Yarsagumba is a hybrid between an insect and a fungus. In early spring, after having spent the winter underground, the caterpillar Thitarodes emerges to eat. This is when the Ophiocordyceps Sinensis, a powerful endoparasite, strikes its host. It invades its body by taking control of its immune system, kills it and grows out of its head. This organism is known across the West as cordyceps, as pinyin in China, and as yarsagumba in Nepal and Tibet, which literally translates as “worm in the winter, grass in the summer”.