The war on so-called “invasive species” continues to escalate. One of the indicators of this escalation is the recently revised California Invasive Plant Council’s (Cal-IPC) inventory of “invasive” plants. Nearly 100 plant species were added, a 50% increase in the inventory.
More alarming is that most of the additions to the list are not considered “invasive” in California. Rather, a new category of “potentially” invasive plants was created, based on their behavior elsewhere. Many of the plants in the new category are considered invasive in Hawaii, a place with a distinctly different climate than California. Hawaii is a tropical climate, hotter than much of California and wetter and more humid than everywhere in California.
The big increase in the number of plant species now designated as “invasive” in California is a concern partly because of the herbicides that are usually used to eradicate them. Not only do we lose that plant species in our landscape when it is added to the hit list, we can also expect to see an increase in the use of the herbicides that are used to kill it.
Increased use of herbicides
Native plant advocates are aggressively defending the use of herbicides. Policies and practices are being developed to accommodate increased use of herbicides on our public lands.
East Bay Municipal Utilities District (EBMUD) is evaluating its Integrated Pest Management Program (IPM), including practices and policies regarding pesticide use. The first draft of EBMUD’s revised IPM program was made available to the public in July 2017. The draft adds several new goals to the IPM program: “habitat protection and restoration,” reducing populations of “invasive plant species,” and “use of alternative vegetation such as native plants.” EBMUD is the supplier of our drinking water in the East Bay and the quality of the water they supply should be the top—if not the only—priority. If destroying non-native plants requires greater use of herbicides, that goal contradicts EBMUD’s obligation to providing safe drinking water.
San Francisco’s IPM program has also changed some policies to accommodate use of herbicides in parks on plants the Natural Resource Division of the parks department considers “invasive.” The parks department restricts all park access to the established trails in the 33 “natural areas” where non-native plants are eradicated and replaced by native plants. The new IPM policy permits the spraying of herbicides without posting pesticide application notices in places that are “publicly inaccessible.” In other words, pesticide application notices are no longer required in the “natural areas” unless herbicides are sprayed on the trails. One way to reduce the public’s opposition to pesticides is to hide their use and this policy seems designed to do that.
Update: The San Francisco Forest Alliance (SFFA) has informed me that Chris Geiger, head of San Francisco’s IPM program, has given assurances that the IPM program will no longer offer City departments a blanket exemption to apply herbicides without posting in areas the department considers “publicly inaccessible”. Previous to this, each land manager was empowered to make their own decisions as to which areas they considered “publicly inaccessible”. The IPM group did not provide oversight of the decisions or keep records of which areas were exempted. Now specific exemptions will be issued and recorded on the IPM exemptions webpage. Chris Geiger reports RPD will not be requesting any posting exemptions. SFFA is still waiting for formal written documentation of this change.
San Francisco’s IPM Program is also demonstrating its commitment to native plants and the eradication of non-native plants by sponsoring a webinar on October 5th, 2017, featuring Doug Tallamy: “The Plant-Pollinator Connection: Why Pollinators Need Native Plants.” Tallamy is the academic entomologist who has devoted his career to the promotion of native plants based on his claim that insects at the base of the food web are dependent upon native plants. He has said in many publications that non-native plants will cause the collapse of our ecosystems. Many of the statements he makes in support of his dire theory are not accurate.
This post will focus on the intersection of these symptoms of the escalating war on “invasive” plants: the expansion of California’s inventory of “invasive” plants and the closely associated claim that non-native plants must be eradicated because they compete with the native plants required by wildlife. We use buddleia, commonly known as butterfly bush, as an example.
Butterfly Bush (Buddleia): friend or enemy of butterflies?
Buddleia is one of 87 plant species recently added to Cal-IPC’s inventory of “invasive” plant because it is considered invasive outside of California. Buddleia is called butterfly bush because it produces large quantities of nectar that attract swarms of butterflies. Since buddleia is very appealing to butterflies, it is popular with gardeners who like to see butterflies in their gardens.
Since buddleia is obviously useful to butterflies and Doug Tallamy claims to be concerned about the welfare of our pollinators, why is he telling gardeners to quit planting buddleia? His advice is based on the fact that buddleia is considered invasive in some places and his belief that it will eventually be invasive everywhere. In fact, that’s his belief about all non-native plants: they may not be invasive now, but he predicts that eventually they all will be invasive.
