Bees are harmed by nativism

As our readers know, there are many reasons why we are opposed to the projects that are billed as native plant “restorations” but, in fact, often do a great deal of damage to the environment.  Of the many bogus justifications for these harmful projects, one of the most patently false is that the projects benefit wildlife.  Today, we are publishing a letter from one of our readers about the many ways in which nativism is harmful to bees.

“I thought of you, and your ongoing fight against short-sighted nativism, yesterday as I was doing research for a project on bees. I was interviewing a second-generation beekeeper, who’s working closely with geneticists and entomologists to develop hardy strains of bees, and he mentioned two things I thought might help to highlight how the actions of groups like the NAP may actually be contributing to colony collapse:

  1. The chemicals they use. Of course, it’s been broadly publicized that glyphosate and neonicotinoids are harmful to bees, and the AG industry folks (and possibly the native plant folks?) counter that they are far less deadly to honey bees than other types of herbicides and pesticides…but the beekeeper I spoke with indicated that saying something is “less deadly” to bees misses the harm these chemicals do to colonies by weakening their ability to fight viruses, mites, etc. Bees foraging in chemical-laden fields bring residues of these compounds back to the hive, to the queen, which he likened to “placing a pregnant woman in a refinery.” The result is a dramatically shortened lifespan for the queen and a colony that’s less strong and healthy, with lower resistance to common diseases. So the chemical may not kill the bees outright, but it still contributes to their death in the end.
  2. Honeybee on oxalis flower, another non-native plant being eradicated with herbicide.
    Honeybee on oxalis flower, another non-native plant being eradicated with herbicide.

    Honey bees are not native to America; they’re European. And the push to eradicate non-native “weeds” has decimated their forage…essentially starving them out. He cited the case of yellow star thistle, which, he said, may have come over from Europe in the wool of sheep. Highly invasive, it used to be everywhere in CA, and it was an important source of nectar and pollen for honeybees. Then, a few decades ago, the government introduced weevils to control the plant, in the process depriving the bees of a vital food source. Beekeepers have had to range further and further afield to find areas with adequate forage for their bees.

Bumblebee on Cotoneaster, Albany Bulb. Another target for eradication.
Bumblebee on Cotoneaster, Albany Bulb. Another target for eradication.

Of course, big agriculture (subsidized by the government) has contributed to the problem as well, by plowing up land that used to grow clover and alfalfa in favor of corn (for ethanol) and soybeans. But, for me anyway, this information about non-native bees needing non-native plants was a revelation…. a real ‘a-ha’ moment that I thought could be useful in waking up well-meaning folks who may equate “native plants” with “good for bees.”

Oh, and the beekeeper also told me that one third of the food Americans eat is pollinated by honey bees….are we willing to reduce our food supply by 1/3 for the sake of “restoring” a landscape native to a time when agriculture was not prominent in California?”

The value of yellow star-thistle to bees is but one example of the value of non-native plants to insects and other animals.  In the case of bees, the eradication of hundreds of thousands of eucalyptus trees all over California has deprived bees and hummingbirds of one of the few sources of winter nectar in California.  Eucalyptus blooms from December to May, at a time when there are few other sources of nectar.  HERE is an article about the loss of this important resource to bee keepers in California.

Eucalyptus and bee. Painting by Brian Stewart.
Eucalyptus and bee. Painting by Brian Stewart.

Yellow star-thistle is one of many eradication targets of nativists in California.  East Bay Regional Park District (EBRPD) has been trying to eradicate it in their parks for decades.  We recently learned that EBRPD was planning an aerial spraying of herbicide from a helicopter on 200 acres of yellow star thistle in Briones Park.   This was a particularly controversial herbicide application for several reasons:

  • Briones Park is adjacent to the watershed surrounding Briones Reservoir, which stores the drinking water of surrounding communities.briones_450w_32c
  • The herbicide EBRPD was planning to use was Milestone, which is known to be very mobile and persistent in the soil. For that reason, the State of New York refused to approve the sale of Milestone because they were concerned about contamination of ground water.
  • Aerial spraying of pesticides by helicopter is the most dangerous application method because it greatly increases the chances of drift into non-target areas, including residential areas.

