Pollinators 101: Everything You Need to Know
Quick Key Facts
- It is estimated that 200,000 to 300,000 species of invertebrates — like bees, beetles, butterflies, moths and mosquitoes — serve as pollinators worldwide.
- Around 2,000 mammals, birds, reptiles and other species of vertebrates — like lizards, bats, honey possums, squirrels, shrews, mice, lemurs, flying foxes and marsupials — also serve as pollinators.
- Of the leading food crops, about 75 percent — 87 of 115 — depend on pollinators.
- Bats pollinate about 528 species of plants.
- More than 80 percent of plant species are dependent on pollinators.
- At least 30 percent of 1,500 crop species worldwide depend on pollinators.
- More than 150 food crops — like blueberries, apples, almonds, pears, cranberries, plums and squash — are reliant on pollinators in the U.S.
- A single female southeastern blueberry bee pollinates around 50,000 blueberry flowers that produce more than 6,000 salable blueberries at a value of about $75.
- A single watermelon flower requires as much as 1,000 grains of pollen in a matter of a few hours to be able to produce fruit that is marketable.
- In the U.S., the number of managed honey bee colonies was around six million in 1947, four million in 1970, three million in 1990, 2.5 million in 2014 and there were an estimated 2.71 million in 2020.
What Are ‘Pollinators’?
A pollinator transports pollen from the stamen (male part) of the flower of a plant to the stigma (female part) of the original or another flower. Moving the pollen is necessary to fertilize the plant so that it can produce fruit, seeds and new plants. While the pollen of some plants gets carried by water or the wind, many plants that are not self-pollinating rely on insects and animals to transport their pollen.
Pollinators visit flowers searching for food, materials to build nests, shelter and mates. Many species of bees purposefully collect pollen and nectar for energy, nutrients and protein. The nectar is produced by the glands of flowers as a reward for hard-working pollinators. Other species, like bats, birds and rodents, carry pollen unintentionally after it sticks to their bodies while they are feeding on nectar or otherwise coming in contact with a flower.
Why Are Pollinators Important?
Worldwide Food Crops
Without pollinators, we wouldn’t have one out of every three bites of food we eat. That’s because about 35 percent of the world’s food crops depend on animal pollinators to produce the fruits, nuts, vegetables, seeds and even coffee we love.
More than 3,500 native bee species ensure crop yields, but there are many more pollinators out there. It is estimated that more than 200,000 species help pollinate the plants that make up the world’s crops.
Pollinators play a key role in the health of our planet’s ecosystems. In fact, none of them could survive without pollinators. More than 80 percent of all flowering plants on Earth are pollinated by insects and other animal pollinators. That includes 180,000 plant species and around 1,400 food crops.
Plants are dependent on pollinators, and all organisms on Earth are dependent on plants. Plants provide oxygen, clean the air and stabilize the soil, which prevents too much runoff, controls flooding and protects the health of our waterways. Plants also provide food and shelter for wildlife.
Types of Pollinators
Without a doubt, bees are the most important pollinators. We share our planet with at least two trillion bees, consisting of about 20,000 species. There are 81 million honey bee colonies and 100 million managed beehives. Each beehive contains about 10,000 to 60,000 bees.
Where there are flowers, there are bees, and that goes for almost everywhere on the planet, except Antarctica. There are no flowering plants on the entire continent, and it’s also too cold for our pollinating friends. Temperate and arid regions are hotspots for bees.
Honey bees are responsible for pollinating most of the flowering plants on Earth, which include more than 130 kinds of vegetables and fruits. The average honey bee has the ability to visit more than 2,000 flowers in a single day.
Bees can live communally in hives or by themselves. In a hive, female drone or worker bees collect pollen and nectar and bring it back for food and to make honey. The more than 200 species of solitary bees don’t produce honey, but they may pollinate flowers.
Wasps and bees are close relatives — both are in the same order as ants. While bees are the biggest pollinators on the planet, wasps are also useful pollinators. In appearance, wasps are leaner, their legs are longer and they generally lack the distinctive “fuzz” of bees. The absence of fuzzy hairs for the pollen to cling to as they move from flower to flower means wasps are less effective as pollinators. The tongues of most wasps are short, so they seek out shallow blooms.
Both wasps and bees have social and solitary species and, as with bees, social wasps are usually the most active pollinators. Wasps may get a bad rap because of their potential to sting, but they are extremely beneficial to ecosystems, as well as to the health of your garden.