Secondly, Tallamy argues that although buddleia provides food for butterflies, it is not a host plant for butterflies. The host plant is where butterflies lay their eggs and where the caterpillar feeds when the eggs hatch. The choice of host plant species is much smaller than the number of food plant species available to butterflies, but it is not as small as Tallamy thinks it is. Tallamy does not seem to realize that many plants are chemically similar, which enables butterflies to make a transition from a native plant to a chemically similar non-native plant. Here in California, many butterfly species have made that transition and a few butterfly species are dependent upon abundant non-native plants that are available year-around because their original native host plant is dormant much of the year.
Buddleia “starves” butterflies?
This is Tallamy’s apocalyptic prediction about the fate of butterflies if gardeners continue to plant buddleia:
“It’s no exaggeration to say that when you choose which plants to include in your garden, even the beautiful, seemingly harmless butterfly bush, you’re deciding if members of your community’s local food web will be nourished or unintentionally starved. And to get to that mind frame, which is a way of thinking that truly benefits nature, including its butterflies, you’re going to have to come to a harsh realization: You need to stop planting the butterfly bush—forever.” (1)
Ironically, this harsh verdict on buddleia was published by a blog entitled, “Organic Life.” Is Organic Life unaware of the fact that the most widely used method of eradicating non-native plants is spraying herbicides? The consequence of adding more plant species to the long list of “bad plants,” is more pesticide use. That’s not very “organic.”
What amoral, selfish gardener would plant buddleia in their garden after such a severe scolding? First, let’s stop and think about the logic of the claim that buddleia will disrupt the “food web” and starve butterflies. Since buddleia is an excellent source of nectar and swarms of butterflies are observed nectaring on buddleia, how could we be “starving” them? Professor Art Shapiro (UC Davis), our local butterfly expert, said when asked about this article, “The ‘disrupting food webs’ argument is ludicrous. It’s equivalent to saying that if you eat popcorn rather than apples, you’re contributing to unemployment in the apple-picking industry.”
Is buddleia a host plant for butterflies?
Now let’s consider the argument that we should not plant buddleia in our gardens because although it feeds butterflies, it isn’t their host plant where they lay their eggs. The problem with that argument is that it isn’t true!!
In 1940, Charles M. Dammers reported that the Variable Checkerspot (Euphydryas chalcedona) “can use” buddleia as a substitute for its usual native host in southern California desert-mountain areas, based on a laboratory study of the larval stages of its caterpillar on buddleia. In 2001, chemical analysis of buddleia found that it is chemically similar to the native host of the checkerspot, which confirmed the potential for such a substitution.
The first actual observation of checkerspot butterflies breeding spontaneously and successfully on buddleia was in Mariposa County, California in the Sierra Nevada foothills. “Mariposa” is Spanish for butterfly. Mariposa County was named by an early Spanish explorer who saw many butterflies near Chowchilla.
Checkerspot bred successfully on buddleia in 2005 and in subsequent years. This colony of checkerspot on buddleia was reported in 2009: “We conclude that buddleia davidii [and other species of buddleia] represents yet another exotic plant adopted as a larval host by a native California butterfly and that other members of the genus may also be used as the opportunity arises.” (2)
More recently, a gardener in Mendocino County also reported the use of buddleia as the host plant of checkerspot:
“By now I am questioning how it was that butterfly larvae were using my butterfly bush as a host plant, completely against everything I’d ever heard. How was this possible? I emailed Art Shapiro, a very well-known butterfly expert and author, sending him a pic. He wrote back to confirm they were butterfly larvae, but added, ‘These are not mourning cloak butterflies. They are checkerspots. And the only time I’m aware this has happened [like, ever, except one in a lab in 1940…] is in Mariposa County.’” (3)
Bad rap for non-native plants
When the native plant movement began some 30 years ago, native plant advocates promoted their agenda with a straight-forward claim that they are superior to non-native plants. The public was initially resistant to that argument because non-native plants have been around for a long time and people have become fond of them.
Native plant advocates began to fabricate stories about the evils of non-native plants to convince the public that eradicating them was necessary because they are harmful to wildlife and they damage the environment. The Million Trees blog was created to address those claims.
