Opinion by Kip Hansen — 24 September 2022
The marvelous mysterious Monarch Butterfly has been getting too much of the wrong type of help in California. Honestly, this does not surprise me, having been born, raised and educated there. The state of California, whose state flag bears the words “California Republic”, has been slipping off the left edge of the political spectrum since the 1960s and like all things on slippery slopes, the state and its politics continue to slide, faster and faster, affecting more and more areas of public and private life.
The latest little bit of madness there is a misguided effort to help the Western Monarch population by the banning the sale of tropical milkweed plants by several counties in the state. Milkweed plants are an absolute necessity for Monarch butterflies to reproduce.
The Western Monarch Migration (see down-page section on the Western Migration) has been seeing a very steep decline over the last couple of decades. There are lots of theories as to the cause, from Global Warming through insecticides and onto the mowing of highway verges – including “all of the above”.
The overwintering population was approaching zero in the winter of 2020-2021 and then, in 2021-2022 skyrocketed with “an over 100-fold increase from the previous year’s total of less than 2,000 monarchs and the highest total since 2016” with the monarch census reporting over 250,000 monarchs in roosts along the California coastline.
Truthfully, neither the sharp decline nor the unbelievable (partial) recovery has been explained to anyone’s satisfaction. It seems unreasonable that a population as small as 2,000 in the spring of 2021 could then produce the 250,000 overwintering Monarchs in a single season. But that is precisely what appears to have happened.
Now we find ourselves — and the Monarchs find themselves — in the summer of 2022 with the environmental activists pitching in to help the California monarchs by banning the sale of tropical milkweeds by nurseries in Marin, Contra Costa, San Mateo and Ventura counties. Why ban the sale of garden plants that monarchs need to reproduce?
Because the California Department of Agriculture recategorized it as a noxious weed. Of course, tropical milkweed is not a weed, and it is not noxious. There is something about the tropical milkweeds that is true however – it is a perennial. That means it does not die off every winter but stays alive and re-greens and blooms the next year, especially in warmer climates like California and the American South. And, because it does not die off, it is possible for these prettier varieties to “host to a protozoan parasite of monarch butterflies (Danaus plexippus) called Ophryocistis electroscirha (OE), which are carried on adult monarchs as they migrate. The dormant OE spores are then deposited on the leaves of the tropical milkweed and infect caterpillars that eat the plant. CDFA (California Department of Food and Agriculture) said that OE infections have been linked to lower migration success, reduction in body mass, lifespan, mating success, and flight ability.” [ source ]
It is not that there is anything special about the tropical milkweeds that is different than the native milkweeds in regards to hosting the protozoan parasites…except that when native milkweed’s tops (above ground portion of the plant) die at the end of the season, the parasites on them die and the next year’s crop of native milkweeds that come up from seed or rhizomes start out not infected – though they soon become so, whereas the tropicals, in mild climates, continue to grow through the warmer winters hosting the protozoans continuously.
So, the whole banning of these beautiful tropical milkweeds and distributing native milkweeds to take their place is based on that little months-long lag.
What do the entomologists (as distinguished from activists) say:
“Arthur Shapiro, a UC Davis professor who has studied monarch butterflies for the past six decades, described the rationale behind the bans as “hogwash.”
“Hugh Dingle, a retired University of California at Davis entomology professor who has studied monarch butterfly migration for more than two decades, said the bans are “basically a wasted effort” and that the focus should be on larger threats such as pesticide and herbicide use. All species of milkweed carry parasites that can affect monarch populations, Dingle said.
“Planting milkweed of any kind in your garden — tropical or native — there’s unlikely to be enough of it to do any good, but it’s not going to do any harm,” Dingle said. “If you like monarchs in your garden, go ahead and plant it. I didn’t want the information on tropical milkweed to cause the ladies of Marin (county) to go running out to their gardens and dig out all of their tropical milkweed because it’s supposedly bad for butterflies. It’s not.”
“David James, an associate entomology professor at Washington State University who has studied monarch butterfly breeding and migration in the [San Francisco] Bay Area, said there is a case to be made about the tropical milkweed as being a vital resource for the monarchs in a changing climate.
