With the Qixi Festival only two days away, online sales of fireflies, an illuminating symbol of love, have surged to the dismay of insect experts.

"Usually we sell hundreds of fireflies every day, but the sales volume increases significantly about a week before Qixi," said Li Ting, a storeowner of Taobao, a Chinese online marketplace. She added that she sold 2,000 to 3,000 fireflies per day this week.

"We have sold 20,000 already this month," she said.

According to Li, fireflies as gifts are most popular in Shanghai and Beijing, and in Zhejiang and Guangdong provinces.

Nearly three quarters of the firefly buyers are male white-collar workers younger than 30 years old, recent statistics from taobao.com show.

"I'd buy my girlfriend a few if she likes fireflies. A 5-yuan (80-cent) bug isn't an expensive way to strike a romantic note," said Xie Chaoyang, a 22-year-old student from Shanghai's East China Normal University.

Data also show that August, when the traditional romance day in China falls this year, is the peak season for firefly sales. "That's mainly because fireflies couldn't survive on the West's Valentine's Day, in February," Li said. She also said lighting bugs are considered an unusual gift among young people, as the bug has been associated with love since ancient China.

But although tiny lighting bugs add romantic ambience for couples in love, they're not easy to transport and feed, firefly expert Fu Xinhua said.

"Many suppliers claim they breed lighting bugs in captivity, but the fact is, more than 99 percent of them catch the bugs in the wild due to the low cost," said Fu, who teaches entomology at Wuhan's Huazhong Agricultural University and spends seven months every year on firefly research in the field.

"Moreover, up to 50 percent of the fireflies may die on their way to create human romance," Fu added.

Chen Yu, another online shopkeeper from taobao.com, said that 400 fireflies she once shipped all died before they reached her customers because of the heat in the postal parcels.

Li's bug supply came from a firefly farm in Ganzhou, Jiangxi province. The farm's owner, He Jianming, acknowledged the difficulty of transporting fireflies, especially during summer.

"They easily die in hot weather," he said. "We have to send the fireflies to customers by air-conditioned buses in summer instead of by express delivery, as at least 20 percent of the fireflies could die on the way."

He said that in order to keep the firefly cost to 2 yuan each, he built his farm outdoors. "The usual cost of breeding fireflies is around 8 to 20 yuan each — far more expensive than the price you could find online," said He.

Fu said selling fireflies online is the wrong way to develop the mainland's firefly industry chain, and contrasts with tourism-oriented firefly protection zones in Japan, Malaysia and Thailand.

"Many may argue that after the romantic moment, they could let the firefly go into the wild, but that would bring another problem — a biological invasion. If you place the lighting bugs somewhere other than their own environments, similar local species could be threatened," said Fu.

He added that in the wild, fireflies have a life span of 10 to 14 days, while they can survive for only two to five days if bought online because of the injuries the insects suffer from capture and transportation.

"I don't think it makes sense to connect the lighting bugs with Qixi simply because the primary purpose of light in adult beetles is to be used for mate selection," Fu added.

The first firefly park in the mainland opened in Fujian province's Xiamen in 2010. It has more than 10,000 fireflies in a wetland valley that is a favorable ecological environment for the bug. More than 10,000 people have visited the park, which only opens in summer — the best time of the year to observe the insect.

Ma Yiyun contributed to this story.

Contact the writer at shiyingying@chinadaily.com.cn