It's the world's most rare and expensive herb - a mysterious aphrodisiac which only grows on the head of caterpillars in Himalayas. But trade in yarchagumba is funding the Maoist uprising. The best Yarchagumba comes from Dolpa - the poorest region of Nepal, where there are no roads, few jobs - an area dependent on aid. At harvest time, entire villages empty as inhabitants go in search of the herb. "Everybody wants to collect yarchagumba to earn money." But Maoists have taken over the trade and impose their own tax, staving the government of it's income. "We make a lot of money from the yarchagumba tax. It's the main source of income for our party", states Maoist spokesman Comrade Deepak.