Our team of collaborators jumped into action to prevent this spraying from being done.  We organized a telephone and email campaign directed to responsible staff and Board members at both East Bay Regional Park District and East Bay Municipal Water District, which is responsible for drinking water in the East Bay.

I am pleased to report that EBRPD announced within a few days of our campaign that they were permanently cancelling this aerial application of herbicides at Briones Park.  They will continue to try to eradicate yellow star thistle using other methods.

Lessons learned

When pesticides are used in native plant “restorations,” the claim that such projects are beneficial seem utterly dishonest.  Beneficial to whom?  Certainly not the animals and humans who are exposed to these toxic chemicals.

If the public does not want public land managers to use pesticides on our public lands, we must object when they do.  If we don’t object, we get the land management we deserve.  You will be alerted to such opportunities to participate in these campaigns to influence land managers by “liking” Facebook pages:  “Death of a Million Trees” and “Save the East Bay Hills.”

It is a team effort to learn about what is happening in our public lands and to participate in the decisions that affect our communities.  We are therefore grateful to the reader who shared her conversation with a beekeeper.  We encourage others to share their knowledge so that we can be as effective as possible.  Knowledge is power!

Are native species inherently superior to non-native species?

The native plant movement is based on the fundamental assumption that native species of plants and animals are inherently superior to non-native species.  The basis of this assumption seems to vary.  Sometimes the explanation offered is as simple as “the non-native doesn’t belong here.”  It’s not clear what that statement means.  Putting it in the best light, it implies that there is some optimal ecology that is best represented by exclusively native species.  A less generous interpretation would be that non-native plant and animal species are the non-human equivalent of illegal immigrants

We will examine this claim of the superiority of native species in the context of bees to make the point that nature is complex and cannot be oversimplified by such a sweeping generalization.

Professor Gordon Frankie, our local expert on the bees of the Bay Area, says that native bees are superior pollinators to the European honeybee.  If that were true, we would consider that a legitimate basis for the judgment that, in this case, the native bee is superior to the non-native bee.  However, the evidence available to us suggests that a comparison of the native to the non-native bee is more complicated.

In considering this question, we will focus on agriculture rather than residential gardens, because agriculture is economically more important and for the same reason more is known about the role of bees in agriculture.

Why would native bees be superior pollinators than non-native bees?

We know of two specific examples of native bees that are more effective pollinators of agricultural crops.  Both cases illustrate the pros and cons of native bees as agricultural pollinators.

Bumblebee on Cotoneaster, Albany Bulb

There are some crops—tomatoes, cranberries, blueberries, eggplants, and kiwi fruits—that are effectively pollinated by native bumblebees (Bombus) because of their unique method of pollination.  This method is called “buzz-pollination” or “sonication” and it is described as “an intense vibration, like a tuning fork being struck, pollen gathered from other flowers literally exploded off Bombus.”(1)

Unfortunately, though its pollination technique is superior, other characteristics of the native bumblebee have limited its usefulness in agriculture.  The crops with which it is most effective produce only pollen.  Therefore, the bumblebee must be provided with an alternate source of nectar to fulfill its dietary needs.(2)  

The bumblebee, like most native bees, is solitary.  It does not live in hives like the social European honeybee.  Therefore, it cannot be transported where and when it is needed, as the honeybee can.  An attempt at a high-tech solution to this limitation ended in disaster:  “In the 1990s, a bumblebee species Bombus occidentalis, was made extinct when experimenting breeders mixed species in Europe and shipped queens back to America.  The queens carried with them an exotic disease that Bombus occidentalis has no immunity for.”   Growers of tomatoes are now “forced to resort to less efficient pollinators.”  (Schacker 2008). 

Another example of a native bee that is a superior pollinator of an agricultural crop is the alkali bee which is the most efficient pollinator of alfalfa, a crop that is essential to the dairy and beef industries.  “Alfalfa flowers…keep their sexual parts hidden, under tension like a spring.  Bees must trip the spring to get at the pollen, and in so doing, they are hit on the head—something honey bees are not particularly fond of.  The alkali bees…don’t mind getting hit on the noggin and will happily pollinate a field of alfalfa.”  (Schacker 2008). 