“The Monarch is adapting to our warming climate and in doing so a proportion of the population is now spending winters breeding in urban near-coastal California,” James wrote in an email. “And what host plants are there? Some limited native milkweeds but a whole bunch of tropical milkweeds! Taking tropical milkweed away will just make it harder for the population to survive.” [ source for all quotes above]
Say what? California’s entomologists quoted all disagree with the ban and at least one says the ban will have negative, not positive, effects. So where did the idea come from?
“Stephanie Frischie, an agronomist and native plant specialist with the Xerces Society, said there are many purported causes for the decline in monarch butterfly populations. The buildup of pathogens on the tropical milkweed during the winter months is one of these pressures, which can be prevented by having residents plant the readily available native milkweed.
“There is really no single cause and therefore there is no silver bullet to solving monarch decline,” Frischie said. “Where we are right now with current research, there are concerns with tropical milkweed with disease and interrupting migratory behavior. In general, as a conservation organization, we support native plants in their native ranges as habitat for invertebrates.”
The Xerces Society’s concerns have won out in the political battle over the more scientifically based opinions of monarch-specific experts from academia.
Will it make a difference? Will it improve the lot of the Western Migration of Monarchs? Will it harm the migrating population? No one really knows. No one knows because they do not know what — if anything specific — is causing the shifts in that particular segment of the overall population of Western Monarchs.
“The overall population of Western Monarchs?” you might ask. Yes, you see, not all the Monarchs living west of the Rocky Mountains migrate to the coast and overwinter in collective roosts. Many, and no one knows how many monarchs we are talking about, migrate to the urban and suburban neighborhoods along the coast of southern California, continuing to live, breed, and die in their normal pattern and not entering a period of reproductive diapause or forming collective roosts, like their “migrating and overwintering” fellows.
The environmental entomological activists are not trying to save the Western Monarchs, they are trying to save the behavior, the phenomenon, known as the Western Monarch Migration. To the left of the word SUMMER we see the western migration as red and yellow arrows. You can see that some migrate to the same areas in Mexico as the Eastern Monarchs. Others, from the deserts of southern California and western Arizona migrate to and from the southern-most coasts of California and do not form overwintering roosts at all. According to David James (quoted above) some may even just move to coastal Marin County for the winter and carry on living and breeding.
It is mostly those flying down from eastern Washington, eastern Oregon, northern and central California and the western slopes of the Rocky Mountains that form overwintering roosts along the coasts of California, north of Ventura.
It is a matter of opinion as to whether or not the Western Migration is something that must be saved, that must be prevented from disappearing. There is not now, nor has there been in the past, any danger of the Monarchs west of the Rockies going extinct. The only real possibility is that they will cease that particular behavior.
1. Monarch Butterflies are found in many parts of the world, and it is extremely unlikely that they will go extinct.
2. The Monarchs west of the Rockies in the United States are going strong but many of them have ceased the pattern of winter diapause and associated roosting – the phenomenon called the Western Monarch Migration.
3. It is extremely unlikely that the population of monarchs west of the Rockies will go extinct but rather highly possible that the general population will continue to occupy suitable niches in urban and suburban coastal California during the mild California winters and then disperse out into the rest of their western range each Spring, foregoing the diapause stage.
4. Efforts by activist groups to force their human preferences on the Monarchs are not likely to be successful particularly because we do not understand the causes of the changes we are seeing.
5. Finally, the banning of tropical milkweeds is not only unnecessary, but is likely to have the opposite of intended effect, harming the Monarch population instead of helping it.
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Like many other interventions in the past, taking action before understanding the causes of what seem to be undesirable changes in some part of the natural world, this intervention will either fail to improve things or will actually make some things worse. We never seem to learn this lesson.
And while the Xerces Society’s recommendation on this topic has undoubtedly been made in good faith, the California policy setters should have listened to a wider variety of experts from their own universities, those that have studied this particular species, in this particular area and have concerned themselves with this particular phenomenon for decades before recommending any action.
Even time will not tell in this case. There are far too many variables to be able to determine success or failure of this odd little decreed interference in the natural order.
In the end, I ask that you be a Butterfly Friend. Plant butterfly friendly flower gardens, plant milkweeds — yes, preferably but not exclusively, native milkweeds, though even this recommendation depends on where you live — and participate in public meeting that advise state and county road maintenance crews to leave stands of roadside milkweed rather than mowing them.
Thanks for reading.
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via Watts Up With That?
September 24, 2022