But Doug Tallamy’s active participation in the crusade against non-native plants is a special case because he is an academic entomologist, credentials that make him more influential with the public. For that reason, Million Trees has critiqued several of his publications. We publish this critique of Tallamy’s opinion of buddleia for several reasons:
- Buddleia is very useful to butterflies. The loss of buddleia in our gardens would be a loss to butterflies.
- San Francisco’s IPM program is using Doug Tallamy’s mistaken theories to promote the use of herbicides to eradicate non-native plants in San Francisco.
- Buddleia is one of 87 plants that have been classified as “invasive” by the California Invasive Plant Council despite the fact that it is NOT invasive in California. The expansion of the list of “invasive” plants in California to include plants that are NOT invasive in California, will increase the use of herbicides and will eliminate plants that are performing valuable ecological functions.
- https://www.rodalesorganiclife.com/garden/never-plant-butterfly-bush (N.B. The butterfly in the photo in this article is European Small Tortoiseshell, found in Britain and in Europe. The caterpillar in the photo is the monarch caterpillar on its host plant, milkweed. Buddleia is food for both of these butterfly species.)
- Arthur M. Shapiro and Katie Hertfelder, “Use of Buddleia as Host Plant by Euphydryas chalcedona in the Sierra Nevada foothills, California,” News of the Lepidopterists’ Society, Spring 2009
- http://plantwhateverbringsyoujoy.com/never-pull-up-and-discard-what-you-cannot-identify/
Conservation Sense and Nonsense 
Your article has convinced me that I need to plant buddleia for its beauty as well as its benefits for butterflies. Mr. Tallamy’s illogic reminds me of an Administration official that I despise.
Oh Madeline, you are so right. We need and have the right to have beautiful plants, and what a beautiful plant Buddleia is. And then we get to see the beautiful butterflies it attracts. (I love Checkerspots too and how wonderful to see the one laying her eggs.) I wish our yard was sunny enough to get one.
Thanks so much for the link to my blog post on Plant Whatever Brings You Joy highlighting this amazing story of discovering checkerspot caterpillars using my buddleia as a host plant. I’ve long been concerned about Doug Tallamy’s blanket advice to get rid of buddleia. I sent him link to our discovery and he was kind enough to leave a comment on my blog. 🙂 Also, please note that this happened in Mendocino Co., not Sonoma. I advised Art but I think the mistake had already been published and could not be corrected in the original.
Thanks! Kathryn
Thanks, Kathryn. I will make that correction.
I believe that what Doug Tollamy was saying in a somewhat disjointed way (was he quoted properly?) was that by your choice of plants in your garden you are influencing or determining the evolutionary path of butterfly species. My question is, on what ethical grounds do you think you have the right to do this, just to satisfy your selfish, anthropocentric desires, because of course you are planting buddleia in your gardens out of self-interest, for beauty, because you want to watch butterflies, etc.? Why should species be forced to switch to using different plants just because of human behavior? What is wrong with the native plant?
Webmaster: I am familiar with the “evolutionary trajectory” argument used by nativists to justify their ideology. Here is my rebuttal of that specious argument: https://milliontrees.me/2014/12/05/what-is-the-goal-of-ecological-restorations/
I am familiar with buddleia from Britain as a garden escapee that invades mostly waste ground, i.e., human modified environments. It is invasive, and likely to become more so as human-influenced habitats increase. California, with its diverse flora, simply does not need it.
Re listing potential invasive species, yes, sometimes the inclusions seem ridiculous as it seems very unlikely that the species will thrive under the new conditions, but the point of doing so is to alert the public and the appropriate management personal to possible occurrences of non-native species with a known track record for invasion. If occurrences are reported then the plants can be dispatched speedily, possibly with the minimum amount of herbicide – far less at any rate than may be needed if the introduction is allowed to become rampant. So the argument that listing potential invasive species increases the use of herbicide is not rationally valid.
My recommendation is that people should be planting native species (i.e., native to their area) in their gardens, and in the case of butterflies, including both the pollinator plant and the larval host plant. This way they will not need to use herbicides and will not run afoul of the anti-invasive contingent. I checked up on the native host plants of the variable checkerspot, by the way. They are varied, and many of them are showy – perfect for planting in the garden!
