Brainy Bumble Bees

Bumble bee and jewelweed. © Beatriz Moisset

Some of your garden visitors are undeniably clever. Raccoons and squirrels come immediately to mind. But, bumble bees? How could pinheaded insects be capable of any intelligence? Those who study insects tell us that some are capable of remembering things and, even more amazingly, of learning new things and acting accordingly.

The one that gained a reputation as the Einstein of the insect world is the honey bee. Books have been written about its cleverness and the way it communicates with other members of the colony. Some other members of the six legged crowd also show surprising signs of memory and intelligence. Bumble bees, close relatives of honey bees, and also living in colonies composed of a queen and workers, are not far behind them.

If you enjoy spending some time looking at the visitors to your flowers, you may have a chance to see some examples of their braininess.

A tricolored bumble bee, a regular flower visitor
© Beatriz Moisset

Perhaps, one morning you step into your garden, coffee cup in hand, and see a bumble bee on your flowers. The scene looks familiar; you have noticed it several times before. Could it be the very same bumble bee? There is a good chance you are correct. She, and it is usually a she, is good at memorizing the best business locations—the bushes or clusters of plants with abundant flowers and plenty of valuable resources. She is probably guided by a combination of clues to recognize the area: landmarks, the position of the sun, smells, perhaps even the magnetic field of the earth. Thus your friendly garden visitor develops a daily route; and even memorizes the timing of blooming, morning or afternoon to show up right on schedule. Researchers may learn all these things by painting a little dot of color on the back of the bee so they can follow its comings and goings.

Entering a jewelweed © Beatriz Moisset

Another behavior worth watching is their routine when visiting a flower. I love to see them going inside a jewelweed and am always amazed at the speed with which they proceed. I wish they were a little slower and allowed me to take a few pictures. Learning how to deal with complicated flowers takes practice. A naïve bumble bee may refine her technique with time and the more complicated the flower, the more practice is required.

Bumble bee visiting a turtlehead © Beatriz Moisset

Researchers resort to interesting methods to unravel the mysteries of bumble bee behavior. For instance, they glue little tags of different colors to their backs so they can track down the activities of each individual. They test their ability to recognize flowers by offering them artificial flowers of different colors or different aromas; and filling only certain ones with nectar. The student bees learn to choose the flower of the right color or scent and bypass all others.

Enjoy your garden pollinators next season and see if you can recognize these behaviors and perhaps observe new ones.

More on Bumble Bees:

The Telegraph. Might of the bumblebee.Learning tests, yellow flowers vs. blue 

Bumble Bees, Panda Bears of the InsectWorld 

Spurs: Hard to Get Nectar

Violet.

© Beatriz Moisset

 Many flowers are very particular about their clientele. They have developed ways to make themselves attractive to certain flower visitors while discouraging others. They do so by adopting a certain shape. The spurs of many flowers serve this purpose. A petal or a sepal develops an elongated hollow spike. This is what botanists call a spur.

Violet (Viola mirabilis). Note the spur

Wikicommons. © Antti Bilund

Violets have a spur. Nectar is collected at its bottom. A pollinator needs a tongue long enough to reach the hidden nectar waiting in this special vessel. The rest of the flower is so designed that the insect gets covered with pollen while performing this task. If it is carrying pollen from a previous flower visit, it is likely to deposit it on the stigma. Only long tongued insects can take advantage of this flower and they need to develop an efficient way to approach this specially shaped blossom. After a few times they get better and better and proceed faster. The most common pollinators of violets are small, solitary bees.

Bumble bee visiting a jewelweed blossom

© Beatriz Moisset

Jewelweed (Impatiens) also possess a spur. The flower itself is a small chamber just a little larger than a bumble bee. The petals form a curtain that slightly blocks the entrance to this chamber. Bumble bees are pros at collecting nectar from these flowers. Their plump bodies fit inside the chamber like a finger in a glove and their long and flexible tongues are suited to the curved spur.

Columbine.

