Ophiocordyceps sinensis

Ophiocordyceps sinensis (formerly known as Cordyceps sinensis), known colloquially as caterpillar fungus, is an entomopathogenic fungus (a fungus that grows on insects) in the family Ophiocordycipitaceae. It is mainly found in the meadows above 3,500 metres (11,500 ft) on the Tibetan Plateau in Tibet and the Himalayan regions of Bhutan, India, and Nepal. It parasitizes larvae of ghost moths and produces a fruiting body which is valued in traditional Chinese medicine as an aphrodisiac. Caterpillar fungus contains the compound cordycepin, an adenosine derivative. However, the fruiting bodies harvested in nature usually contain high amounts of arsenic and other heavy metals, so they are potentially toxic and sales have been strictly regulated by China's State Administration for Market Regulation since 2016.

O. sinensis parasitizes the larvae of moths within the family Hepialidae, specifically genera found on the Tibetan Plateau and in the Himalayas, between elevations of 3,000 and 5,000 metres (10,000 and 16,000 ft). The fungus germinates in the living larva, kills and mummifies it, and then a dark brown stalk-like fruiting body which is a few centimeters long emerges from the corpse and stands upright.

O. sinensis is classified as a medicinal mushroom, and its use has a long history in traditional Chinese medicine as well as traditional Tibetan medicine. The hand-collected, intact fungus-caterpillar body is valued by herbalists as medicine, and because of its cost, its use is also a status symbol.

The fruiting bodies of the fungus are not yet cultivated commercially, but the mycelium form can be cultivated in vitro. Overharvesting and overexploitation have led to the classification of O. sinensis as an endangered species in China. Additional research needs to be carried out in order to understand its morphology and growth habits for conservation and optimum utilization.