Yang Zhenwen has spent more than two decades trekking the mountains in Southwest China looking into new species

Editor's note: As protection of the planet's flora, fauna and resources becomes increasingly important, China Daily is publishing a series of stories to illustrate the country's commitment to safeguarding the natural world.

The life of Yang Zhenwen is deeply intertwined with butterflies, so much so that the 47-year-old has three nicknames associated with the winged insects.

The curator of the Butterfly Museum in Jinping county, Yunnan, Yang is sometimes referred to as "the butterfly daddy" because he has traversed the mountains of the province in Southwest China for more than two decades to survey butterfly species and contribute to their conservation.

The passionate enthusiast has accompanied scientists on treks into the mountains in Jinping, and even contributed to the discovery and identification of new butterfly species.

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His museum is home to more than 2,200 butterfly specimens, and is the headquarters for Yang to spread knowledge about the insect and promote awareness of environmental protection.

When he is giving tours to visitors and nature enthusiasts, he becomes "the butterfly encyclopedia".

The moniker "the butterfly guardian" has also been bestowed on Yang for his meticulous care for the delicate insects.

As a special treat for the butterflies, he and his fellow villagers have created a concoction of water, sugar, sticky rice flour and pineapple that they spray around the local trails and on branches in the forest.

Despite his many epithets, Yang considers himself an ordinary guy. "If anything, I think of myself only as a butterfly enthusiast with an everlasting passion for them," he said.

Yang was born and raised in the town of Maandi in Jinping county, which is part of the Honghe Hani and Yi autonomous prefecture, bordering Vietnam.

The town has a mild and humid climate with an average temperature of about 18 C and abundant rainfall all year round. There are more than 2,670 hectares of bamboo that provide the butterflies in the area with plentiful food and ideal breeding grounds.

An extraordinary event occurs in Jinping from May to June each year as an estimated 100 million butterflies burst forth from their chrysalises in the biodiverse county, creating a rare sight known as a butterfly explosion.

"When I was a kid, a mountain path leading to my school was thronged with so many butterflies that I had to wave them aside to make my way forward," said Yang. "Some elderly people in the village said that there were even more butterflies when they were young, but there is no clear record as to when butterflies first emerged here."

The butterfly is a symbol of love in China. In a well-known legend considered the Chinese equivalent of Romeo and Juliet, two star-crossed lovers separated due to pressures from their families, transform into a pair of butterflies and live happily ever after.

In the 1980s, locals in Jinping disliked the abundance of butterflies, fearing they were affecting their crops, and some even sprayed chemicals to curb their population.

"For me, I just thought the scene of butterflies flapping their wings in the breeze was very beautiful," said Yang, who was working at an agricultural facility at the time.

Research shows that the so-called butterfly valley in Maandi township has more than 320 species from 11 of the 12 butterfly families found in China, and the most common species is Stichophthalma, or jungle queen.

"The wings of jungle queen butterflies are golden yellow and interspersed with fish scale patterns. In the bright sunlight, their wings seem to reflect the sunrays and carpet the ground or tree branches with a layer of glittering gold," he said.

The spectacle of the butterfly explosion was largely unknown to the outside world until 1998, when a team of experts from Southwest Forestry University in Kunming, Yunnan, who intended to introduce local bamboo to the 1999 Kunming International Horticultural Exposition, visited there and stumbled across the phenomenon.

"Research into the butterfly explosion began in Jinping, and I was able to dedicate more time and effort to observing them," said Yang.

"Their wings are extremely thin and vulnerable. A single raindrop can weigh 20 or 100 times that of a butterfly's wings, and they can easily break if unfurled when wet," he said.

"So on rainy days, I look under tree leaves to find them resting there. If I want to get a closer look at their size and condition, I can only gently pick their bodies up by the tips of my fingers."

The life cycle of a butterfly includes four stages: egg, larva, pupa and adult, with the duration of each stage varying across different species. "Taking the jungle queen species as an example, they spend the majority of their lifetime as caterpillars or larvae, and die within 15 to 20 days after emerging from chrysalises," said Yang.

While the caterpillars mainly feed on bamboo leaves native in Jinping, adult butterflies absorb nutrients from a variety of liquids such as nectar, juice from rotting fruit and tree sap.

To meet the huge demand created by the sudden burst of butterflies in May and June each year, Yang takes the bottle of his sweet concoction with him when he patrols, spraying along the way. "The juice can extend their life span by five to seven days," he said.

There are four recommended areas for observing butterflies in the valley, but Yang goes further into the wild to carry out his research.

"There was a time in 2018 when I was walking in an expanse of primary forest, and I suddenly saw a bear scratching a tree about 10 meters away from me," he said. "My mind went blank at that moment, and I froze for a few seconds before sprinting back where I came from."

While running from the bear, Yang said he tripped on a fallen tree trunk and passed out.

"When I opened my eyes again, several hours had already passed, and I could only feel that my whole body was icy cold," he said. "After realizing that I was not dead, I made my way back home."

Yang said that he's had his fair share of accidents over the years, but the risk has never dampened his enthusiasm for potentially discovering new species and learning more about butterflies.

This year's butterfly explosion was described as being "only small" by Yang.

"There is a natural cycle of having a year with a large number of butterflies followed by a year with relatively fewer," he said. "This year's butterflies also appeared to be larger in size and very healthy, which I believe lays a solid foundation for next year's production of eggs and larvae."

Yang follows the same routine during the peak butterfly season each year.

"I usually set off from home around 6 am to examine how butterflies wake up from their resting places under leaves, and I don't return until dusk falls after they've laid their eggs," he said.

Countless hours spent in the forest have endowed Yang with a vivid understanding of the role butterflies play in nature.

"Because it is an extremely delicate insect, butterflies can also be as seen as a symbol of the health of the local ecology, and only in a favorable, healthy environment can the spectacle of a butterfly explosion occur," he said.

Yang said that about 90 percent of butterflies are eaten by other insects before they reach the adult stage. "As a result, behind a butterfly explosion is an enormous population of diverse animals. Butterflies not only provide a breathtaking sight for us to enjoy, but also contribute to biodiversity," he added.

To step up the protection of butterflies, Jinping county released a regulation in October 2012, which prohibits actions such as altering the natural state of the water environment, spraying pesticides, indiscriminately cutting down trees or digging up bamboo shoots.

Sun Sen, deputy head of the county, said that habitat destruction, environmental pollution, use of fertilizers and pesticides, global climate change, invasive species and overexploitation of resources are regarded as the major challenges in butterfly conservation.

In addition to the release of the regulation, Sun said the county has stepped up awareness campaigns among the public, cracked down on the illegal collection and trade of butterflies and helped advance scientific research to improve conservation technologies.

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The butterfly valley in Maandi township has been gaining popularity among domestic and foreign tourists, and the residents have set up rural homestays and restaurants to cater to their needs. According to local authorities, more than 2 million tourists have visited since 2010.

Yang Tingcui, who owns a local grocery store and a hostel, said that she is glad of Jinping county's growing popularity and the increasing number of travelers.

"I strive to keep my rooms clean so that tourists can have a good rest here after they've experienced the mountains and the butterfly valley," she said.

Kazuo Unno, chairman of the Society of Scientific Photography in Japan, has been snapping pictures of natural landscapes for decades and has a particular interest in butterflies.

The 76-year-old visited Jinping in late May upon the recommendation of his Chinese tour guide.

"I have traveled to Laos and Thailand in the past and seen how butterflies rest by the riverbank, and I was excited to discover if there were similar sceneries here in China," he said.

Contact the writers at wangxiaoyu@chinadaily.com.cn