© Beatriz Moisset

Columbines have not one but five spurs. Each petal is shaped like a long hollow horn ending on a knob. This is where the nectar gathers. Long tongued insects and hummingbirds pollinate these flowers. In most species, the flower nods or points downward, and the spurs point to the sky. This arrangement seems to be agreeable to their most common pollinators, hummingbirds.

Columbine.

© Beatriz Moisset

By contrast, the flowers of the alpine columbine remain erect, don't nod. They are also creamy white, a color favored by moths. And thus, they are preferably pollinated by large moths, the so called hawkmoths. A few other species of columbines, including the Colorado blue columbine, also face upwards and are also pollinated by moths.

Columbine and carpenter bee

stealing nectar

© Beatriz Moisset

Jewelweed and ants

stealing nectar

© Beatriz Moisset

This specialization has advantages but it also has some disadvantages. Not all flower visitors behave like honest pollinators. These difficult flowers are an invitation to cheating. Some visitors learn to take a shortcut, especially if their tongues aren't long enough to reach the bottom of the spur. They approach the flower from the side. Perhaps, they can smell the sweets through the walls of the spur. A quick bite or a stab through the delicate petal may be all it takes to reach the hidden food. Carpenter bees, bumble bees and even ants have been seen performing this robbery.


List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2017

Butterfly Pollination

Fritillary butterfly on butterfly weed

© Beatriz Moisset

When you mention pollinators to people, the immediate answer is: bees and butterflies. Bees, yes, the 20,000 species or so do a huge percentage of pollination. Some plants depend entirely on bees for this function. However, when it comes to butterflies, a different story emerges. Other insects, such as flies, wasps and moths are known to do a respectable amount of pollination, probably far more than butterflies do. Some of the mentioned insects are indispensable to certain plants, such as figs, cacao and yucca. Some flies are used in farming.

A great variety of pollinators and flower visitors

© Beatriz Moisset

Butterflies visit flowers but that alone doesn't make them good pollinators. They are easily noticed because of their large size and color. That is why the general public takes notice, but biologists have not paid a lot of attention to the role of butterflies as pollinators. So it would be nice to know a little more about them and how much credit they deserve.

Bumble bee on Helenium

© Beatriz Moisset

Let us compare a bumble bee with a butterfly in a field full of ragworts, for instance. Ragworts are pretty, daisy-like, rather weedy yellow flowers. A bumble bee hastily gathers pollen and nectar and moves on quickly from blossom to blossom in one plant, next it moves on to the next plant and the next, without wasting any time. It finally rushes home to feed a hungry brood with the gathered supplies. A butterfly, on the other hand, is free from family obligations. It only needs some nectar to quench its thirst so it lazily sits on a flower, unfolds its long tongue and drinks at leisure. It takes off and wanders away apparently aimlessly. Farther down it may finally land on another flower and drink some more nectar. Later on it may visit another plant a good distance from the previous ones and so on.

It is obvious that the bumble bee performs more pollination because of its diligent behavior. However, the butterfly is doing something important by transporting pollen to plants that are a good distance from each other. It is performing cross pollination and ensuring a good mixing of genes. Plants benefit from this increase in genetic diversity. Furthermore, recently researchers have learned that the pollen, stuck to a butterfly's long tongue, stays fresh for a good time and ensures this valuable pollination at a distance.

Red banded hair streak butterfly on Helenium

© Beatriz Moisset

Butterflies seem to do more pollination in tropical regions than in temperate ones. Butterflies and hummingbirds are good at finding nectar inside long-necked or trumpet shaped flowers. They are attracted by red flowers, which are rather common in the tropics. Bees are color blind to the red color and prefer yellow and blue or purple ones. Butterflies, like hummingbirds, have a good vision for the red color.

A number of flowers are completely dependent on butterflies for pollination. Some South African orchids fall in this category. Another flower dependent on a butterfly for pollination is a member of the pea family, the Peacock Flower that grows in the Caribbean.

Orange sulphur butterfly on asters

Notice the long tongue

© Beatriz Moisset

In summary, butterflies, while not the most efficient pollinators, are important, even essential, in some instances.