Native bee approaching nest in ground, Albany Bulb

Unfortunately, the alkali bee, like 85% of native bees in the US, nests in the ground, in particular the alkaline soils of the western US for which it is named.  As cropland in the west expanded, the alkali bee was virtually wiped out by plowing up the ground in which it nested.  A leafcutter bee was imported from Canada as a substitute, but a fungus is now infecting its larvae. (Schacker 2008)

These disadvantages of native bees can be compensated for by providing nesting and nectar sources adjacent to croplands.  These hedgerows must be large enough to provide sufficient nesting opportunities and nectar sources. 

However, such hedgerows do not solve all the potential problems of using native bees as pollinators.  Because the bees are resident year around and cannot be transported, they cannot be removed when the crops are sprayed with pesticides.  And the pesticides are very damaging to the bees.  Therefore, a commitment to providing hedgerows for a resident bee population is also a commitment to organic agriculture, i.e., without using pesticides. 

This is not to say that the honeybees aren’t being adversely affected by the use of pesticides in the crops they are pollinating.  The impact of pesticides on  honeybees would be exacerbated if they were resident when pesticides were applied to the crop.  As it is, the honeybee is being affected by the residues of the pesticides on the crops they pollinate.  This is considered one of the primary reasons for Colony Collapse Disorder of commercial honeybees which has been destroying about one-third of commercial honeybee hives in the past few years.

Unlike most native bees, the European honeybee does not hibernate.  It is therefore available year around to be transported where and when it is needed.  Most native bees hibernate, but not necessarily at the same time.  Different species of native bees hibernate at different times and are therefore available for pollination at different times. 

Most native bees are more selective in their pollination than the European honeybee which is an extreme generalist:  “honeybees have the greatest pollen dietary range…of any known pollinator.” Although there are “only a handful of well-documented cases in North America of truly monolectic bees [a bee that visits only one kind of flower]” (Buchmann 1996), the flower preferences of native bees are narrower than that of the European honeybee.  While some native bees may prefer native plants, honeybees are willing to pollinate both native and non-native plants.  This is important because virtually all of our agricultural crops are non-native.

Native bees are not inherently superior to non-native bees

Honeybee hives, USDA photo

In summary, the European honeybee has several important advantages over native bees as pollinators of agricultural crops:

  • Because the honeybee is a social bee that lives in hives, it can:
    • Be transported where and when it is needed
    • Be removed from the agricultural crop when it is sprayed with pesticides
    • Does not need to be provided with nesting space and an alternate food supply
  • The honeybee is available for pollination services year around because it does not hibernate.
  • The honeybee pollinates a wider range of flowers than most native bees.

While native bees may be more efficient pollinators of residential gardens, there are a number of disadvantages to using native bees for agricultural pollination.  Although many of these obstacles can be overcome with greater use of resources, we cannot agree with the assumption of native plant advocates that native bees are inherently superior to the non-native European honeybee.  As with all sweeping generalizations, the truth is usually more complicated because nature is complex and man’s understanding of it is limited.


(1) Schacker, Michael, A Spring without Bees, Lyons Press, Guilford, Conn, 2008.

(2) Buchmann, S, and Nabhan, G, The Forgotten Pollinators, Island Press, 1996

“Mulch Madness” and other restoration mistakes

Thanks to Professor Gordon Frankie (UC Berkeley), we have learned a lot about the bees in the Bay Area.  He has been studying our bees for over 20 years and has made a wealth of interesting information available on his website.

Native bee (Anthrophora urbana) approaching nest in ground at Albany Bulb

Unlike the European honeybee, our native bees are usually solitary.  That is, they do not live in social colonies such as the hives of the European honeybee.   Most (60-70%) California native bees live in small nests in the ground.  Although they may produce enough honey to feed their own young, they don’t store an excess of honey like the honeybee.

Professor Frankie has identified one of the biggest challenges to native bees in urban gardens, “Mulch Madness.” 