“…ethical…selfish…self-interested…” Again self-righteous native plant fanatics have appointed themselves judges of what is morally right or wrong. So presumptuous, so tiresome, so wrong. It is bizarre to claim the moral high ground for habitat destruction and pesticide use.
Neither Patricia, nor anyone else, knows the “evolutionary path” of a butterfly species, (nor any other species.) Using that phrase is a common rhetorical ploy, an attempt to sound scientific in the absence of science. Humans really don’t know that path, and certainly can’t determine that path. An additional host and/or food plant may influence that path, but just as likely in a way that benefits the butterfly rather than harms it.
If you target a plant for destruction, you will use more pesticides, not less. If you leave the plant alone in its environment you will use less pesticide. That’s rational.
As this blog says, ad infinitum: There is nothing wrong with native plants. Plant whatever you want in your garden. People who make different choices shouldn’t have to worry about the threat that they “run afoul of the anti-invasive contingent.” Mind your own business; practice your religion in private.
It is the destructiveness of “native plant restorations” on public land, and the phony science used to justify them, that rational people object to.
No herbicide is ever “needed.” Ignoring the health effects can be easier since we never know if that case of cancer we or a dear friend has is from a particular pesticide use, but I think a lot more people would not feel it’s justified if we did know. No more adding to chronic illness or cancer should be prioritized over humans’ obsession with killing plants.
Thank you of this enraging, heartbreaking post. Will these nativists never stop to think or feel about the effects of what they are doing to our environment? They have become a dictatorship where we have no vote as we watch beloved plants and forests destroyed for their human arrogance.
How invasive can Buddleia be? When I lived on a mountain in rural Ireland for three summer months, the one Buddleia we had was a relief with the color and butterflies. It certainly was not spreading, which would have been wonderful. The wind and rain limited what plants could grow there.
Part of what used to be so wonderful about the Bay Area was the diversity of plants from all over the world. Many of us are from places that are wastelands during some seasons, but here, someone is always blooming. Or was, since the goal now seems to be to kill them.
Yes, we have beautiful native plants, but they often need very different ecosystems, from arid to coastal to almost rain forest. Among of the most beautiful are the most delicate, and humans have destroyed some of the best wildflower areas. The climate change brought by humans is destroying other plants and ecosystems here. Why not love and nurture what most survive? Even if some humans hate them, native animals usually love and need them. And if people here are actually given a choice, we usually love the exotics too.
So many people are on drugs for depression, but plants blooming year round helps people’s mental states. I always think that the bright yellow acacias and broom blooming in the darkest months here could actually safe some lives. They certainly help winter be less bleak. But they should be killed? Can we vote on this?
I have planted buddleia only once…in my garden in San Francisco. It didn’t last long. San Francisco isn’t an easy place to be a gardener. My neighborhood was barren sand dunes just 40 years before we moved there. Over nearly 30 years we lived in San Francisco, there was a lot of trial and error in my garden. In the end, my garden was populated only by what survived. As Bev Jo says, I felt lucky to have anything growing in my garden.
Based on my experience with buddleia, I’d say calling it “invasive” in California is not justified. It certainly is not invasive in San Francisco.
I still do not hear a response to my question: “ Why should a species be forced through human actions to adapt to a non-native plant? As for moral high ground…” that’s interesting.
Webmaster: From the standpoint of butterflies, buddleia is a benefit, not a loss. It adds a source of food. Your projection of anthropomorphic motivation onto butterflies is a case of “pot-calls-kettle-black.”
Let’s see how ethically consistent you are. Most herbicides/pesticides are used in agriculture, not in restoration. Do you eat nothing but what is grown organically? Do you not eat bread, corn, rice, cows, canola oil? Does your house and furniture not have wood in it? Do you not expand your suburbia with your gardens of precious exotics and horticultural species into native habitats such as forests and deserts? It is non-natives (food and forest crops) – and invasives, – along with urban expansion, that destroy natural habitats, not anything that “nativists” advocate.
Webmaster: So, are you claiming that you don’t eat food or have furniture? Your viewpoint is an example of the misanthropy that pervades nativism in nature as well as nativism in politics. Yes, I buy only organic food.
