Yarchagumba looks like a shriveled brown chile pepper and is coveted as an aphrodisiac and medicinal cure-all. Literally translated as “summer grass, winter worm,” it forms when a parasitic fungus invades the burrowing larva of a ghost moth, transforms the ­vital ­organs into a cobweb-like mess, and then sends up a wispy sprout through the dead ­insect’s head. The grisly process plays out across the Himalayas and the ­Tibetan Plateau but only at the beginning of the monsoon and only on reclining slopes of grasses, shrubs, and milk vetch at the dizzying altitude of 10,000 to 16,500 feet. Thanks to a spike in global demand, mostly by Asian men looking to enhance their virility, a pound of yarcha­gumba now sells for as much as $50,000, more than the price of gold. ­Profits from the fungus have transformed entire ­villages, vexed government regulators, and even helped bankroll a communist insurgency. Nepal’s former Maoist rebels admit that taxing (read: ­extorting) yarchagumba pickers was their main source of income in their decade-long war against the country’s monarchy.