Monarch butterflies arrive in Mexico for annual migration

Monarch butterflies have begun their annual migration to Mexico, arriving in time for the Day of the Dead celebrations in Michoacán and the State of Mexico. The migration, which covers over 4,000 kilometers from Canada and the United States, was aided by a cold front that brought the first specimens across the border in early October.

Researchers are utilizing advanced tracking technology to monitor the journey. Using ultra-lightweight solar transmitters known as BlūMorpho, which weigh only 60 milligrams, scientists have increased the number of tracked butterflies from 400 to 1,337. These devices allow for precise data collection on migration routes and resting sites.

For visitors to the Monarch Butterfly Biosphere Reserve, the official 2025–2026 season is scheduled from November 22, 2025, to March 31, 2026. Key sanctuaries include Sierra Chincua, Senguio, and El Rosario in Michoacán, as well as Piedra Herrada in the State of Mexico. Visitors are advised to follow local regulations, which include mandatory guided tours and specific visiting hours from 09:00 to 17:00.