Nature & Climate

Pests? Pets? How Language Changes Our Perception of Animals

In a world of declining biodiversity, dismissing creatures as nuisances is becoming unsustainable

7 min read

Pigeon walking down the street
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My neatnik grandmother’s rule of thumb when it came to insects was that a spider in the home meant good luck, but she would have killed the primeval bug in my sink without batting an eye. Pinkie-sized, too many legs, and lethal-looking feelers–I grabbed a paper towel and was about to squish it when I paused. Wait. Sure, it looked like a miniature stand-in for a B-movie alien, and it was in my clean kitchen, but it wasn’t going anywhere. It wasn’t a threat. In this day of species decline, who was I to kill this critter?

There’s a boundary between what’s acceptable inside our walls and what belongs outside. Like most people, I like to think that I can choose which guests come into my home, and that includes all manner of animal. It makes sense to protect our food against hungry nonhuman mouths, and to protect humans and livestock against attack, even if the threat is just a mosquito. It’s also true that species can slide from being deemed a “good animal” to being a “bad pest.” Crickets are cherished pets in some parts of the world, but they’re bred for bait in others–and woe to any songful cricket that finds itself within the walls of my uncle’s house in Los Angeles.

The profound humanness of cities is what sets them apart from other places. Farmland is deeply controlled nature, shaped for human purposes, and wilderness is an indifferent place in which humans are just another species among many; urban spaces are areas of human control, anthropogenic citadels. By the time a species has entered an urban space, if it hasn’t been specifically classified as desirable, it’s probably considered a nuisance. What do we do with any plant that dares to grow on its own? We call it a weed. We welcome swans and ducks in parks but not pigeons on roof ledges or sparrows and starlings on tabletops.

We hold intense prejudices against many of the species that have the audacity to poop on our buildings or emerge from between sidewalk cracks. We have derogatory names and stories for the urban inhabitants that we don’t like: filthy rats, filthy mice, rats with wings (pigeons and/or bats, depending on the location). Maybe, though, the notion of what constitutes an acceptable urban guest has become too restrictive, too rigid to incorporate a new understanding of the importance of biodiversity in ecosystems–including urban ecosystems. When it comes down to it, we’ve become far too eager to label species as pests; too willing to squish any bug in our path.

So, before making any lethal decisions, I decided to go and look up the bent-legged gray beast in my sink. It was fearsome, the way it reared up and tried to climb the sink walls. I shuddered at the thought that it might have come up through the drain. I found it after a quick internet search: a house centipede. I’ve encountered these pale segmented insects before and always promptly killed them without much thought. A bug is a bug. Also, I’m not a fan of giant centipedes. Still, I hesitated.

Species decline around the world has become common knowledge. If city dwellers have only seen updates on the dwindling numbers of iconic species, like polar bears or tigers, they may think that this is a distant phenomenon, one that doesn’t affect them at all. Humans seem to be in no danger of decline. If city pests like pigeons or seagulls were to die out, would that really be such a bad thing? What about house centipedes?

When was the last time you had a car windshield full of bug splotches? It’s a thoroughly unscientific metric, and not one we can check retroactively without gathering thousands of images of splattered windshields over the decades, but people around the world are noticing that they don’t need to clean their windshields as frequently as in the past. The fact is, we’ve taken abundance for granted. These days, even some of the most common animals are struggling. Flying insect populations are down by an estimated 75 percent in some places. On a city level, urban sparrows are in drastic decline around the world, reduced by 60 percent in certain cities. The population drop is thought to be due to pollution, worsening diets, and poor nesting options. (Many modern buildings lack the ledges and niches that sparrows and other species seek out as homes.) Plus, there’s a lack of invertebrate prey–that is, insects.

Even if you don’t have much interest in an overall decline in biodiversity, take heed: whether you like it or not, city human, you are part of an ecological system. The fact that the highly adaptable urban sparrow isn’t thriving in cities should worry you more than whether they grab crumbs off outdoor tables. Urban-dwelling humans want a clean and controlled environment, but they also take demonstrable comfort in green spaces, in birds, in animal life. Glyn Young, a conservation biologist at the Durrell Wildlife Conservation Trust, in the U.K., works on protecting bird species on the brink of extinction. He points to studies indicating that healthy urban bird populations indicate a livable habitat for humans as well. Perhaps more importantly, understanding biodiversity and our place in an urban ecosystem can offer a deep sense of well-being in stressful times. To put it selfishly, as Young does, the ecosystem services of our fellow species “not only provide many of our basic needs and enhance our safety; they also breathe the fundamental essence into what it means to be a human.”

Do we even know what happens when urban ecosystems fall apart? The biodiversity of plants, animals, and insects is part of what makes urban life habitable for humans. Do we want to find out what a city environment becomes when it is devoid of the animals that have co-evolved to survive its requirements?

