson—were born in Ireland. By
the 1870s, however, farmers working the low- grade soils in the hills south
of Ithaca were deserting their farms in rapidly growing numbers, and most
were gone by the 1920s. Consequently, the vast deforestation of these hills