Firefly forest light trails

Follow the Light


Welcome to The Overview, a weekly newsletter in which Editor-in-Chief Willow Defebaugh offers an aerial view of the latest events in climate and culture—and how they all fit together.

Photograph by Konrad Wothe / NPL / Minden Pictures

“Come forth into the light of things, let nature be your teacher.”

William Wordsworth

Have you ever wondered how insects navigate the night? Moths in particular fly by what’s known as transverse orientation. They use the moon as a point of navigation, a kind of north star. By holding the moon at a fixed angle in their vision and aligning themselves to it, they are able to travel straight trajectories and discern their way through the darkness.


Unfortunately, the evolution of these insects did not account for artificial lights, which serve as miniature moons that confuse moths’ ability to navigate. Because their eyes are so attuned to light, artificial ones act as super-stimulants, luring them in and leaving them exposed to predators. According to the scientists behind a recent study on insect decline, light pollution is a critical factor: “We strongly believe artificial light at night—in combination with habitat loss, chemical pollution, invasive species, and climate change—is driving insect declines…another important—but often overlooked—bringer of the insect apocalypse.”


On the night of July 26, 2019, approximately 46 million grasshoppers swarmed the city of Las Vegas—a vision that was all-too common that summer, and evocative of a more literal insect apocalypse. In an analysis published this week in Biology Letters, insect ecologists were able to identify light pollution as the cause, using weather radar data to map the descent of the insects on the brightest areas of the city after dusk. Recognized by satellites as the most luminous spot on Earth by a longshot, Las Vegas casts a glow that is detectable from even 200 miles away.


Another study, this one published in Basic & Applied Ecology, found that light pollution is negatively impacting Photuris versicolor and Photinus pyralis—more commonly known as fireflies, which use blinking, bioluminescent lights for courtship and mating. The field experiment found that they were drawn to artificial lights, and less likely to flash for one another in their presence, which might be contributing to their decline.


Fortunately, light is the simplest form of pollution to remedy. It is far easier to turn off a light than it is to clean up most other pollutants. Insect ecologists are not proposing we live in the dark—only that we should be more discerning in how we interact with the light. Brightness curfews, motion-activated lights, LED lights that block out harmful spectrums are all solutions that could help insect populations.


We often focus on biomimicry as a means to emulate natural processes and solutions in human systems, but what about the ways in which we mirror the maladies afflicting our fellow species? What can we learn from our parallel problems? Are the lures of the age of artifice not leading us to our own demise? We have forsaken nature’s knowing for moons of our own making, orienting ourselves around beacons of limitless growth and consumption that we know to be false.


Light has often been used as a symbol for truth and awareness, that which is known. Maybe discernment (our ability to recognize truth) is the answer not only to our literal light pollution, but the figurative kind as well: the truths of our world that have been poisoned and perverted. Maybe the work we are doing now is the most critical work of all, that of realigning ourselves with the truth—letting nature light the way.

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