MEXICO CITY – Mexican environmental inspectors say they've found 7.4 acres (3 hectares) of illegal avocado plantations in the Monarch butterfly wintering grounds west of Mexico City.
It's apparently the first time that a wave of avocado planting has directly affected the heart of the Monarch area, a protected nature reserve.
Monarch butterflies migrate from the U.S. and Canada to pine and fir forests that thrive at about the same altitude as prime avocado-growing land.
Previously deforestation linked to lucrative avocado planting had been seen in areas to the west and south of the reserve.
But on Wednesday, the environmental protection office said one man had been arrested for weapons possession at the site.
Without pine trees to provide thermal cover and roosting sites, the butterflies can freeze to death.