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Destruction of eucalyptus threatens bees

January 15, 2011

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.

10 Comments leave one →
  1. January 15, 2011 1:06 pm

    Thanks for this article. From what I’ve read, our urban bee-keepers are facing a rash of sudden colony collapses. The Natural Areas Progam in San Francisco uses not only Garlon, but Garlon and glyphosate (Roundup, Aquamaster) in combination, on areas where wildflowers like oxalis bloom. It would be great to have more research on this.

  2. January 17, 2011 8:23 am

    It’s a shame that Honey Bee’s are treated with so little respect by government bodies. The epa recently have approved a deadly pesticide and CCD is still prevalent across the United States. Add to this your point about eucalyptus trees and its a wonder that Bees survive at all. Honey Bees need to be given some sort of special protection before it’s too late! I will share your findings about eucalyptus trees on my blog.. lets spread the word.

    Million Trees Webmaster: Thank you for visiting the Million Trees blog and for spreading the word amongst beekeepers about the threats to bees posed by the use of herbicides and the destruction of their sources of winter nectar.

    When the EPA evaluates herbicides for approval, bees are the only insect they test. Surely the herbicides are equally harmful to other insects, but since they aren’t tested we are blissfully ignorant of what we are doing. Ironically, one of the major purposes of these native plant “restorations” is to reintroduce endangered butterflies where they have been extirpated. It seems likely that they are killing the butterflies as well.

    Forgive them, for they know not what they do.

Trackbacks

  1. Destruction of eucalyptus trees puts Honey Bees at risk
  2. “Mother Nature’s Melting Pot” « Death of a Million Trees
  3. Are native species inherently superior to non-native species? « Death of a Million Trees
  4. More evidence that eucalypts are not invasive « Death of a Million Trees
  5. Monarch butterflies in California need eucalyptus trees for their winter roost | Death of a Million Trees
  6. 2013 Progress Report | Death of a Million Trees
  7. California Invasive Plant Council‏: Remove Blue Gum Eucalyptus from the List of Invasive Plants | San Francisco Forest Alliance
  8. Monarch Butterflies in California Need Eucalyptus Trees for their Winter Roost | San Francisco Forest Alliance

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