Sometimes you need some good news and motivation, and we have some for you today–the western monarch butterfly population has increased! Biologists and volunteers count overwintering monarchs in coastal California each year. During the fall of 2021, the Xerces Society counted nearly 250,000 butterflies compared to less than 2,000 butterflies counted during fall 2020. Although that is merely a sliver of the millions of monarch butterflies that migrated in the 1980s and ‘90s, the increased count this year is encouraging. 

Did you know that there are two populations of monarch butterflies in North America? The eastern group breeds east of the Rocky Mountains and overwinters in Central Mexico. The western population breeds west of the Rockies (including in the Eastern Sierra) and overwinters in coastal California to escape the cold weather. Monarchs are unique–not many insects migrate!

Map of monarch butterfly migration

USDA Forest Service

Habitat loss and fragmentation, pesticides, and climate change have all unfortunately contributed to the decline in monarch butterflies in North America. The removal of milkweed and nectar-providing plants from agricultural fields and roadsides has also impacted them. Monarchs need milkweed—it is the only food that the caterpillars will eat and the only plant that monarchs will lay their eggs on. As caterpillars eat toxic milkweed leaves, they store the toxins in their bodies. This makes them taste bad to predators, even as adults!

Caterpillar on leaf

Conrad Barrington/

Do you want to help motivate monarch butterflies to continue to make a comeback? Learn about ESLT’s Eastside Pollinator Garden Project here to get started on your monarch-friendly garden. ESLT will provide help planning your garden, and you may be eligible for a voucher for milkweed and other native plants. 

And join us for ESLT’s free Pollinator Garden Workshop from 10am-12:30pm on April 9th! Local gardeners will present on topics to help you design a beautiful garden that will provide food and habitat for monarchs, birds, bees and butterflies. You can learn more about this event here and RSVP to Claire at .


Western monarch populations grew over 100-fold in 2021. Why?” by Alissa Greenberg

The butterflies are back! Annual migration of monarchs shows highest numbers in years” by Michael Levitt and Christopher Intagliata

National Geographic


National Wildlife Federation