Many birds are from China's southern areas like Hainan and Yunnan provinces and most of them are exotic to north China with fancy names, like the seven-color, high crest, red coral and ribbon.

Local birds are also an important work force in the campaign, like yellowbirds, skylarks and crossbills.

Organizers of the project approved the work of these guest birds, saying that with their help, no signs of pests were spotted.

This is just one of the biological methods employed by Beijing Botanic Garden against pests, and other pest catchers involved ladybird beetles, mantises and aphid lions.

The Botanic Garden claims to have replaced all chemical pesticides with biological controls.

(Xinhua News Agency June 19, 2002)