Yar-tsa Gam-bu or the Chinese caterpillar mushroom (Cordyceps sinensis) is the costliest medicinal herb of the Himalayas. It is an entomophagous fungi, Cordyceps sinensis growing on the caterpillar of a moth of the Genus Hepialus. It is collected at an altitude above 3800m during the month of June when the snow melts and the fruiting body of the fungi just emerges out of the soil from the mouth end of the dead caterpillar. Around 3000-4000 pieces makes one kilogram of produce which costs between INR 2.5 lakh to 10 lakhs depending on the grade of produce, demand and supply. 
The main use seems to be by atheletes as the drug is not detected in dope tests. Just before the London Olympics, the rate was upto INR 10 lakhs/kg in the Kathmandu market in Nepal. The trade route is from Kathmandu to Hongkong and then elsewhere in the world. The produce is found throughout the Himalayas in India, Nepal, Bhutan and also in Yunnan and Sichuan province in China. It is also supposed to be a cure-all herb and is widely used in Chinese and Tibetan medicine.
