When nature depends on you and me, will you squish the invaders?

September 28 , 2022

You might not be aware of it, but ecologies around the world have spent centuries resisting the arrival of damaging, invasive species, from flies, to rats, to goats (yes, goats). In this week’s issue of The Distance, writer Molly Redden shows us some of the key chapters in the long history of humanity’s defense against the appearance of new creepy crawlers.

Now, here's Molly:

The first “wanted” posters appeared around my neighborhood in August 2021. WARNING, they blared, in oversized red text. Below, a triptych of photos showed a spiny, moth-like creature with two pairs of spotted wings, one a soft pewter, the other a shock of regal crimson.

For anyone tempted to admire the bugs' beauty, the signs hastened to enumerate their crimes: These were members of an invasive species called Spotted Lanternflies; they feed on native plants and crops, leaving them susceptible to disease; they spread easily, thrive almost anywhere, and can lay their eggs on virtually any surface.

“If you see it, step on it!” the poster urged. “Tell your friends and family.”

Most Americans who are familiar with the spotted lanternfly probably learned about them through a similar call to action. Since the invasive species first touched down in Pennsylvania a decade ago, these colorful menaces have made themselves at home in sixteen states, becoming a regular feature in Central Park and hitching rides as far as North Carolina and Indiana. Wherever the bugs appear, they have the potential to wreak havoc on agriculture and permanently alter the local ecology by decimating native plants. So, ecologists, park managers, and conservationists have pursued them with pleas for the general public to carry out summary executions.

“Kill it! Squash it!” wrote Pennsylvania's agricultural department, while New Jersey, where I lived at the time, put up billboards exhorting us to “Join Jersey's Stomp Team.” When a New Yorker tweeted a photo of a specimen she had mangled on a city sidewalk, the NYC Parks Department replied, “You are a civic hero!”

I was skeptical, even after stomping my first few bugs into the pavement, about this strategy of enlisting citizen vigilantes to fight swarms of unwanted pests. Bugs are tiny; even the bright red ones can be hard to spot. More than that, invasive species seemed to me like an inexorable feature of modern, globalized life.

But it turns out that mobilizing ordinary people to stamp out unwanted invaders is a longstanding tool for protecting native habitats.

Today, Alberta, Canada is one of the only places on the planet where humans live and rats do not. It’s a distinction the province earned thanks in part to its government's effort to mass mobilize the public. Brown rats first snuck into North America onboard European ships in the 1700s. And they have become so ubiquitous in rural and urban settlements alike — I'm personally not even capable of imagining a NYC subway tunnel without also picturing a rat scurrying down the tracks — that it seems counterfactual to categorize them as an “invasive” species.

Alberta, though, was spared a rat infestation because of its geographical isolation until the 1950s. That was when the province's agricultural department discovered several teeming colonies on its border with Saskatchewan. Alarmed at the threat that a rat population would pose to the province's crucial agriculture sector — officials estimated that rats could cause eight figures' worth of damage to the region's crops if unchecked — the government sprang into action.

It sprayed roughly 70 tons of rodenticide along its border with Saskatchewan while requiring members of the public to rat-proof their properties and calling on them to squeal to officials whenever they saw a rodent. Because most Albertans had never seen a rat, the government put up World War II-style posters to publicize what rats looked like and to urge civilians to kill them on sight.

Thanks to this collaboration, Alberta slowly overcame new rat populations, from a peak in the 1970s of 50 to 70 infestations on the border every year, to virtually none today. Albertans still spot a few individual rats every year. But in 2020, the province celebrated its 70th year without an established rat population.

New Zealand, which has no native mammals save for a few kinds of bats, has become overrun with rats, weasels, possums, and cats that are threatening the country's incomparable native fauna, like the kiwi and the tuatara, a rare reptilian survivor from the Triassic period. To try to save its native species, the country's top scientist urged ordinary people to rid the country of predatory mammals — and people obliged. Thousands of citizens have learned to trap cats, mice and weasels on their private property. Reporting on the campaign for the New Yorker, Elizabeth Kolbert found that even school children were being instructed on the virtues of exterminating tiny mammals, with blog posts with titles like “Mrs. Tiggy-Winkle, Serial Killer.” Meanwhile, the Department of Conservation launched an aerial campaign to blanket the country's forests and national parks in rodenticide.

There are profound limitations to this approach. Invasive species surround us, from the subway tunnel I can't picture without rats, to the nearby park I can't picture without pigeons (introduced to North America in the 1600s), to the sidewalk cafe I can't imagine without sparrows (deliberately introduced in the 1850s).

Many invasive species are harmless or even beneficial, prompting a group of scientists in 2011 to call on governments and conservationists to abandon pointless efforts to eradicate all but the most harmful alien species and embrace a world that has been permanently changed: “Most human and natural communities now consist both of long-term residents and of new arrivals, and ecosystems are emerging that never existed before,” they wrote. “It is impractical to try to restore ecosystems to some 'rightful' historical state.” Beyond impracticality, some have raised ethical objections to annihilating species that find themselves in new environments through no fault of their own and giving them a stigmatizing label.

