– The green volcanic hills that tower above Apútzio de Juárez have begun to fill with swarms of monarch butterflies, which return each year for the winter stretch of their celebrated — and imperiled — migration.

But downhill from the monarchs’ mountain roost, in the oak and pine forests that border this small farming town, there lurks a new threat to their winter habitat: a lust to grow the lucrative avocados that are being consumed at record rates in the U.S.

Spurred by soaring demand for the creamy fruit, farmers in the western state of Michoacán are clearing land to make room for avocado orchards, cutting oak and pine trees that form a vital buffer around the mountain forests where the monarchs nest.

“It’s scandalous what people are doing now to grow avocado,” said Arturo Espinosa Maceda, who has for years grown avocados, peaches and strelizia flowers at a farm some 12 miles north of Apútzio. “But it’s mega-business.”

Apútzio sits on the western edge of the Monarch Butterfly Biosphere Reserve, a 135,000-acre protected area where the butterflies rest on oyamel, or native fir, trees. The butterflies’ numbers have dwindled sharply in recent years, as milkweed declined in the U.S. and deforestation affected their Mexican habitat. Each year environmentalists hold their breath to see how many butterflies will arrive in Mexico.

Omar Vidal, director general of the World Wildlife Fund in Mexico, said that conserving the winter sanctuary was “fundamental to the survival of the migration.”

Deforestation “has to be reduced to zero,” he said.

But the avocado boom could complicate that goal.

Americans ate a record 7 pounds of avocado per capita in 2015, twice as much as in 2008, according to the Department of Agriculture. Nearly 80 percent of those avocados came from Michoacán, the only Mexican state authorized to export the fruit to the U.S. by the department, which bans avocados from other Mexican regions over fear of pests. Michoacán doubled its avocado exports over the past seven years to 770,000 tons — worth roughly $1.5 billion.

The bonanza has been brutal for Michoacán’s oak and pine forests, which grow at 5,000 to 7,000 feet — the same altitude as avocados. Between 1974 and 2011, about 110,000 acres of forest across Michoacán’s central highlands were turned into avocado orchards, according to a study by the National Autonomous University of Mexico.

And deforestation is accelerating, experts said. Jaime Navía, president of GIRA, a nonprofit organization based in Michoacán that promotes sustainable rural development, estimated that 65,000 acres — most of it forest — had been converted to avocado growing since that study.

“The damage is irreversible,” he said.

Officials have blamed producers looking for a pretext to turn land over to avocado orchards for a spike in the number of forest fires in Michoacán this year. But forestry experts and farmers said that Mexico’s environmental watchdog, the Federal Attorney for Environmental Protection, often turned a blind eye to abuses. Officials are fearful of powerful interests, they said, especially given that organized crime has links to the industry, or bribes make the officials pliant.

“The authorities need to control this,” said Armando López Orduña, general director of the Mexican Avocado Producers and Packer-Exporters Association.

To offset deforestation, the association has planted half a million trees since 2009 and hopes to plant another half-million by 2018, he said.

Around Apútzio de Juarez, a town of 1,100 people surrounded by fields of guava and corn, scars on the hillsides and patches of young avocado trees signal the crop’s advance. Some have farmed avocado for decades. But now, growers from other areas are buying land.

Davíd Romero Hernández, a stocky farmer who was trimming grass in his new avocado orchard on the edge of Apútzio one morning in October, said that the land had been covered with oak and pine. But the owner felled the trees a year ago and sold it to him.

Romero, 51, pointed to a shorn hill above his plot. That, too, was also covered in forest until a few months ago, he said. Then a farmer from another village bought it.

“It’s the ambition of avocado,” he said.

That ambition could soon increase. Zitácuaro, the municipality surrounding Apútzio, is seeking certification to export avocados to the U.S. — a fact that is on the lips of every farmer.

Certification is awarded municipality by municipality, and not all of Michoacán can export avocados. As it stands, some of Apútzio’s avocados are sold to buyers from Uruapan — a town 100 miles west that is the heart of the industry — who pass them off as having been grown there.

Deforestation in Apútzio is a recent problem and far less extensive than in other areas of Michoacán, experts said. But “it is becoming a significant problem,” given the area’s proximity to the monarchs’ habitat, said Edgar González Godoy, director in Mexico of the New York-based Rainforest Alliance.

Efforts to fight deforestation in the reserve focus on about 34,000 acres around where the butterflies roost. Programs run by the World Wildlife Fund and other organizations have helped cut logging from hundreds of acres each year to just 28 so far this year, said the fund’s Vidal.

But the trees in the reserve’s outer ring play an important role, said Manuel Sarmiento, a biologist and member of the Alliance for the Conservation of Forests, Land and Water, a group of local farmers, environmental activists and residents.

For example, the trees cool the air from Michoacán’s warm western plains as it rises toward the oyamel forests in the center. If the temperature at the heart of the reserve, about 7 miles from Apútzio, were to rise, the oyamel could suffer, and thus the butterflies would suffer, too, he said.

González worries that the lure of avocado will only grow if Mexico succeeds in opening new markets. He noted that deforestation is increasing in Jalisco state, another area that hopes it will soon be able to export its crop to the U.S.

“Just imagine what would happen if the Chinese started eating avocado,” he said.

In town, residents said avocado had put money into empty pockets. Workers make about $7.50 per day to tend the orchards, and twice that during harvests. A resident can sell 1 acre to an avocado farmer for about $4,300 — more than that seller would typically make in a year.

“People have more to spend and that lifts us all,” said Fernando Bernal, a butcher, as he hacked slabs of pork from a loin.

But like others in Apútzio, Bernal worries about water. Apútzio’s supply comes from springs fed by the hills east of town. Pine and oak help water filter through the earth and into the spring; avocado, on the other hand, has shallow roots and consumes a lot of that water. If people keep cutting down the forest, “we’ll run out,” Bernal said.

And Apútzio isn’t the only community with much at stake. The hills that stretch northeast collect water for the massive Cutzamala water system that supplies the thirsty Mexican capital, Mexico City, 100 miles away.

Even Romero, happily tending his avocado bushes on land once filled with mighty trees, is saddened by the loss of forest. He said that his village, Zicata de Morelos, depends on water that comes from the hills near Apútzio.

“So we’re all affected,” Romero said. “But people don’t think about the future.”