Monarch butterfly numbers plummet in US west coast winter habitats

Just 9,119 were counted in 2024 - down 96% on previous year and second-lowest mark in nearly three decades

The number of monarch butterflies spending the winter in the western United States has dropped to its second-lowest mark in nearly three decades as pesticides, diminishing habitat and the climate crisis take their toll on the beloved pollinator.

The butterflies, known for their distinctive orange-and-black wings, are found across North America. Monarchs in the eastern US spend their winters in Mexico, while monarchs west of the Rocky Mountains typically overwinter along the California coast.