“[If] you happen to be one of the many ground-nesting bees that looks for garden sites for digging small tunnels where you will lay your eggs in individually-made brood cells that you will provision with pollen and some nectar, [you have a new problem in urban gardens]…Something has happened in recent years to those favored bare dirt sites that makes your task much harder and oftentimes impossible.  MULCH MADNESS has arrived and has become a highly promoted ‘eco-friendly’ method for suppressing weeds, conserving water, and unknowingly discouraging ground-nesting bees!”

Anyone who is familiar with native plant restorations knows that most are covered in a thick layer of mulch.  When tree removals are required for a restoration, the mulch is usually composed of the chips of the trees that have been cut down.  The projects of UC Berkeley for which UC is applying for FEMA funding (based on its claim that the clear-cutting of all non-native trees will reduce fire hazards) say specifically that the clear-cut areas will be covered with 24 inches of mulch composed of the chips of the destroyed trees.

The UC Berkeley projects also claim that native vegetation will return to these clear-cut areas without being planted, based on an assumption that the seeds of native plants are dormant in the soil.  One wonders how these seeds would be able to germinate when covered with 24 inches of mulch, or how the sprouts could penetrate it.  Their proposal contains the fanciful suggestion that squirrels will plant the acorns of oaks in the mulch, which may be true of the oaks, but is an unlikely scenario for the many other native plants and trees which UC claims will populate their “restorations” without being planted.

Accommodating bees in native plant restorations

In the unlikely event that native plants would emerge from this tomb of mulch, they won’t find a population of bees to pollinate them in the future because bees will not be able to populate these projects:  “bees will not dig through a thick layer of mulch.”  Frankie suggests that “about 50% of your garden be left in bare dirt for the bees and other organisms.”  Studies indicate that it will take between 10 and 15 years for 24 inches of mulch to decompose.

Native plant restorations also require the use of herbicides.  A particularly toxic herbicide, Garlon, is used to kill the roots of the non-native trees after they have been cut down.  If the stump isn’t sprayed with this herbicide immediately, the tree will resprout.  The plans for the UC Berkeley projects say that retreatment with this herbicide is required twice per year for 10 years.  Although insecticides are considered one of the primary reasons why bee populations are declining in the United States, less is known about the effect of herbicides on bees and other insects, because testing of these chemicals is minimal. Some scientists believe that all pesticides (both insecticides and herbicides) are more harmful to bees and other animals than we presently know.*  Professor Frankie recommends against the use of all “synthetic chemicals” in a garden in which bees are welcome.

Would native plant restorations benefit from more bees?

The restorations with which we are familiar in the San Francisco Bay Area are often unsuccessful.  That is, they are not usually populated by native plants unless they have been intensively planted, weeded, and irrigated.  Few managers of public lands have the resources for such intensive gardening.  UC Berkeley has been clear-cutting non-native trees on its properties for about 10 years, so we can visit some of those areas to see the results of such projects.  They are now weedy messes, as shown in this photograph.

Results of clear-cutting non-native trees, UC Berkeley project

The use of heavy mulches and herbicides in native plant restorations raises these questions:    Would using less mulch and herbicide attract more bees?  Would more bees benefit the native plants?  Would restorations be more successful if they were more attractive places for bees?  We don’t claim to know the answers to these questions.  However, we don’t think that the managers of these projects know the answers either.

Would scientific methods produce more successful native plant restorations?

What the managers of these projects call “adaptive management,” we call “trial-and-error.”  There is no science involved in these projects.  Control areas are not set up to test questions such as “Will a more bee-friendly environment benefit our projects?”    We think a more methodical approach to these efforts would be less wasteful and more successful.  If we could see more success, perhaps we would be less opposed to what seems like the needless destruction of non-native trees.  As it is, the consistently poor results do not justify the destruction that we witness.


* Schacker, Michael, A Spring without Bees, Lyons Press, Guilford, Connecticut, 2008.

