Children are useful on the hunt because their sharp eyes allow them to pick the fungus out of the clumps of grass and sodden earth -- a little like finding a needle in a haystack. Although the dead caterpillar is rather unprepossessing in appearance, it's not nearly as disgusting as it sounds: sort of like a little yellow root with a stalk growing out of the top.


"It is very boring work," complains Hiriti, who just this year began fungus-hunting at 10, the same age her mother started.

Reaching into the pocket of her faux leather jacket, the girl pulls out a tissue and unwraps what looks like a 3-inch-long twig, the only piece she found all day. She will sell it for about $3, but it could command a retail price of $10 in Singapore or Tokyo.

"I think people must be insane to pay so much," Lhamotso says. "It's only in the last two years it has gotten so expensive. It's crazy, but it is good for us. How else would I make so much money? I can't read or write."

Lhamotso and the girls expect to make at least $6,000 this season -- about triple what most Chinese families earn in a year. Last year's take was enough that Lhamotso and her husband built their house, the interior wallpapered with photographs from magazines of an assortment of celebrities, movie stars, Mao Tse-tung, the Dalai Lama.

Over a stove burning dung in the center of the main room, Lhamotso boils a kettle of water to make yak-butter tea, a salty brew popular here. The television is the only appliance.

The worm has helped pay for the house, but more important, it has provided the motivation and the money for Hiriti to get an education. The family pays $30 a month in tuition at a Buddhist monastery where Hiriti studies Tibetan, Chinese, a little English and math. (Lhamotso says they can afford tuition for only one child and that her older daughter is needed to help with traditional chores such as milking yaks.)

The caterpillar fungus has made it painfully apparent to Lhamotso and her husband how crippled they are by a lack of education. Neither can speak Chinese or do basic math. So they must rely on intermediaries, many of them Muslim traders, to do the counting, weighing, calculating and marketing of their pickings.

"We need to have one person in the family who is educated," she says.

Lhamotso is well aware that fungus may not be a reliable source of income for much longer. The fungus is growing scarcer each year from over-harvesting and changes in the fragile ecosystem of the Tibetan plateau.

"When I was young, somebody could just walk out of the tent and dig 800 to 900 pieces in a day. Now we have to hike three hours up the mountain and the best we do is maybe 50 pieces," says Tsering, 38, in a straw hat who was picking one afternoon with Lhamotso and her friends.

The bottom could drop out of the market if artificially cultivated caterpillar fungus catches on in Asia, as it has in the U.S., where much of the supply is cultivated. Many people believe that the prices for caterpillar fungus are ridiculously high and that the bubble will burst soon.

"It is expensive because it is rare and it is rare because it is over-exploited," says Lin Zhibin, a pharmacology expert at Peking University Health Science Center.

Another concern is that the relentless digging on the mountains is contributing to soil erosion and desertification that keeps a perpetual cloud of dust swirling around Golog.

Although the caterpillar fungus has given the nomads a financial boost, Tibetan intellectuals remain ambivalent about its benefits to society as a whole.

"It is not good for the environment or for building harmonious society," says Tseten Dargye, a Tibetan educator and a physician in Dawu, one of Golog's main towns. "People have become territorial. There are a lot of fights between family and friends and the possibility of corruption."

The real problem is that Tibetans themselves have become used to the easy money and the creature comforts it buys -- the motorized transit, the houses, the televisions.

"People can't go backwards. For years, it's been like digging up gold, but more valuable," says Daodu, 31, a teacher. "People today can't survive without it."

barbara.demick@latimes.com