Insects, being so small and numerous, can be the most nettlesome invaders to remove. One year after my New Jersey neighbors and I started stomping on spotted lanternflies, they're still everywhere. (Ironically, one reason they have thrived is because we previously added one of their favorite foods to our parks and forests: the tree of heaven, made famous in Betty Smith's 1943 novel “A Tree Grows In Brooklyn.” The tree is native to China and took over the northeast after becoming a popular ornamental among park planners.) “Relying on citizens as vigilante exterminators,” wrote New York Times journalist Anne Barnard, “is proving inadequate.”

Except the best of these undertakings never rely on individual efforts alone. As Alberta proved, the most effective eradication campaigns combine citizen vigilance with large-scale, well-funded government or private conservation efforts. Albertans now lend out their expertise to other cities and regions trying to stamp out their rat problems; so do New Zealanders. The size of the territory from which humans have totally eradicated invasive predators, Kolbert notes, has shot up every decade “by an order of magnitude.” The island of South Georgia no longer teems with rats. The Galapagos are officially goat-free.

Perhaps the most important role an ordinary person can play, Barnard suggested, is to be engaged on the question of what we ought to do, collectively, about the ways in which we have radically altered the environment around us. A single step on a lanternfly could be the first step toward conceiving of how to build a better flytrap.

Molly Redden is a journalist for HuffPost. Previously, she worked for Mother Jones, the Guardian US, and the New Republic.

Questions We're Asking:

• What are other challenges or problems that depend on communal participation to properly address?

• What gradual changes in your environment have you noticed over the course of many years?

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Write us, TheDistance@fundrise.com

More adventures in the world of weird math — and why the weirdness matters

Alex writes:

Earlier this week, mindlessly doomscrolling, I came across a short, silly, puzzle that stopped my digital sleepwalking in its tracks.

It was another case of what, much earlier this year, I dubbed “weird math.” That is, a case of a behavior or a pattern or a little wrinkle in reality where something is objectively, mathematically true… and yet seems to violate most of the basic human intuition we normally rely on for problem solving. So, in today's issue, we consider a truly, fantastically useless problem, and yet one all the more mathematically — dare I say — upsetting. It’s called “the rope around the Earth problem,” and it can be posed like this:

You tie a rope tautly around a basketball. You’re then tasked with resizing the rope so that if you were able to suspend the rope in a perfect circle around the basketball, exactly one foot of space would separate the ball from the rope at all points. How much longer would you need to make the rope to allow for that additional one foot of space?

As it turns out, 6.28 feet.

Now, you repeat the task, but instead of a basketball, you tie the rope tautly in a circle around the Earth (imagine, for the sake of simplicity, the Earth is perfectly uniform and smooth). Then, the same adjustment: you must lengthen the rope so that a foot of space separates it from the Earth at all points. How much rope do you need to add this time?

Intuitively, most people will start thinking through this problem by considering how much more ground needs to be covered to add a one foot buffer between the sphere and the rope at every point on Earth where it passes. You have to add a foot here, in Seattle, and a foot in Zurich! Plus a foot at every point along the Atlantic. And another foot at that point, over the same Atlantic. And then when you come back around, the whole Pacific too!

So how much additional length do you need? Well, 6.28 feet, just like with the basketball.

Of course, as you will have guessed, the explanation for this puzzle is simple in mathematical terms. As you may remember from middle school geometry, a circle’s circumference is equal to 2πr — or two pi, multiplied by the circle’s radius. In this problem, we’re being asked to expand the circle’s radius by one foot, which means we’re increasing the total circumference by the equivalent of “one foot times two pi.” That’s 6.28 feet, rounded. (Here’s a much more in-depth explanation and look at the math.)

But understanding the math isn’t quite the same as fully digesting the math, to the extent that you can, say, picture it. If you’re like me, the amount of rope necessary to add a foot buffer everywhere on Earth feels much larger than 6.28 feet.

But then I thought about it another way: the length necessary to add a foot is fixed, no matter how big the circle you start with. Taking a one foot radius circle of rope and extending it to two feet requires an additional 6.28 feet. From two to three feet is the same. From three to four, the same. From 20 to 21, the same. And from 20,925,722 feet (approximately the radius of the Earth) to 20,925,723… the same. 6.28 feet.

This is another example of why weird math is so important: A lot of problems in life are not intuitive, especially when it comes to math, science, finances, etc., but in many cases, there’s a good chance other people have already thought through them and have covered our blind spots. That’s one of the critical ideas that Magic: The Gathering professional Luis Scott-Vargas discussed with us back in August, on the power of heuristics, or “rules of thumb.” When you can apply a general rule to a problem, you save yourself tons of time and effort from having to solve it again, each time you encounter it.

But aren’t you glad to know it’s always possible to check the math?

Have any other examples of unintuitive ideas — weird math or otherwise — that can lead to important insights?
Let us know! Write to us at TheDistance@fundrise.com.

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The Distance is supported by Fundrise, edited by Alex Slotnick and Helen Chandler, and produced by Katie Valavanis and Brett Wilson, with help from Motasem Halawani. Our design director is Erin Culliney.