The Bees of Berkeley

Gordon Frankie is a Professor in the Department of Environmental Science, Policy and Management at UC Berkeley.  He has been studying the preferences of bees in northern California for over 20 years.  In 2002 he published an article in Fremontia, the journal of the California Native Plant Society, reporting on the preliminary results of his study.*

First, a word about the methods used in his study.  His research team visited the residential gardens of north Berkeley and Albany twice per week for three years, 1999 to 2002.  In the first stage of the study, the team identified the plants that were being visited by bees.  In the third year, they focused on counting the number of visits made to the identified “bee plants” by each species of bee.

The plants of Berkeley

Frankie’s team reports having identified 600-700 different varieties of non-native plants in the study area.  Native plants were defined as those that occur historically only in northern California.  Only 50 species of native plants were identified in the study area.

The bees of Berkeley

Frankie was surprised by the diversity of the bee population found by his research team.  They report having identified 74 different species of bees (updated on his website to 81).  Of those, only two were non-native bees (the European honeybee and the leaf cutting alfalfa bee).  Putting these numbers into perspective, there are approximately 1,600 species of bees in California and about 4,000 known to occur in the U.S.  Frankie reported that the population of European honeybees in the study area has declined significantly in the past 10 to 15 years.

What do the bees of Berkeley want?

The bees were observed visiting a small number of the total number of flowering plants available to them.  Only 72 species of flowering plants were visited by bees often enough to be counted by this study as “bee plants,” about 10% of the total number of flowering plants available to them.  Fifty-three of the “bee plants” were non-native and 19 were natives. 

Native bumblebee on non-native cotoneaster, Albany Bulb, Albany, California

While the bees of Berkeley are using a higher percentage of the available native plants (38%) than they are of non-native plants (8%), the percentage of non-native plants they are using is nearly 75% of all the flowers they are using.   Clearly, the non-native plants are important to the bees of Berkeley.

Frankie explains that many non-native plants are not useful to bees because they have been cultivated for looks, rather than for the nectar and pollen needed by the bees.  However, on his website, he updates his research with some strong recommendations to include both natives and non-natives in our gardens both for the benefit of the bees and the benefit of native plants.

Non-native plants extend the blooming period in our gardens, which provides food to the bees for a longer period of time:

“California native [plants] tend to flower in early spring and summer, while non-native ornamentals bloom mainly in late summer to fall, so a combination of both would be ideal for attracting the highest potential density of bees.”

Also, when our gardens attract more bees, all the plants in our gardens benefit from their pollination services, which will also benefit the native plants in our gardens:

“If your priority is a healthy garden, it makes good ecological sense to consider your plants’ bee-attractiveness, rather than focusing exclusively on whether one hundred percent of your plants are natives.  Even if your priority is to have a native garden, it can be highly advantageous to include even a couple of exotic plants on the basis of their bee-attractiveness.  The bees they attract will help your natives thrive.”

Frankie reminds us that the bees don’t care about the nativity of the plants that they use. 

Insects and other wild animals make no distinction between weeds and plants we put in our gardens.  From the perspective of the bee, any plant that provides quality pollen and nectar is attractive.  For the short period they are in bloom, weeds such as dandelions and white clover provide bees with good sources of pollen and nectar.”

Opening our minds to the benefits of non-native plants

The bees of Berkeley remind us that the obsession with native plants is a human hang up that is not shared by animals.  They consider the nativity of the plants that are useful to them to be irrelevant.  So should we. 


* Gordon Frankie, et al, “Bees in Berkeley,” Fremontia, July/October 2002

Destruction of eucalyptus threatens bees

The Pt Reyes Light received a Letter to the Editor in response to its series about the destruction of eucalyptus trees.  The author of the letter explains that eucalypts are one of the few sources of nectar during the winter, that the nectar is vital to the survival of bees over the winter, and that the bees are essential to California agriculture.  The letter was published in the Light on January 6th and is reprinted here with permission:

Think before you cut

Dear Editor,

The recent articles in the Light regarding the Park’s and other’s plans to eradicate eucalyptus from California fail to take into consideration one critical aspect of the need for eucalyptus in the continuation of agriculture in the state.

The common honeybee was introduced to California in the mid-19th century, around the same time as Blue Gum Eucalyptus. Each spring and summer, honeybees gather huge amounts of nectar from flowers and store it in the form of honey so they will have enough food to make it through the winter, when the weather is too cold and rainy and flowers are too few to provide food for the bees. 