Tiny fig wasps — found in abundance in tropical climates — are specialized species responsible for pollinating about 900 species of fig. Figs’ flowers are found on the inside of the immature fruit, and when the flowers are ready to be pollinated the fig releases a tantalizing aroma that attracts the specific species of female wasp that is matched to that particular type of fig. The female fig wasp bores her way inside the fig through the small opening at the end of the fruit, losing pieces of her antennae and her wings in the process. She then visits the flowers on the inside of the fruit, pollinating them and laying her eggs inside its future seeds, which will nourish her larvae once they are born. The wasp then dies inside of the fig.
Birds are important pollinators. There are 2,000 bird species worldwide who feed on the nectar, spiders and insects of flowers. More than 60 flower families are pollinated by birds in a process called ornithophily.
In the continental U.S., hummingbirds are the primary wildflower pollinator, while in Hawaii it’s honeycreepers. Sunbirds do much of the pollinating in the tropics of Africa, Asia and Europe, while brush-tongued parrots are productive pollinators in New Guinea. Honeyeaters are the star pollinators of Australia, but lorikeets are also important pollinators Down Under.
Birds usually feed on flowers that have curved petals, funnels, tubes or cups and are bright orange, yellow or red. They visit flowers that are open during daylight hours and have strong places to perch. Hummingbirds feed while hovering but use perches to rest, preen or guard a nearby feeder. Birds do not have a keen sense of smell, so the flowers they visit are typically odorless. Flower pollen is typically large and sticky so that it can leave a dusting on the beak, neck, back and feathers of the birds as they forage for nectar, which is hidden deep down in some flowers.
All of the more than 300 hummingbird species in the world are found in the western hemisphere, from southeastern Alaska to the southern tip of Chile. The further south you go, the more hummingbird species you’ll find. The only species of hummingbird in the Eastern U.S. is the ruby-throated hummingbird, while there are a dozen species in the Southwest.
Planting native nectar-producing plants is the best way to support hummingbirds and other pollinators. Hummingbird feeders filled with a mixture of purified water and 20 to 30 percent sugar — just refined white sugar, no alternatives like artificial sweeteners, brown sugar or honey — are a way to support the migrating and resident populations of these tiny birds.
While birds aren’t known as food crop pollinators, many flower species would die out if not for their feathered pollen couriers.
For about 200 million years, beetles have been important pollinators. They were one of the first insect pollinators of flowers and are essential for ancient species like spice bush — a shrub in the laurel family that is native to North America — and magnolias, which are native to North and South America, East Asia and the Himalayas.
Research has determined that beetles can see colors, and they are typically attracted to flowers that are green, white or dull white. They usually visit flowers that have a strong, fruity smell, are open during daylight hours, are bowl-shaped and produce a moderate amount of nectar.
As beetles move from flower to flower, grains of pollen stick to their bodies. They munch through petals and other parts of large, single flowers or small flower clusters like goldenrods — most species of which can be found in the meadows, stream banks, prairies, plains, pastures and savannas of the U.S. and Canada.
Although they don’t seek out pollen directly like the super pollinating bees do, ladybugs are important, if accidental, pollinators. In addition to being pollinators, these beautiful and colorful insects — a group of ladybugs is called a “loveliness” — are considered beneficial because they keep down populations of insects that feed on plants.
There are about 5,000 ladybug species all over the world, including around 500 species in the U.S. They sport a range of colors — red, black, orange, pink, grey and brown. Ladybugs can be found roaming in forests, open meadows, fields and gardens, as well as in patches of weeds in vacant lots and along roadsides in search of shelter and food. When it’s cold out, many of them migrate indoors, and you may find some snuggled in a nook or crevice of your home.
While ladybugs don’t seek out pollen, pollen grains — each one containing two male reproductive cells of a plant — stick to their bodies, undercarriages and legs as they search for prey. Ladybugs have a voracious appetite and are able to eat as many as 75 aphids per day. While hunting is their main reason for being on a flower, ladybugs do occasionally supplement their diet with nectar.
Ladybugs are attracted to blooms that are yellow and white with flat leaves that make comfortable landing pads. They visit many types of plants, including beans, chives, cilantro, dill, feverfew, gardenia, honeydew, marigolds, orchids, peas, roses, sunflowers and tomatoes.
There are more than 1,400 bat species on Earth, and they can be found in most parts of the world, save for polar and extreme desert regions. The smallest bat, which is also the smallest mammal in the world, is the Kitti’s hog-nosed bat — also known as the Bumblebee Bat — which weighs less than a penny. Flying foxes are the largest of the bat species with a wingspan as wide as six feet.