Also see:
Pollinator Foraging Behavior and Gene Dispersal in Senecio (Compositae) (contribute to cross pollination, farther distances than bumble bees)

Zebra Longwing Butterfly (Heliconius charitonia)

Fritillary: A Pretty Butterfly and a Good Pollinator

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2017

Bees and Biodiversity

Bombus ternarius, Tricolored bumble bee on mountain mint

 Recently I discussed the idea of allowing dandelions on the lawn to benefit pollinators. I pointed out that such practice only benefits a handful of generalist pollinators, but not the specialists. The latter can be more numerous than the former when they are all counted. They also account for the wide diversity of nature.

Bombus impatiens, Common Eastern Bumble Bee on blanket flower

Andrena cornelli, Azalea andrena on azalea

Let me expand on the concept of biological diversity or, as it is often called by ecologists, biodiversity. There are 4,000 species of bees in North America, from the familiar, big and plump bumble bees to tiny bee species that remain unnoticed to all except to those who study bees. Bear in mind that even bumble bees aren't just one single species but about 46 in North America.

Augochlora pura on thistle

Nomada, cuckoo bee on spring beauty

Bee species vary not only in size but in many other ways. Some are active from early spring to the end of fall. Others complete their whole cycle in just a few weeks and remain dormant the rest of the year. Some are adapted to different climates and cover a large area, others are more limited in their geographic distribution.

There are even some species, called cuckoo bees, that don't bother raising a family. Instead, just as cuckoo birds, lay their eggs in the nests of other bees.

Some bees have a long tongue that enables them to reach into fairly deep throated flowers. Others can only visit flowers that are relatively flat and open. Finally, some are very particular about the flowers they visit.They collect pollen from only one species of plants (monolectic) or a few related species (oligolectic). They may visit a wider range of flowers for nectar, but only their choice plants will satisfy their pollen needs.

Agapostemon splendens on seaside goldenrod

Lasioglossum pilosum on coneflower

Losing a few of these specialists may not be catastrophic, but it is preferable to preserve as many of them as possible. A rich variety of species confers resilience to an ecosystem. This is why it is important to have a wide range of specialists along with the handful of generalists. One way to help the specialists is to plant a variety of native plants to ensure that some of them satisfy their needs.

Colletes on Cerceris canadensis

Bombus perplexus, confusing bumble bee on common milkweed

Long horned bee on sunflower

 All images © Beatriz Moisset

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2016
 

The flower reinvented

Dichromena latifolia or Rhynchospora latifolia, identified by Andrew Greller.

Sedges and grasses are wind pollinated and have no showy flowers. It is interesting that Narrow-Leaf White-topped Sedge evolved to attract pollinators and created a sort of flower for this purpose. The apparent petals are not the same as those of a real flower but modified leaves called bracts.

See: Plant Profiles. White Top Sedge

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2016

Thrifty flowers

Pollen is a valuable commodity. The less pollen needed, the more energy is left for other functions. Flowers resort to several strategies to economize on pollen. Some use a method called explosive pollination, others resort to buzz pollination. Both methods are well illustrated by official state flowers.

Mountain laurel in bloom. © Beatriz Moisset

Explosive Pollination of Mountain Laurels

Mountain laurel (Kalmia latifolia), Pennsylvania’s and Connecticut's state flower, has a singular way to ensure that its insect visitors carry pollen to other flowers of its species. The unopened blossoms present little knobs which give them a funny look. Their function becomes apparent when the flower opens. They are pockets that hold the anthers trapped. Anthers are the part of the flower that produces male cells, pollen.

Mountain laurel flower before an insect's visit.  © Beatriz Moisset

Flower tripped by an insect. © Beatriz Moisset

In most flowers the anthers are free and exposed to spread their pollen at the slightest touch of a flower visitor. The mountain laurel has a different strategy. The pollen is well protected against rain and wind; but, when a pollinator lands on the flower searching for nectar, the weight acts as a trigger, causing the taut stem of the anther to spring. The anther hits the pollinator gently on the back and gives it a dusting of pollen.

