Ophiocordyceps Sinensis

There are over 680 documented species of the sac fungus genus Ophiocordyceps, and one of the best known of these is Ophiocordyceps sinensis, colloquially known as caterpillar fungus. The fungus is known in Tibetan as yartsa gunbu or yatsa gunbu, and in Chinese as Dōng chóng xià cǎo (Chinese: 冬虫夏草; literally "winter worm, summer grass").

Caterpillar fungi are the result of a parasitic relationship between the fungus and the larva of the ghost moth genus Thitarodes, several species of which live on the Tibetan Plateau (Tibet, Qinghai, West-Sichuan, SW-Gansu & NW Yunnan), and the Himalayas (India, Nepal, Bhutan). The fungus germinates in living organisms (in some cases larvae), kills and mummifies the insect, and then the fungus grows from the body of the insect.

O. sinensis is known in the West as a medicinal mushroom, and its use has a long history in Traditional Chinese medicine as well as Traditional Tibetan medicine. The hand-collected fungus-caterpillar combination is valued by herbalists and as a status symbol; it is used as an aphrodisiac and treatment for ailments such as fatigue and cancer, although such use is mainly based on traditional Chinese medicine and anecdote.

Recent research however seems to indicate a variety of beneficial effects in animal testing, including increased physical endurance through heightened ATP production in rats.