Bats are important pollinators and most do their work pollinating crops and spreading seeds at night. They feed on the pollen and nectar of plants like dates, dragon fruit, figs, peaches, African locust beans, durian and mangoes, the flowers of which are only open after dark. Bats enjoy these plants’ mildly scented pale or white flowers.
Not all bats are pollinators, but the ones that are have fewer and smaller teeth, as well as long tongues and snouts, which help them collect nectar efficiently. As an example, Mexican long-nosed bats can visit as many as 30 flowers a night. When bats feed, pollen covers their faces and dusts their bodies, which transport it to the next flower.
Butterflies are less efficient pollinators than bees because their long, thin legs keep them above the pollen so they don’t pick up much of it with their bodies. They feed during the day on nectar from clusters of wildflowers and prefer those that are flat and easy to land and perch on. They favor flowers that are brightly colored red, orange, yellow, purple and pink, but don’t have a good sense of smell.
Some of butterflies’ favorite blooms are lavender, swamp milkweed, oregano, fennel, black-eyed Susan, heliotrope, aster, Liatria — also known as blazing star flowers — pot marigolds, salvia, bee balm, lantana and sunflowers.
Worldwide, there are more than 140,000 species of moths and butterflies. Like bats, many moths, but not all, are nocturnal and active at night. They visit flowers that open in the late afternoon or at night by either landing on or hovering over them.
Flowers visited by moths usually grow in clusters and are white or pale in color. The flowers they visit — like gardenia, tobacco, yucca and morning glory — usually have “platforms” for them to land on and plentiful, deeply hidden nectar.
The yucca plant is another species that relies on a specific type of insect for its survival: the yucca moth. The female yucca moth gathers pollen and forms it into a ball, then “stuffs” it into the hole of the stigma of the flowers of the yucca plants she visits. If it wasn’t for this species of moth, the yucca flower wouldn’t develop into its fruit or seed pod. The female yucca moth lays an egg in one or more of the six chambers of the yucca flower’s base, which protects the egg until it hatches.
Not as well known as pollinators as bees or hummingbirds, flies are extremely important pollinators of plants and crops. One study involving 105 crops found that flies visited 72 percent and bees 93 percent. Because they’re frequently active when it’s cooler outside, flies can sometimes even outpollinate bees in early spring.
Adult flies feed on the pollen and nectar of flowers but don’t collect it like bees do. As with other pollinators, pollen gets stuck to the fly’s body and is transported to other flowers.
One species of fly — the syrphid, also known as the “hover fly” or “flower fly” — has been known to visit more than 50 different types of crops. One of the most common pollinating flies, syrphid flies have black and yellow striped bodies, so they can look a lot like bees. In the northeastern U.S. there are more than 400 flower fly species and more than 6,000 worldwide. Many flower fly species feed on insects and thus provide natural pest control.
To attract flies to your garden, plant a variety of plant species and include hover and tachinid fly favorites from the Asteraceae (daisy), Rosaceae (rose), and Apiaceae or Umbelliferae (umbellifers, which include celery, carrot or parsley) families. Flies generally have a preference for white flowers that have an open structure, but these flowers aren’t floral so much as dank or earthy smelling.
There are many flightless vertebrate mammals that are pollinators, including mice, squirrels and possums. Some of these pollinators have a symbiotic relationship with particular plants. When the pollinators aren’t able to access the plants that depend on them, their seed and fruit production can decrease significantly.
Non-flying mammals visit at least 85 species of plants across the globe, and the biggest of these pollinators may be the beautiful ruffed lemur. After these natives of Madagascar eat the nectar inside the flowers of the traveler’s tree — which provides a good portion of their calories — their fur is dusted with pollen.
Lizards, skinks and geckos can also be pollinators, particularly on islands.
Several types of rare flowers rely on the blue-tailed day gecko to pollinate them. One, the Trochetia tree, is only found east of Madagascar in the Mascarene Islands.
Benefits of Pollinators
Provide Food for Humans & Wildlife
In terms of monetary value, the one in three bites we eat that was made possible by pollinators equals about $235 to $577 billion in annual worldwide agricultural production, with honey bees responsible for as much as $20 billion of that amount.
Some crops — like almonds, avocados, cantaloupes, pumpkins, cucumbers, eggplants, squash, watermelons and blueberries — would be almost decimated if it weren’t for honey bees. The cacao plant relies on the tiny midge fly to pollinate its flowers on farms in Africa, South America and Australia so that they can be fermented and ground up to make chocolate — a multibillion dollar industry.
Our dependence on pollinators is only increasing, with crops that are dependent on pollinators having increased three times over the past fifty years.