This method allows mountain laurel flowers to produce only a moderate amount of pollen because most of it ends up where it is intended, on the body of a pollinator, rather than being wasted in other ways.

Connecticut: Mountain laurel

Pennsylvania: Mountain laurel

Explosive Pollination of Pea-like Flowers

Texas Bluebonnet. Wikicommons © Jacopo Werther

Other flowers encase both the pollen-producing parts and the female parts, or stigma, into a sheath. Some members of the pea family, Fabaceae, have flowers that resemble a butterfly, this is why this subfamily is called Papilionoideae, papilio meaning butterfly. The top petal is large and shaped as the sail of a ship and is called the banner. Two side petals are called wings, and the bottom two petals are merged into one forming a sheath that encloses both the anthers and the stigma. This structure looks like the keel of a boat and it is so called.

Structure of a papilionoid flower. Wikicommons. © David Richfield

When a pollinator lands on a blossom, its weight triggers a mechanism causing the keel to spread open and the anthers and stigma jump up out of the enclosure. This is called tripping. The insect has to be heavy enough to cause such reaction. Some bumble bees are pros at this task; honey bees, on the other hand, dislike being pounced upon. After a few times, they learn to sneak around and steal the nectar through a small opening at the base of the keel. Only novices perform pollination. Once they learn this trick no more pollen is transferred to the stigmas. Nevertheless managed honey bees are widely used to pollinate alfalfa and clover. Bee hives provide a large labor force that makes up for this deficiency. Some bumble bees, especially the short-tongued species, are also inclined to a little larceny. However, they are generally considered highly competent pollinators of alfalfa and clover.

Clover, another papilionoid flower. © Beatriz Moisset

Texas’ bluebonnet (Lupinus) and Vermont’s red clover (Trifolium pratense) need to be tripped. Six species of lupines, all of them called bluebonnets because of their appearance, live in Texas. All six of them are considered the state flower. The red clover, Vermont’s state flower, on the other hand, is not a native plant. It is an important crop used to feed livestock.

Texas: Bluebonnet

Vermont: Red Clover

Buzz Pollination or the Salt Shaker Technique

Other flowers make the pollinators work for pollen in a different way. Interestingly enough, honey bees never learned how to do the job I will describe, but native bumble bees and numerous species of bees are real pros.

Azalea Andrena bee pollinating azalea. Observe the pores at the tips of the anthers. © Beatriz Moisset

In most flowers the pollen is made available to pollinators as soon as it is ripe. The anther splits open. We all have seen the golden dust many flowers have. If we touch it, it sticks to our fingers. Rhododendrons and azaleas do something else. They keep the pollen enclosed inside the anther. It can only come out through a small opening at the tip. Several other native flowers, like tomato and blueberry have a similar characteristic.

In order to extract it, the bee has to cling to the anther and give it a good shake. It accomplishes this by vibrating its flight muscles while keeping the wings still; it is like running the car engine in neutral. Pollen comes in clouds and clings to the body of the pollinator. Later, the bee proceeds to package its loot in the little baskets of the hind legs.

Buzz pollination of azalea. Video. © Beatriz Moisset

Two states have official flowers that exemplify this method of pollination, Washington has chosen the Coast Rhododendron (Rhododendron macrophyllum) and West Virginia has another species of Rhododendron (Rhododendron maximum). Georgia’s official wildflower, azalea (Rhododendron prunifolium), follows the same system of pollination; its official flower is the rose; but, fortunately, they decided to honor a native plant in addition to a non-native flower.

Georgia (official wildflower): Azalea

Washington: Coast Rhododendron

West Virginia: Rhododendron

Other plants select their pollinator clientele through other methods. Some hide the nectar rather than the pollen. A different set of skills are needed to deal with these flowers as we'll see in the next post.

