A man stands in the street holding a banner. It reads: "Wanted: Flies".

Guo Zhanqi, a 61-year-old farmer from Heibei Province, can be seen most days in parks and other popular spots around Beijing, buying flies at 2 yuan apiece from whoever has them to sell.

The reason is that Guo and his friend Ji Guijun plan to kill 80 percent of the insects in Beijing ahead of next year's Olympics.

The two men began collecting flies in Beijing and neighboring cities last year and have since spent more than 2,000 yuan (US$265) on them.

To find the best way to kill them, Ji bought a video camera and has recorded hours of footage showing the life of flies, from mating to egg laying and all stages of their development.

He also collected hundreds of fly eggs and eggshells to aid his research.

Public toilets are hotbeds for fly reproduction and disease, Ji said.

"The toilets within the Third Ring Road are more or less OK, but it's a totally different picture if you outside the Fifth Ring Road," the 48-year-old said.

"We are looking to eliminate the main centers of fly reproduction by early spring and then build new toilets."

Ji has submitted plans for his invention, the 'ecological toilet', to the State Intellectual Property Office to apply for a patent.

However, experts in the capital say the fly situation has been improving every year.

"We are not worried about the problem because we are making efforts to control it and the measures are workable," Zeng Xiaopeng, director of the Beijing Center for Disease Control and Prevention told China Daily.

The way to eradicate the fly problem is to control the places where they reproduce, he said.

The municipal government has improved the management of the city's waste and toilets, and has introduced anti-fly facilities in places where they are most prevalent, he said.

In April, the two farmers wrote to the 2008 Beijing Olympic Games organizing committee, expressing their hope to become volunteers supervising the toilets.

"We expect the Olympic Games will be glorious, and without a single fly," Guo said.

(China Daily August 25, 2007)