In autumn, each hive greatly reduces its number of bees in order to survive the winter on the honey they stored. This is done by the queen laying fewer eggs and thus not replacing the bees that naturally die. Hives of 40,000 to 50,000 bees in summer drop to 10,000 bees in winter.

During December and early January, bees hover in a tight cluster, keeping each other warm and living off the stored honey.  In early January the Queen again lays eggs in ever-increasing numbers each day; larvae and then newly-hatched bees must be fed huge amounts of honey to support rapid growth. The demand for honey increases exponentially and if honey stores are not enough, the hive can starve to death just before warmer, drier weather and its tons of flowering plants arrives. 

But in California we have periods of sunny, warm days, in January and especially February. These allow bees to forage for nectar to supplement depleted stores in their hives and insure their continuation.  But what is blooming in January and February, when bees are in desperate need of nectar plants? Acacia, almond, ceonothus, manzanita, mustard, rosemary and some fruit trees bloom for short periods of time, but their small number and smaller sizes do not always guarantee enough blossoms. And any hard rain or wind can destroy whatever blossoms there are. 

Eucalyptus, on average 100-feet high and 30 to 50-feet wide, has tens of thousands of nectar-filled blossoms per tree.  It blooms throughout California from late January through mid-May, ensuring an abundant supply of nectar for hives at the time of their most critical need.

Prior to the arrival of the honeybee in California, the state population was 1 million people and agriculture consisted of wheat, barley, cattle and sheep, all of which could easily survive without honeybees.  Today, with California growing much of the fruits, nuts and vegetables for the U.S., the honeybee is an intricate part of the continuation of agriculture. With the current problem of Colony Collapse Disorder, the fate of the honeybee is already precarious. Cut down all these Eucalyptus trees and the fate of thousands of hives of bees, and thus the continued pollination of our food crops, may be in serious jeopardy.  Think before you cut them down.

Cathleen Dorinson, Pt Reyes Station

Eucalyptus and Bee, painting by Brian Stewart
Research on Colony Collapse Disorder has identified reduced supplies of nectar as one of many factors in the failure of about 30% of commercial hives per year in the past few years.  Bees, already weakened by chronic exposure to pesticides and reduced food supplies, are unable to recover from the fungi, viruses, and parasites that are rampant in the “global diaspora of organisms.”   

Because of the role of pesticides in the death of bees, the eradication of eucalyptus exposes bees to  double jeopardy:  the loss of a major food source during the winter and exposure to the pesticides that are used to kill the roots of the eucalyptus trees.

Garlon with the active ingredient triclopyr, is the pesticide used by most managers of public lands to kill the roots of the eucalyptus after the trees are cut down.  Eucalyptus is a vigorous resprouter.   Unless the stump is poisoned immediately with a toxic pesticide, it will return ten-fold after it is cut down, or in the unlikely event that it burns down, or after a freeze deep and long enough to cause the tree to die back.

Garlon is known to be toxic to bees.  The Marin Municipal Water District quit using all pesticides on its properties in 2005 in response to public protests.  It hired a consultant to evaluate 5 pesticides for potential use in the future.  The risk assessment published in 2008  stated that Garlon was the most toxic of the 5 pesticides studied and that it was the most toxic to bees. The Marin Municipal Water District is presently seeking approval to begin using Roundup again.  It does not propose to use Garlon. 

The so-called Natural Areas Program in San Francisco, which is responsible for the care of approximately 1,000 acres of park land ironically called “natural areas” uses Garlon heavily.  About 75% of its pesticide applications (by volume and frequency) are of Garlon.  Could this be a factor in the collapse of several beehives recently reported in San Francisco? 

The East Bay Regional Park District used 34 gallons of Garlon in 2008.  How many more gallons of Garlon will be used by these managers of public lands when they cut down the hundreds of thousands of eucalyptus trees which they have proposed to destroy in their official plans?

Once again, we can’t make sense of the destructive actions of those who are damaging nature in the name of “restoring” nature.  In our view, it is a fundamental contradiction.