References

Pollination of mountain laurel

Image illustrating the parts of a Papilionoid flower

Red clover pollination (also alfalfa)

Legume pollination

Bluebonnet pollination

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2015

The Earliest Pollinators: Beetles and Flies

Magnolia © Beatriz Moisset

 By the time the first flowering plants appeared on Earth there weren’t any bees or butterflies. Those superb pollinators would take millions of years to evolve from wasps and moths respectively. So, who would be attracted to flowers? Who would carry pollen?

Other insects, although not adapted to sipping nectar and storing pollen in little baskets, liked to visit flowering plants to eat the pollen. Sometimes, they also devoured the flowers themselves. Beetles and flies were among the earliest pollinators. These two groups of insects visit the flowers of magnolia and water lilies to this day. In general, flowers pollinated by beetles are cup-shaped to allow these insects to stay for some time. They are strongly scented by fruity or rotten smell. The petals may be tough and leathery, helping them to put up with the abuse; many of them are greenish or creamy white.

Tumbling flower beetles on magnolia © Beatriz Moisset

The state flower of Louisiana and of Mississippi is the Magnolia (Magnolia grandiflora) which is an example of some of the oldest flowering plants; it presents all the qualities listed above and it is pollinated by beetles that use the flowers as a singles bar. They stay for hours eating, drinking, mating and making a mess of the place. When they arrive, usually only the female part of the flower is mature enough, so if they carry pollen from other flowers they get cross-pollinated, but by the time the beetles leave, the stamens or male parts have become ripe. The visitors get easily dusted with it and ready to carry it to the next awaiting singles bar. Beetles and flies find a coating of nectar covering the petals that they can slurp as they go along.

Dance fly on Magnolia © Beatriz Moisset

It is worth mentioning here the tulip tree (Liriodendron tulipifera) because it is the state tree of Indiana, Kentucky and Tennessee. The state flowers of Indiana and Tennessee are not native; they are the peony and iris, respectively, so I like to think of the tulip tree blossom as the honorary state flower of these two states. The tulip tree is a relative of magnolias, equally ancient; its flower bears some resemblance to magnolias. It is also pollinated by beetles, although bees and other insects also contribute to its pollination.

Another ancient flower, the California poppy (Eschscholzia californica), California’s state flower is also pollinated by beetles in some instances. These are more numerous than bees in arid areas. Several species of bees, including honey bees also pollinate these flowers.

California poppy © Audrey. Flickr

State flowers that illustrate the earliest pollinators:
Louisiana: Magnolia

Mississippi: Magnolia

California: California Poppy

Once plants came up with this novel solution to their fertilization process, there was no stopping them. Evolution accelerated and an ever growing variety of flowering plants emerged from the older lineages. In turn, more insects evolved to take advantage of this resource. This is how some carnivorous wasps went vegetarian. They became what we now know as bees. Pollen and nectar supplied all their needs.

Also some moths developed a taste for nectar during their adult life. Unlike most moths, they were diurnal and often sported fancy colors. In other words, they evolved into butterflies. Being frequent flower visitors they became pollinators. This is not to say that wasps and moths, the predecessors of bees and butterflies don’t pollinate. In fact some of them are valuable and are highly specialized ones.

The following posts deal with these pollinators and their flowers.  We will start with the ones who invite a wide assortment of guests. They have mass appeal and several state flowers illustrate this nicely.

Pollinators of Official State Flowers 
Mass Appeal and Pollination

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2015

Pollinators of Official State Flowers

A tale of pollinators and pollination

as told by the official state flowers

 

We love flowers for their beauty and for the impact they have on diverse aspects of our lives. That is why we honor them by choosing an official state flower for each state of the union. A look at the list of state flowers reveals an amazing variety of shapes, colors, perfumes and blooming seasons. Some flowers are open and rather flat; others are elongated, trumpet like, with spurs, or intricately shaped. They may be grouped in clusters or stand alone. They come in a rainbow of colors and their scents are equally varied. Some bloom briefly in just one season, others do it for a longer time.

