Simple Support for Western Monarchs

Every winter, volunteers travel to western monarch overwintering sites to count butterflies roosting in trees near the coast. Last winter, fewer than 2,000 monarch butterflies were found overwintering along the California coast.

Overwintering monarchs November 2015. (Kathy Keatley Garvey)

Compared to 1997, when it was estimated that more than 1 million monarch butterflies overwintered, the numbers from the 2021 count were historically low.

Emma Pelton and Stephanie McKnight of the Xerces Society write, “Iconic and beloved monarch overwintering sites like Pismo Beach and Natural Bridges reported only a few hundred monarchs during the count. More startling, Pacific Grove, which goes by the name “Butterfly Town, USA” because of its overwintering sites, had no monarchs at all. Each of these sites normally host thousands—in some years, tens of thousands—of butterflies during the winter months, and are locations where visitors travel to experience the marvel of glittery orange monarch clusters.”

Scientists are not sure exactly why the overwintering monarch butterfly numbers were so low last winter, but they know that wildfires, increasing use of pesticides and herbicides, climate change, and habitat loss are some of the culprits. 

Western monarch butterfly. (E. Wallace)

What can we do to help western monarch populations recover? 

Plant native: Plant milkweed that is native to the area where you live. For Southern Californians, you can find native milkweed at Roger’s Gardens in Corona del Mar and Tree of Life Nursery in San Juan Capistrano.

Plant pesticide free: There is a dizzying array of chemicals available to kill insects in your home and garden. But many of these pesticides kill beneficial insects like monarch butterflies as well. The Xerces Society writes:

“‘Pesticide” is an umbrella term that includes—but is not limited to—insecticides, herbicides, fungicides, and rodenticides. Each year in the United States, more than a billion pounds of pesticides are applied across home gardens, parks, and farms to manage unwanted weeds, insects, diseases and other ‘pests.’ The majority of pesticides used are ‘broad-spectrum’ meaning they kill broadly. Contamination resulting from the extensive use of pesticides has been tied to the decline of species important to ecosystems, including pollinators.”

A beneficial insect, the praying mantis, hanging out on a pesticide-free narrow-leaf milkweed. (E. Wallace)

Xerces also writes about the dangers of using herbicides: “Herbicides may kill plants or, in the case of pre-emergent herbicides, prevent plant germination. Herbicides can indirectly impact pollinators and other invertebrates by eliminating habitat. For example, declining populations of the monarch butterfly have been linked to increasing herbicide use—because that, in turn, leads to the loss of milkweed and nectar plants that monarchs rely on.”

Instead of reaching for a pesticide, consider planting a more diverse plant palette in your home landscape to attract beneficial insects and provide support for birds and other predators to pests. To learn more about pesticides, click here.

This video shows a monarch caterpillar climbing on native milkweed, on its way to finding more milkweed leaves. This video is in real time. The caterpillar is speedy! (E. Wallace)

We can all provide a healthy environment for creatures living in our home landscape. A healthy garden will support western monarch butterflies as they seek out nectar this summer. And when a female monarch butterfly finds native milkweed in your yard, she can lay eggs there. Your native milkweed will provide food for caterpillars to munch and grow.

Monarch caterpillars eating woolly-pod milkweed. (E. Wallace)

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