Support Healthy Ecosystems
Pollinators are the cornerstones of Earth’s plant life, which is the basis of its ecosystems. A thriving ecosystem is made up of healthy plant life and the animals that feed upon it. The plants in turn provide food and habitat, clean the air and keep soils healthy and stable, which improves crop productivity, prevents erosion, keeps waters clean and helps mitigate flooding. Flowering plants make up nearly all of the vegetation on our planet and provide an important food source for many animals. Biodiversity literally depends on pollinators.
Provide Raw Materials
Since most flowering plants can’t survive without pollinators, plants and pollinators together provide many of the raw materials we rely on — like cotton, biofuels and wood — as well as medicines and half the planet’s oils.
Help Combat Climate Change
Ninety percent of all plants on Earth have flowers and more than 80 percent of those rely on pollinators to reproduce. Most of the air we breathe comes from marine plants — 70 percent — but plants that grow in soil also provide much of our oxygen and absorb carbon dioxide, which helps combat climate change. Plants also help mitigate climate change by sequestering carbon through photosynthesis and storing it in the soil.
About 10 percent of the moisture in Earth’s atmosphere comes from plants, and without their transpiration process, the world’s ecosystems would also experience less rain, which would exacerbate the effects of climate change.
Challenges to Pollinators
Pollinator populations are shrinking worldwide due to several overlapping factors, including pesticide use, the spread of viruses, bacteria and fungi, destruction and fragmentation of habitat, loss of native plants that provide pollen and nectar, invasive plants and bees, low genetic diversity, pathogens spread by commercially managed bees and climate change.
Since 2006, beekeepers in the U.S. have lost around 30 percent of their colonies each year. Sometimes, total yearly losses can be as high as 42 percent.
One of the biggest threats to pollinators is pesticides. Insecticides, herbicides and fungicides cause multiple layers of harm to pollinators by killing the flowering plants they rely upon for nutrition, affecting pollinators’ memories, navigation and reproduction and, of course, killing the pollinators themselves.
Research has shown that one particular class of pesticide — neonicotinoids, which are sprayed on soil or coated on seeds — impairs memory and learning in honey bees and solitary bees. The chemicals in this type of pesticide can also interfere with bees’ reproduction.
Pesticide exposure and not enough nutrients can also make bees more at risk for viruses and parasites.
Honey bees are susceptible to about 20 known viruses, many of which are widespread. Colony collapse is associated with several of these. Added stressors — such as the presence of varroa mites, which suppress the immune system of their host bee and spread viruses themselves — can affect how deadly these viral infections can be. Many honey bee viruses also infect other bee species.
A major concern is that some viruses can be spread from managed bee colonies to populations of native bees.
Two particular types of bacteria cause outbreaks of American foulbrood and European foulbrood in honey bees. Both of these pathogens can destroy whole colonies, and American foulbrood can cause entire apiaries to be demolished.
Only a few bacterial pathogens have been documented in native bee populations, but there are likely many more.
Bee nests, which tend to be warm and humid, are places where fungi can flourish.
One fungal pathogen, chalkbrood, affects honey bee larvae. An infection from chalkbrood doesn’t usually destroy an entire colony, but it can make the colony more easily affected by other stressors or reduce the productivity of the hive. Some solitary bee species — like leafcutting and mason bees — are also at risk of chalkbrood infection from related species of fungi. These bees pollinate certain crops like alfalfa, as well as orchards. It isn’t well known how much chalkbrood affects wild bees, or if commercially managed bee populations encourage the passing of chalkbrood to wild bee populations.
Microsporidia are a type of fungal parasite that affects bee species all over the world. In European honey bees, it causes intestinal infections. One type of microsporidia, Nosema ceranae, can infect multiple generations of North American native bees and many other types of bees, including four honey bee species.
Loss and Fragmentation of Habitat
Pollinators are dependent upon their habitat for nesting sites as well as native plants that provide pollen and nectar, so when their natural surroundings are reduced or decimated by human activities, development, agriculture or climate change, these pollinators lose their homes.
Smaller fragments of habitat like inner city gardens tend to have fewer flowers and places for pollinators to nest than larger areas like natural meadows of wildflowers. Smaller swaths of habitat mean smaller populations of pollinators that are more affected by environmental stressors like disease and drought. Smaller fragments that are connected to larger habitats create a network with more resources for pollinators.
Unique environments can develop in the space where two distinct habitats meet, and these “edge effects” can benefit or harm the pollinators who settle there. The shady edge of a field next to a forest might have flowering plants that can support pollinators, but the edge of a field next to a plot of agricultural land could be saturated with pesticides that could cause them harm.
