We left Wuhan, China, late one afternoon, crossing the Yangtze River and driving south for hours. As darkness fell, we joined the crowd that spilled out from five massive tour buses. Over 400 city dwellers—young couples, grandparents, families with kids—had traveled for hours into the countryside to watch the sparkling courtship of bioluminescent beetles. Our host, Xinhua Fu, an entomologist at Huazhong Agricultural University in Wuhan and an expert on Chinese fireflies, quickly ushered the eager group onto a dirt track that snaked between rice fields.

As mist gathered between folds of distant hills, we saw the first glimmering fireflies. Chattering children hushed. Adults murmured quietly to one another in mesmerized delight. Fu pointed out the distinct flash patterns coming from different species, quickly reeling off their scientific names: Abscondita terminalis, A. chinensis, Aquatica ficta. Later the crowd headed back to the buses, illuminated by a rising half moon and still glowing with wonder. No one realized the lights they’d left behind would soon be dancing toward darkness.

Imbued with ancient wisdom, abundant biodiversity and growing technological expertise, the People’s Republic of China is also undergoing a startling metamorphosis. During the past 35 years nearly 500 million people have moved from rural areas into cities. Hemmed in on all sides and estranged from nature, these new city dwellers show symptoms of a pervasive modern affliction: nature nostalgia. But they’ve got money to spend and, for them, nature has become a commodity.

China is home to about 100 known firefly species in 21 genera, with perhaps 100 others yet to be discovered. Spread across the country like a vast and sparkling tapestry, China’s lightning bugs could surely be considered a national treasure. Yet skyrocketing demand for live specimens is driving a lucrative trade that now threatens their survival. In recent years Chinese urbanites have flocked to theme parks for massive firefly shows, and alarming numbers of the insects have become romantic gifts. According to the Firefly Ecological Alliance (FEA), a Chengdu-based conservation organization, over 17 million live fireflies were purchased in 2016. Most were sold through Taobao, the popular online shopping platform, where one vendor reportedly sold as many as 200,000 per day.

What happens to all those insects? Many die for romance—although, sadly, it’s not their own. Live fireflies first appeared on Taobao around 2009, where they gained popularity as wedding decorations. Soon millions were sold to light up birthday, engagement and anniversary celebrations, too. And demand for the gleaming critters skyrockets each August around Qixi Festival, also known as Chinese Valentine’s Day. Instead of elegant roses or fine chocolates, why not give a jar of live fireflies to kindle your beloved’s passion? In 2016 nearly 50 Taobao vendors were marketing lightning bugs as a trendy way to show romance. Some offered jars of 30 live fireflies for 88 yuan (around 45 cents per insect) whereas wholesalers advertised packages of 100,000 for only 0.8 yuan (12 cents) per bug. In a Changzhou park during last year’s Qixi Festival one young man proposed to his girlfriend by buying and releasing nearly a thousand of the creatures.

Although buyers bask in their luminous glow, such prolific commerce spells doom for China’s fireflies. Although these insects spend up to two years as larvae, flying adults last for just two weeks. Of those sold online, an estimated one quarter to one half will die in transit. And those that do reach their destination alive are unlikely to reproduce, due to unsuitable conditions for mating and egg-laying.

Live firefly shows also spur demand. Gigantic nature theme parks and indoor amusement centers have sprouted up all over China. During summer months they attract customers by staging massive—and crowd-pleasing—exhibitions. East Lake Peony Garden in Wuhan was one of the first to host such an event; on opening day in 2015 more than 10,000 visitors came to view a “glow show” featuring thousands of imported fireflies. During summer 2016 theme parks located in more than 70 Chinese cities held hundreds of similar exhibitions. According to Fu, exhibit organizers typically purchase 20,000 insects for a weekend show, at a cost of 1 to 1.2 yuan (15 to 18 cents) per bug. The FEA estimates that such enterprises collectively purchased six million fireflies during 2016.

Where do all these fireflies come from? Theme park operators purchase them from wholesalers who insist their fireflies are bred in specialized “firefly farms.” Taobao vendors, too, often tout their insects as being “captive-bred.” Yet no one has ever seen such farms. Breeding fireflies is difficult and labor-intensive, due to their lengthy larval stage and high mortality rate. This makes it prohibitively expensive, with estimated costs of 10 to 20 yuan ($1.50 to $3) per captive-bred firefly. Given that Taobao vendors sell fireflies online at 1 to 4 yuan each, it seems doubtful that they hail from firefly farms.

Alarmingly, all evidence points to a well-established supply chain that relies on harvesting massive numbers of fireflies from wild populations. Investigations by news media and conservation groups have revealed the insects are harvested mainly from Ganzhou, Jiangxi Province; Tunchang County, Hainan Province; and Xishuangbanna, Yunnan Province. During mating season rural villagers collect wild fireflies from the countryside, selling them for 0.3 to 1 yuan each. Without any regulation, vendors can lie about selling “captive-bred” specimens, and most customers simply lack the motivation to probe more deeply.

Such large-scale harvesting is calamitous for China’s wild populations. Most species have highly specific habitat requirements and limited ranges. Collecting so many reproductive adults from the same place, year after year, will quickly deplete even the most prolific species. As for China’s rarest fireflies, they may already be gone. With harvest rates of 17 million per year, it won’t take long before the lights of China’s bioluminescent denizens are extinguished forever.

But grassroots conservation efforts promise a brighter future. In China, as in most countries, fireflies enjoy no legal protection, so it’s difficult to halt commercial harvesting. Although fueled by urban nostalgia for the natural world, most people are probably oblivious to the ecological damage this trade inflicts. So educational outreach is a top priority for conservation. Since 2015 the FEA has also enlisted volunteers, the news media and local government to protest against commercial firefly shows, and many have been canceled. In 2017, for instance, the shows at Wuhan’s East Lake Peony Garden began using laser lights instead of real insects. And in May 2017, just one day after receiving an appeal from the FEA, the online shopping platform Taobao banned all sales of live fireflies. At the same time, conservation organizations are working to identify and protect natural areas where the illuminated beetles thrive, and encouraging people to enjoy them in their natural habitats.

Worldwide, humans have already ushered innumerable creatures into extinction. We cannot preserve every species, yet surely we can preserve some. Maybe we should pause momentarily to consider: do we really want our children and grandchildren to live in a world devoid of fireflies? Then let’s get busy protecting them before it’s too late.