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.

"We are going to get married next year!" a couple shouts through a loudspeaker at a celebration activity on Sunday for the upcoming Qixi Festival in Chongqing. Qixi Festival, a traditional day of romance in China, falls on the seventh day of the seventh lunar month, and this year it falls on Thursday.

"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.