In “How Pigeons Became Rats,” Colin Jerolmack describes the species we label as “nuisance animals” as the ones that cross the line between civilization and nature. They are the creatures often associated with the least clean aspects of urban life: sewers, garbage, gutters, and sidewalks. Pigeons offer the perfect example of what can make people uncomfortable. During the course of the 20th century, the city pigeon became a symbol of an urban intruder, nesting and copulating and defecating wherever it wanted, reproducing at alarming rates. Cleaning up a city came to mean purging urban areas of these birds, which were sometimes stand-ins for other undesirable members of society, like the homeless or immigrants. According to Jerolmack, some time before a 1966 New York Times article dubbed pigeons “rats with wings,” the terms “pigeon” and “dove” were interchangeable when it came to the bird itself.

Maybe we could better appreciate the excellent qualities of urban pigeons if, as the National Audubon Society, a U.S. conservation organization, suggests, we were to start calling them by their older name: rock doves. Rock doves prosper in human settlements, and they were popular for millennia as pets and messengers. They survive on flying insects and human refuse. They live in lifelong monogamy, and both parents nurture their young. They’ve long been symbols of peace, and they’re happy to nest in whatever corners are available in human architecture. In an era when so many species are going into the great beyond, shouldn’t we applaud a bird that puts up a fight against all attempts at eradication?

One way of looking at species that we consider pests, says Jeff Ollerton, a biodiversity ecologist at the University of Northampton, is to think of them as “things that people don’t necessarily “‘like’ but which provide an important service (for example, the boss, banks, solicitors).” He points out, “Many “‘pests’ are a necessary evil, playing a role in our urban ecosystems, such as eating other, far more abundant pests (spiders, wasps), or pollinating flowers that produce fruit for birds in the winter (wasps, ivy).”

The notion of “ecosystem services” isn’t something most urban dwellers consider when designating something as a pest. As urban spaces expand in geographic size and population, the habitats around them are absorbed, re-formed for human needs. When we talk about making cities more resilient to climate change by, for example, installing more vertical green spaces in order to cool buildings and streets, we need to accept that, to be truly viable and sustainable, an increase in green spaces demands the ecosystem services of a range of species. Some of those services might be provided by species we currently consider pests.

The strange thing about humans is that the very aspects of anthropogenic adaptation we so admire in ourselves are the ones we condemn in other species. Why do so many urban spaces have pigeons, rats, cockroaches, crows, and spiders? Because those are the tenacious species, the adaptable ones that find a way to make the human ecosystem work for them. They’ve been living alongside us since we built our first cities.

David George Haskell, author of The Songs of Trees and a biologist at The University of the South, in Sewanee, Tennessee, expands on the idea of a “pest” species as tethered to a place and time. A plant like the non-native Asian privet can severely impact native plants in certain areas. Haskell says, “In the future, this species may prove to have a different role. In a post-fossil fuel world where we need to feed ourselves from more local sources, privet is an excellent winter fodder for ruminant animals. Its seeds are also a source of oil.” He doesn’t think, however, that the privet’s “future potential is an argument for letting the plant grow everywhere.” Still, we do ourselves no favors by blindly eradicating species without placing them in a broader context.

Building truly sustainable cities means blurring the line between urban and natural settings. It’s this new, hybrid urban space that will allow us to have cleaner air, for example, or to locally source our food from rooftop gardens. And to do this we need a village of species that can brave our human world. We need species that hang on to life like proverbial weeds.

So how do we determine whether the animal or plant at hand is a pest or a scrappy fellow traveler? For starters, we stop calling them pests. We educate ourselves. We accept that it’s not always convenient to share our habitat, and then we figure out how to do it anyway. We make adjustments. In the American Southwest, for example, we learn to live with urban coyotes by keeping our pets and toddlers indoors at night; in areas with raccoons or bears, we learn to keep our garbage cans tightly shut and inaccessible. We limit our need for control to avoiding true nuisance animals like ticks, and to getting rid of those termites in the baseboards. Less eradication, more accommodation.

We are probably the only animals to classify other species as morally less worthy because they dare to share our space. We need to rebrand pests and, in the process, to re-wild ourselves.

Back to my errant house centipede. Harmless to humans, it is an ancient and intrepid 30-legged hunter of other insects, including cockroaches, silverfish, and termites. Looking at it, I supposed I could reframe it as something other than a very large stinging intruder. I could think of it as an insect-eating dragon. A fierce part of the tapestry of life.

I trapped it and put it outside.

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How We Get To Next was a magazine that explored the future of science, technology, and culture from 2014 to 2019. This article is part of our Nature & Climate section, which looks at how human activity is changing the planet–for better or worse. Click the logo to read more.

Paula Read P.K. Read is a freelance writer and translator with an interdisciplinary background in history and environmental strategy. Her work has appeared in Mother Jones, Undark, HuffPost, Litro, The Feminist Wire, Necessary Fiction, and elsewhere. She blogs at