High up in the mountains of the Tibetan plateau, nomads crawl on their hands and knees searching for a rather gruesome, but very valuable, parasitical fungus. Ophiocordyceps sinensis germinates in living moth larvae, killing and mummifying them, and then growing a stalk-like fruiting body out of its head.

Commonly known as caterpillar fungus, it is prized in traditional Chinese and Tibetan medicine. The fungus can supposedly be used to treat a wide range of ailments, including asthma, cancer and erectile dysfunction. It is considered as having a balance of yin and yang as it is apparently both animal and vegetable.

Award-winning Getty Images photojournalist Kevin Frayer travelled to the Tibetan Plateau to document the search for the caterpillar fungus.

cordyceps Tibet caterpillar fungus
Tibetan nomads crawl on their knees on a hillside at high altitude as they search for cordycep fungusKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan nomad crawls while harvesting cordycep fungus near Sershul on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan nomad swings a pick as he searches for cordycep fungus at high altitude on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan nomads and traders examine cordycep fungus for sale at a market in YushuKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan nomad women clean cordycep fungus at a market in Yushu on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan woman displays high quality cordycep fungus at a market in Yushu on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan nomad lays out his cleaned cordycep fungus for sale at a market in SershulKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan inspects high quality cordycep fungus at a market in YushuKevin Frayer/Getty Images

Frayer told IBTimes UK: "I have travelled often to the Tibetan plateau but this was the first time I was able to see the cordyceps harvest. It's such a short season yet so crucial to the local economy for Tibetans. It's not a traditional way of life for them and a somewhat recent phenomenon fuelled by outrageous demand as a medicine in China. Even though the value of cordyceps is declining a bit, the local people can make enough money for the entire year."

He added: "The harvesting happens at altitudes mostly above 4,500m. The most valuable cordyceps are often in the most arduous places to reach and it's not easy." Environmentalists increasingly warn that overharvesting of caterpillar fungus carries the cost of degradation to mountain grasslands that are essential for yak and cattle grazing.

The demand has created a booming economy for what Tibetans call yartsa gunbu, or summer grass, winter worm (ie, it is a worm in winter and a grass in summer). Top quality, large caterpillar fungus can sell for around $10 (£7) each, or £35,000 per pound. Tibetans who rely primarily on farming and herding have turned to the weeks-long harvest as a means of earning income to last through the year. The annual gold rush has transformed parts of rural Tibetan areas, generating about 40% of the local economy.

cordyceps Tibet caterpillar fungus
A Tibetan nomad laughs as vendors buy and sell cordycep fungus at a market in SershulKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan nomad counts money after selling his cordycep fungus at a market in YushuKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Chinese vendors and Tibetan nomads buy and sell cordycep fungus at a market in SershuKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan nomad boy watches as vendors buy and sell cordycep fungus at a market in SershulKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Traders and Tibetan nomads crowd around as they bid on cordycep fungus for sale at a market in YushuKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan nomads buy and sell cordycep fungus at a market in SershulKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Chinese traders examine and sort cordycep fungus at a marketKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan nomads and traders examine cordycep fungus at a market in YushuKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan nomads check cordycep fungus as another tries to sell his horse in SershulKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tents used by Tibetan nomads picking cordycep fungus are seen on the night of the full moon near Yushu on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A young Tibetan nomad girl holds her sister at a temporary camp for cordycep fungus pickers near SershulKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan woman holds a baby as she stands outside a tent at a temporary camp for cordycep pickers near Zadoi in the Yushu Tibetan Autonomous PrefectureKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A young Tibetan nomad girl rests on a motorcycle at a temporary camp for cordycep fungus pickers near SershulKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan nomads play after a day of working at a temporary camp for picking cordycep fungusKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Five members of a Tibetan nomad family crowd on to a motorcycle at a camp for cordycep pickers near SershulKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan children sit on a mattress in a tent at a temporary camp for cordycep pickers near Zadoi on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A young Tibetan child from a poor family sits in a tent at a temporary camp for cordycep pickers near ZadoiKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan nomad checks a fake gold cap that he had put on a tooth by a street dentist during a break from harvesting cordycep fungus at the Sershul Monastery on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan baby lies in a tent at a temporary camp for cordycep pickers near Zadoi on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan man throws prayers in the air at a high altitude pass on the Tibetan Plateau near YushuKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan nomads stand amongst prayer flags placed at their camp for picking cordycep fungusKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan nomad child walks at a temporary camp for cordycep harvesters near Sershul after a fresh snowfallKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan man walks with his sons at high altitude after picking cordycep fungus near ZadoiKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan Buddhist monks debate outside the Sershul Monastery on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan monks walk with their horses walk in fresh snow near Sershul on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan monk walks with a friend during a break from harvesting cordycep fungus at the Sershul Monastery on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A young Tibetan monk walks on a road near Sershul, an area well known for cordycep harvestingKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
Tibetan nomads walk at the Sershul Monastery on the 15th day of Saka Dawa, the holiest day of the Buddhist calendar, when harvesting is prohibitedKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
A Tibetan nomad couple laugh together while harvesting cordycep fungus near Sershul on the Tibetan PlateauKevin Frayer/Getty Images
cordyceps Tibet caterpillar fungus
An aerial photo of the mountains and grasslands of the Tibetan PlateauKevin Frayer/Getty Images

Frayer told IBTimes UK: "The most worrying part of this somewhat strange industry is that many Tibetan nomads are choosing this as an alternative to the traditional life of herding yaks and other livestock, hedging everything on the fungus. In many ways it is a big gamble, and I suppose in the process traditions and self-sufficiencies can be lost."