Ophiocordyceps sinensis is a fungus that parasitizes larvae of ghost moths and produces a fruiting body valued as a herbal remedy. The fungus germinates in the living larva, kills and mummifies it, and then the stalk-like fruiting body emerges from the corpse. It is known in English colloquially as caterpillar fungus, or by its more prominent foreign names (see below): Yartsa Gunbu (Tibetanདབྱར་རྩྭ་དགུན་འབུ་Wyliedbyar rtswa dgun ‘bu, literally “winter worm, summer grass”), or Dōng chóng xià cǎo (Chinese冬虫夏草). Of the various entomopathogenic fungi, Ophiocordyceps sinensis is one that has been used for at least 2000 years[2] for its reputed abilities to treat many diseases related to lungs, kidney, and erectile dysfunction. This fungus is not yet cultivated commercially,[3] despite the fact that several fermentable strains of Ophiocordyceps sinensis have been isolated by Chinese scientists.[4] Overharvesting and over exploitation have led to the classification of O. sinensis as an endangered species in China.[5]Additional research needs to be carried out in order to understand its morphology and growth habit for conservation and optimum utilization.