Which fungus is commonly called the caterpillar fungus?

The fungus commonly called the caterpillar fungus is Ophiocordyceps sinensis.

This entomopathogenic fungus infects larvae of ghost moths and related moths living underground in alpine grasslands. It eventually kills and mummifies the larva, then sends a dark, stalk-like fruiting body from the insect’s head above the soil.

Ophiocordyceps sinensis is associated mainly with the Tibetan Plateau and Himalayan regions, generally at elevations above 3,000 metres. In Tibet it is called yartsa gunbu, meaning “summer grass, winter worm”; the Chinese name dong chong xia cao expresses the same transformation.

The species was scientifically described in 1843 as Sphaeria sinensis. Molecular and taxonomic work transferred it from Cordyceps to Ophiocordyceps in 2007, so Cordyceps sinensis remains a familiar synonym. Wild specimens are prized in traditional medicine, but overharvesting, heavy-metal contamination and uncertain medicinal benefits are important cautions.