And your commentators simply reinforce my point about Million Trees’ anthropocentric point of view, herbicides cause cancer in humans, plants prevent depression, are nice in gardens, etc. etc. Does no-one understand the value of a natural community of native plants, its beauty and adaptability, its role in a complete ecosystem, its value for scientific understanding, its right to exist, its ultimate benefit to humanity?
Webmaster: Pesticides are as harmful to animals as they are to humans. They are killing the butterflies you claim to be concerned about. We know more about the harm that pesticides do to humans because humans are conducting the laboratory studies. But when studies are conducted on animals, the results are much the same.
Let me tell you a story that illustrates my point of view. It takes place close to home for those of you who live in California. There is a tree called ironwood (Olneya tesota), endemic to the Sonoran desert. Endemics are closely followed by biologists because they occur only in the place they are endemic to, and if these populations become extirpated then the species as a whole goes extinct. Ironwood is also a keystone species, meaning other species depend upon it to live. It has been called a “resource island” allowing bacteria and fungi necessary for nutrient recycling to thrive in what would otherwise be sterile desert soil. Needless to say, plant islands provide resources for animals too.
But, ironwood is threatened by the spread of a grass, buffelgrass, Pennisetum ciliare (aka Cenchrus ciliaris) that has been brought into North America as a forage grass capable of surviving in hot, dry climates. It is native to Africa, tropical Asia and some other countries in the Old World. This grass spreads along roadsides and thence into native desert communities, and the threat it poses, apart from consuming scarce soil and water resources, crowding out, and preventing seedling establishment of natives, is that it burns easily. Such fires also kill the native desert vegetation, which has never had to deal with fire and so has no protection against it. Apparently buffelgrass only lasts for a decade or so, after which it has exhausted soil resources, leaving behind a waste land. Whether that waste land will ever regenerate with native desert vegetation remains to be seen, but I wouldn’t want to hold my breath, or take the risk.
As a keystone species, if ironwood becomes scarce, or extinct, it will take other desert vegetation down with it. Its own attributes, slow growth and difficult seedling establishment, both adaptations to desert conditions, don’t help it in this new situation, brought about within a couple of decades by the hand of agricultural man.
Ask yourselves: do you really want to see the iconic, unique vegetation of the Sonoran desert (and elsewhere) disappear as the result of a rampant invasive that is not controlled? Remember, for those of you who live in an exclusively anthropocentric world, there is an economic aspect to this too: thousands of tourists visit the Sonoran every year. If your answer is no, you would like to see desert vegetation preserved, then had you better not stop castigating the people you scornfully call “nativists” who go out, working for hours in the hot sun, many without financial compensation, pulling or herbiciding this invasive (it is of course no respecter of national park boundaries)?
Webmaster: Buffelgrass is only one of the problems for ironwood. In the short run, the herbicides being used to kill buffelgrass are probably as much of a threat to ironwood as the buffelgrass itself. Herbicides damage the roots of trees and they damage the soil by killing the microbes and fungi needed by plants. In the long run, climate change is likely the greatest threat to ironwood as heat and drought intensify in the desert. Your desire to protect nature would be better served by focusing on the causes of climate change, such as needlessly destroying healthy trees storing carbon.
Also ask yourselves why most professional ecologists are in favour of conservation and restoration and why such activities get the backing of international agencies such as the IUCN (International Union for the Conservation of Nature). May you not be missing something here? They see the big picture of the destruction of natural communities, not by herbicides, but by population expansion, agriculture, commercialism, over-consumption both by affluent societies and by impoverished, subsistence ones, the loss of nature before it has even been discovered and understood. It is easy for your commentators to say, oh, herbicides are bad, non-natives are good, they’re pretty, they bloom longer than the natives do, why should anyone tell me what I should plant in my garden, etc. But they need to understand the bigger picture.
Webmaster: You ask why most professional ecologists are in favor of “restoration?” Because they are earning a living on those projects. Nothing is a more powerful motivator than our economic interests. None of the critics you see here on Million Trees are being paid to be critics of nativism in nature.
As to the evolutionary trajectory argument, no, none of us can predict the future (except perhaps that an awfully high percentage of species are on a trajectory of extinction, and the populations of many others will decline), but some of us believe that the world isn’t all about what humans want; it’s a world we share with millions of other species which should have a chance to pursue their evolutionary destinies, whatever they are, without undue human influence.