Global warming magnifies the negatives of habitat loss and fragmentation. Increasing temperatures can shift habitable range for pollinators, while rapidly changing weather patterns can degrade habitat.
Invasive plant species alter the structure and composition of plant communities, as well as the suitability of the habitats they invade. How bees respond to invasive species can vary greatly. For instance, invasive plants can affect the abundance or diversity of native plants, and some bees aren’t able to forage on certain plants. This can be due to the structure of a plant’s flowers, the plant not providing enough nutrients or being toxic, the bee not recognizing the plant species or other factors.
It is possible for an invasive plant species to become part of a bee’s diet if, for example, it is compatible with the bee’s digestion and its nutritional benefits outweigh the foraging costs to the bee.
Low Genetic Diversity
According to recent studies, the genetic diversity of some European honey bees has decreased significantly within their native range in the last half of the 20th century, with some wild and managed populations coexisting.
The genetic diversity of wild and managed populations is threatened by beekeeping practices like breeding programs, moving hive stock on larger scales, trading queens and introducing populations to new areas. Lower genetic diversity can occur within a few decades and can contribute to population decline.
Scientists have found that declining populations of North American bumblebees are associated with significantly lower genetic diversity and much higher incidence of being infected with the pathogen Nosema bombi. Fragmented habitats can result in smaller populations and reduced gene flow, which can also lead to lower genetic diversity.
As global warming causes the mercury to rise and flowers bloom earlier than usual, pollinators of all kinds may miss out if they arrive after particular flowers they rely upon have completed their life cycles. This not only means pollinators go without food, it also means fewer plants get pollinated.
Rising temperatures could be a factor in bumblebee decline. The number of North American bumblebees has declined by half since 1974, mostly in areas with the highest temperature increases.
Additional effects of climate change like flooding, the spread of invasive species and shorter fire cycles can threaten native habitats of pollinators.
What Can We Do to Support Pollinators?
As a Society?
There are many things we can do as a society to help pollinators thrive. Reporting sightings of pollinators and collecting data for citizen science projects can help scientists better protect and support pollinators.
We can help with the restoration of pollinator habitat by volunteering with conservation organizations that use best management practices. And we can let our state and local representatives know that we support pollinators, and that the restoration and preservation of pollinator habitat is crucial.
Educating ourselves by visiting a botanical garden, local Audubon Society, local wildlife refuge, beekeepers in our area or taking a class to learn about native plants means we’ll be better equipped to make informed decisions, take action and share our knowledge about pollinators and their habitats with others.
In Our Own Lives?
One of the best things we can do for pollinators is to create habitat by planting a garden where flowering plants they are attracted to can flourish. When planting for pollinators, choose plants that are native to your area.
Planting in clusters can help pollinators locate flowers, and planting so that you have consistent blooms throughout the growing season helps ensure pollinators have enough nectar from spring through fall.
Fallen branches, leaves and twigs, logs and plant stems can be used as nesting sites for ground and cavity-nesting bees, so leave them on the ground in an area where no one can trip on them. You can also use wood nesting blocks to provide a place for wood-nesting natives. A patch of well-drained bare earth can be used for ground-nesting bees. Ground-nesting bees love south-facing areas where they can get the most sun.
Building a bat house can help bats survive by giving them a safe place to give birth and care for their young.
Installing or planting a windbreak like a fence or a hedgerow can help make it easier for pollinators to fly around and visit the flowers in your garden. It can also help protect pollinators from drifting pesticides.
Pollinators need to stay hydrated, so leaving a shallow dish of water with several partially submerged stones on your back porch, a tree stump or a windowsill can provide a safe place for pollinators to land and get a drink without risking drowning.
Hummingbirds use materials from plants like lichen and mosses to build their nests in shrubs and trees and have even been known to use spider webs as nest-building material. Leaving these materials intact in your garden is helpful to these smallest of vertebrate pollinators.
Other ways to support pollinators include avoiding pesticide use and buying local honey to support local bees and beekeepers — or becoming a beekeeper yourself!
Buying organic food, beverages, textiles and products like cosmetics and body care supports local farmers who use regenerative farming practices and fewer pesticides that support pollinator health.
With all pollinators do for the planet, you might say the balance of the world and its ecosystems rests on the wings of a bee, on the dots of a ladybug or on the nose of a bat. Without pollinators, many plant and animal species would struggle to survive, and some would disappear altogether.
The future of our planet as we know it depends on us developing a harmonious relationship with pollinators. We can support our pollinating friends by leaving a pile of leaves undisturbed, building a bat box or planting a field of wildflowers — because a world without pollinators would be a much less diverse and colorful place.