Abstract: A new pollination mechanism is reported of an orchid species, Bulbophyllum penicillium, based on a field observation in Southeast Yunnan of China. This species has a sensitive lip, and there is a distance of 2–3 mm between it and column apex. Once the lip is touched by a landing insect, it will move up and down or swing left and right continuously, just like a moving caterpillar. By suck a lip movement, the pollinator, a very small fruit fly (Drosophila sp.) ca. 1 mm in height, will be pressed toward the column apex where anther and stigma are located, and then cross-pollination takes place. This unique mode of pollination, depending on the movement of lip rather than insect itself, has never been found before in either Orchidaceae or other families of angiosperms.

Key words: pollination mechanism, Bulbophyllum penicillium, Drosophila, lip movement.