How Fireflies Are Keeping This Tiny Mexican Town Alive

for National Geographic

AS NIGHT FALLS on Laguna Azul, an ecotourism lodge on the outskirts of the Mexican hamlet of Nanacamilpa, it looks like rain, and a group of eight tourists nervously watch the sky. Their guides look unconcerned. Cold rain makes for a miserable walk, but the fireflies love it.

A younger guide introduces himself in a strong voice as an older one looks on, leaning on a thick walking stick. The guide lists the basic rules of the tour: walk only on the path, no wandering, no music, no alcohol, no insect repellent, no lamps, and absolutely no cell phones. Any light, even that of a cell phone display, can distract the fireflies.

The walk follows sprawling farmland up a hill to the very edge of the forest. The guides pass fields of wheat, barley, fava beans, and corn before stopping for a moment. They explain that the corn fields to our right are a native corn that doesn’t require pesticides. The hybrid corn to our left, abutting the forest, requires regular spraying.

In the forest we see pines, oaks, and a fir called oyamel. The crowd bunches and murmurs. Several children look bored and start to squirm. Then it begins, slowly—a blink here, a flash there. When the dusk fades, the fireflies come out in earnest.

Individually they are yellow points of light wandering crooked paths, rhythmically blinking. As a whole they are a swirling mass of light, like fairies just out of reach. The guides asked for silence but no one listened, especially the kids, who are squealing and talking excitedly.

After about an hour the show hits its climax, with thousands of fireflies swirling and lighting up almost in unison. The younger guide motions to us, and we silently step away from the group. Away from the starstruck kids, the fireflies come even closer, zipping past our faces in a desperate search for mates. Then, as gradually as it started, the show ends and the swarm dwindles to a few flashing fireflies.

With a projected 100,000 visitors from mid-June to mid-August, Nanacamilpa and its fireflies are fast becoming a national treasure and a lucrative source of cash for a chronically poor region. It wasn’t always like this. Just five years ago there were no firefly tourists here, and indeed the fireflies themselves were unknown to science. The explosion of interest in the nocturnal light shows has thrilled some and worried others, as scientists scramble to understand these insects and authorities puzzle over how to protect the goose that lays the golden egg.

After about an hour the show hits its climax, with thousands of fireflies swirling and lighting up almost in unison. The younger guide motions to us, and we silently step away from the group. Away from the starstruck kids, the fireflies come even closer, zipping past our faces in a desperate search for mates. Then, as gradually as it started, the show ends and the swarm dwindles to a few flashing fireflies.

With a projected 100,000 visitors from mid-June to mid-August, Nanacamilpa and its fireflies are fast becoming a national treasure and a lucrative source of cash for a chronically poor region. It wasn’t always like this. Just five years ago there were no firefly tourists here, and indeed the fireflies themselves were unknown to science. The explosion of interest in the nocturnal light shows has thrilled some and worried others, as scientists scramble to understand these insects and authorities puzzle over how to protect the goose that lays the golden egg.

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