Why do plants have flowers and why is there such a variety? We seldom think about a flower’s function.  Some even feel that they were put here for our enjoyment. The fact is that their whole purpose is to attract pollinators, those love messengers that carry pollen from blossom to blossom ensuring the development of fruits and seeds and thus the future of the plant’s species. The great variety of flowers is a sign of the diversity of their pollinators. Both the flower and the pollinator complement each other to the point that, in some cases, only one kind of pollinator can perform the job for a particular kind of plant. This mutual fine tuning is the result of a long process of co-evolution. Often one can tell the type of pollinator by looking at the structure of the flower. For instance, flat, open flowers can be pollinated by short tongued insects; longer ones require longer tongued visitors. Tubular flowers are often pollinated by hummingbirds or very long-tongued moths. Night-bloomers are pollinated by night-flyers such as hawk moths or bats.

We often think of the honey bee as the ultimate pollinator and we seldom recognize the fact that many other insects, as well as some other creatures perform that job, in fact many plants have absolutely no use for honey bees. It is true that honey bees are incredibly adaptable and that they visit a wide array of flowers through several seasons, we could say that they are “Jacks of all trades” but we must remember the second half of that saying: “and masters of none”. In many instances flowers fare better in the absence of honey bees because some of them have developed a long standing partnership with their respective pollinators. Honey bees could interfere with such specialized pollinators.

Years ago, I was looking at a book on state flowers and was astonished at their variety. It occurred to me that it was possible to teach an entire course on pollination using state flowers as examples. All it takes is one look at the assortment of state flowers to see that there must be a similar diversity of pollinators belonging to several different groups of animals, not just bees, but also flies, butterflies, moths, beetles, and even bats and birds. Maybe some day, the states will recognize the importance of pollinators and decide to honor them also. After all, flowers would not exist without pollinators.

Some flowers accept a variety of pollinators, for instance, black eyed Susan (Maryland’s state flower) and goldenrod (state flower of Kentucky, Nebraska and South Carolina). Others are more selective, such as the flowering dogwood (state flower of North Carolina and Virginia). A few are extremely specialized like the yucca (state flower of New Mexico), which needs a tiny moth. No one else can do the job. Still others require unusual pollinators like the saguaro (state flower of Arizona) whose main pollinators are bats, or columbines (state flower of Colorado) which are pollinated by hummingbirds.

Curiously, thirteen states have chosen official state flowers that are not native and therefore not truly representative of the state. Fortunately seven of them decided to add an official state wildflower, for instance, the state flower of Ohio is the carnation and its wildflower is the white trillium. I will mention a few of them because they contribute something valuable to this tale of pollination. In other cases, I will refer to the state tree if it bears flowers that add something to the pollination story.

One may wonder why some states chose flowers native to the old world rather than those that represent the state flora. It seems that state flowers were chosen more for their beauty, or economic importance. Perhaps part of the explanation is that this is such a nation of immigrants that many people are more familiar with the rose or the carnation than with any local flowers. Economic importance counts too. Thus, it comes as no surprise that Florida chose the orange blossom as a state flower.

In a few cases there is some confusion about the choice of state flower. This is not surprising considering that legislators are not botanists. The common name could include only one or several species of similar plants. Which one of several violets is the state symbol? Those states that chose the rose, were they thinking of a native species of rose, or one of the common cultivated varieties? Different sources give slightly different interpretations to these choices. In general, I will follow the scientific nomenclature used by the United States National Arboretum, but I may include other interpretations in some instances if they illustrate an interesting pollination point.

Here is the story of pollination and pollinators as told through the examples of official state flowers. In the next post I will describe the kind of pollination that took place long before there were any insects or other animals to do the job, in fact, long before there were flowers. Then, I will examine the earliest forms of insect pollination. In following posts I will cover an assortment of floral strategies, from the ones that attract hordes of different pollinators to the specialists that prefer to deal with a select number of helpers or even just one. I will include some strategies that include nasty tricks played on pollinators and also an intriguing phenomenon, toxic nectar. It makes one wonder why a flower would want to make its pollinators sick. I haven’t forgotten pollinators of a different kind, non-insect ones, birds and bats. Finally, to wrap up this tale, I will take a look at state flowers and pollinators of economic importance.