Webmaster: More misanthropy.
I think your blog provides a great disservice to nature and to human society in general, by promulgating biased ideas and encouraging further anthropocentrism rather than an understanding of ecology. I see from your vehemence and passion that you think you are fighting a losing battle, but believe me, it is nature – and “nativists” – who are losing the battle in the age of the Anthropocene.
See http://www.desertmuseum.org/invaders/invaders_buffelgrass.php
Webmaster: The “passion” seems to come from you and your colleagues. Here on Million Trees, we just methodically plow through the obfuscation that supports the “restoration” industry. And we will continue to do so as long as nativists continue damaging our public lands and exposing us to dangerous pesticides.
We are done here. I have reached my limit of self-righteous scolding.
We DO “understand the bigger picture.” Patricia, you make so many patronizing assumptions without knowing us. You assume I’m for over-population? I think humans should stop reproducing until we are back to a number that does not harm the environment.
Of course I eat organic though living below the poverty line. I limit grains I eat and would never knowingly eat toxic canola oil. I disagree with agriculture completely. Mono-culture is destroying the earth. And there is no need for factory farms feeding animals GMO grains and soy that they would never choose. Cattle should be pastured, eating the plants and small animals that they evolved to eat. (Insects and molluscs are animals.)
Of course the “experts” making money off nativism are incredibly biased.
Million Trees answered you beautifully, but I had to add that from what I’ve seen of nativists, they are an extremely privileged and biased group who often does not seem to actually care about the environment and the plants and animals, except for a select few. Of course I don’t want any species to die out, but, in seeing “the bigger picture,” I’m also concerned for the individual plants and animals who I believe think and feel. No one is “forcing” native species to use non-native plants. They are choosing them and I believe are far wiser than we are about what they need and want. They adapt and appreciate when an exotic plant is more nutritious or protective than native plants and take advantage of them. Do you really think anyone is forcing eagles, hawks and large owls to prefer Eucalyptus for nesting? Or Monarch butterflies preferring Eucalyptus? The problem is interfering humans wanting to destroy their new habitats.
I think nativists should remove themselves and stop being hypocritical. How many have gardens with non-native ornamentals and vegetables, fruit trees, etc?
“Does no-one understand the value of a natural community of native plants, its beauty and adaptability, its role in a complete ecosystem, its value for scientific understanding, its right to exist, its ultimate benefit to humanity?”
[Do you not] understand the value of a natural community [with a mix] of native [and non-native] plants, its beauty and adaptability, its role in a complete ecosystem, its value for scientific understanding, its right to exist, its ultimate benefit to humanity? If not, it’s only because of blindness caused by narrow ideology.
I can find common cause with the commentator who said she is against over-population, an expanding economy, etc., eats organic and hates “killing things.” (Although even if you are an organic vegan you have to kill things – only plants are autotrophs, self-feeding, through the process of photosynthesis – the rest of us animals have to eat plants and animals that were formerly alive in order to live.) But I agree that killing one organism to save another (say, a native) raises a huge ethical dilemma, after all they are all innocents, just doing what they are programmed to do by their DNA to live and thrive. This is why I am in favour of getting rid of invasives while they exist in low populations – to reduce the amount of killing that has to be done. Playing God isn’t pleasant, so that is why I am also in favour of humankind taking more of a backseat, retracting our footprint, giving nature more space, and not contributing to past mistakes by growing things in our gardens that could become potentially invasive!
I am not a vegan. All animals have to eat someone to live and humans are omnivores.
Please, if you want to get rid of invasive non-natives, start with yourself. And do stop “playing god.”
Please learn from the native animals who need and treasure the exotic plants. Realize everything has changed and recognize that the nativist’s (primarily a very privileged non-native group) agenda is set on destroying hundreds of thousands of trees which now are the most suited to our increasingly hot environment. They are promoting catastrophic fire with the treeless environment they demand.
So much of what is being considered “invasive” is about making money for someone. Relatively rare plants are on the list. We need more diversity, not less.
I really recommend reading through this blog and learning. I also recommend reading on facebook, the postings of https://www.facebook.com/savetheeastbayhills/?fref=ts