More on pollinators and state flowers

Before there were Flowers: Wind Pollination

The Earliest Pollinators: Beetles and Flies

Mass Appeal and Pollination
This Way to the Restaurant

 

References

US National Arboretum. Trees and Flowers

State Symbols, USA

Netstate. Official State Flowers 

Dowden, Anne O. State Flowers. 1978
Cooper, Jason, The Rourke Guide to State Symbols. Flowers. 194

List of articles
Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2015

Alfalfa Pollination

Large commercial alfalfa field

requiring managed beehives because of its size

© Vapampidis. Wikicommons

What is the most important insect-pollinated crop? Not a fruit or a vegetable but alfalfa. Yes, alfalfa, not because we consume large amounts of their sprouts, but because cattle needs this food. Thus: no alfalfa, no beef or milk.

This crop was first introduced in California during the gold rush. Alfalfa farming grew from there at a steady pace to what it is today, the third largest crop, after corn and soy bean. A few species of bumble bees and solitary bees took a look at this exotic flower, found it to their liking and proceeded to pollinate it. It wasn't a big leap; this plant's blossoms resemble those of other members of the pea or bean family. The native pollinators were familiar with bean flowers and adapted easily to the new arrival.

Alfalfa blossom. H. © Zel. Wikicommons

Peas, beans, alfalfa, clover and several other plants have butterfly-like (papilionaceous) flowers. The lower petals form an enclosure, shaped like the keel of a boat. This structure holds the sexual parts, the anthers and pistil. When an insect lands on the flower, a trigger mechanism makes it snap open or trip the flower. This is how pollination is accomplished.

Honey bees were not present in California when the earliest fields of alfalfa were cultivated. The first beehive arrived in 1853, just one solitary hive; a few others had died in transit. It took many years for the honey bee populations to build up to significant levels. This didn't matter because the wild bees did an excellent job.

New Zealand wasn't so lucky when it started growing alfalfa to feed the recently introduced cattle. The few native pollinators were stumped by the new flower. They lacked the necessary equipment and dismissed the strange blossoms. Year after year, hay grew luxuriantly, but no seeds. Alfalfa growers resorted to importing a few species of bumble bees from Europe to cut down the expenses of having to buy seed every year. Thus, industrious bumble bees saved the day in that country.

Scotch broom, a papilionaceous flower, being tripped. © Beatriz Moisset

 Honey bees detest the rough treatment alfalfa flowers subject them to and soon learn a trick of their own. They enter the flower from the side and help themselves to nectar without tripping its mechanism. Only naïve, youthful ones pollinate flowers. Despite the honey bees' poor performance, most alfalfa farmers resort to them because of the convenience in using a managed species.

In addition to the honey bee, two other species of alfalfa pollinators are managed to some extent and used commercially. They are the Japanese alfalfa leafcutter bee and the native alkali bee.

The populations of native bees have been severely reduced in the last one hundred years largely because of intensive agriculture. Restoring their numbers and putting them to work in alfalfa fields would be an arduous task but a worthy one. Some farmers find that, when they include flowering and nesting site places in their fields or orchards, the health of the crop improves and the need for pesticides diminishes. Thus, alfalfa pollination could be done entirely and more efficiently by native bees. This form of agriculture would be more sustainable than the present methods.

List of articles
Bring Back the Native Pollinators
Will We all Die if Honey Bees Disappear?
Growing Insects: Farmers Can Help to Bring Back Pollinators
Organic Farming for Bees

Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2014

Beginners Guide to Pollinators

Read the review by Kathy Keatley Garvey at the Bug Squad website, For Beginners, a Guide to Pollinators

So many flowers.  So many pollinators. So many floral visitors.
On every field trip, we see something new and different.
With so much interest in pollinators, it's good to see that biologist Beatriz Moisset has written a downloadable book, "A Beginners Guide to Pollinators and other Flower Visitors." It's meant for young adults and beginners.

Beginners Guide to Pollinators and other Flower Visitors available at:

Barnes & Noble
Lulu.com

iTunes
Amazon