Western Monarchs Are in Trouble: This Is How You Can Help

Imagine that the city of Los Angeles had shrunk to the size of the town of Monterey. You’d be shocked. Basically, that is what has happened to the monarch butterflies that overwinter in California. At Thanksgiving 2018, the population of western monarchs hit a record low of less than 29,000 butterflies, a decline of 99.4% since the 1980s, when the number of monarchs flying to California for the winter is estimated to have been 4.5 million. For every 160 monarchs there were 30 years ago, there is only one left flying today.


Western Monarch Declines - Los Angeles to Monterey
Click on image to enlarge.

The significant problems afflicting western monarchs are habitat loss (overwintering and breeding areas), pesticide use (herbicides and insecticides), and climate change (including increased drought severity and frequency). Research into monarch losses is active and ongoing, but the depth and abruptness of the recent declines means that we need to act now based on the available evidence. The western monarch population may collapse completely if we wait until all of the answers are fully in focus.

Western monarchs are in trouble, but there are concrete actions that we can all take to help them recover. The Xerces Society is taking action for monarchs in California. Working with farmers, natural area managers, California cities, and others we are planting and restoring habitat across the Central Valley—a key breeding and migration area for monarchs. In the last 18 months, we have restored 20 miles of hedgerows on farms, and in the coming year, we will be adding another 10 miles to further re-connect habitats. These hedgerows provide essential nectar sources, milkweed for breeding, and unsprayed refuge. Xerces is also pushing for protection for overwintering sites and working with partners to restore overwintering habitat.

Will you help us in this task?

The actions listed below are based on our current understanding of stressors that impact the monarch specifically, as well as butterflies more generally, and also on the precautionary principle in which we take measures to reduce risks to the monarch population while we are working to better understand these risks.

Download the PDF version of these steps to save western monarchs.

View our more comprehensive western monarch action plan page.

What You Can Do To Help Save Western Monarchs

Restore and Protect Habitat

Plant native milkweed and nectar plants

Heartleaf milkweed
Heartleaf milkweed (Asclepias cordifolia). (Photo: Xerces Society / Stephanie McKnight)

Plant native milkweed species in regions where they naturally occur.

  • • Consult this interactive map to determine if you live in a no-milkweed zone. (In California, milkweeds typically did not grow within 5 miles of the coast.)

If you live in California, plant early emerging species such as heartleaf milkweed (Asclepias cordifolia), California milkweed (A. californica), and woollypod (A. eriocarpa) milkweeds.

Plant flowers to provide nectar for adult monarchs and other butterflies. Ideally, these would be native species which benefit other insects as well, but monarchs can use a wide range of flowering plants. Particular emphasis should be placed on planting species which bloom in the later winter or early spring (blooming February–April) to support monarchs leaving overwintering sites.

  • • Check out Xerces’ monarch native nectar plant guides for regional plant guidance that include bloom time, flower color, and water requirements. In addition to the monarch nectar guides, the table below includes a more general list of native plant genera that monarchs use.
Monarch nectaring on rabbitbrush
Monarch nectaring on rabbitbrush (Ericameria sp.).
(Photo: Xerces Society / Stephanie McKnight)

Climate change is altering when plants bloom and where they can be planted: Choose nectar plants and design planting projects that will be resilient to climate change, such as those with low water requirements, e.g., goldenrod (Solidago sp.), milkweed (Asclepias sp.), coyote brush or mule fat (Baccharis sp.), and rabbitbrush (Ericameria sp. and Chrysothamnus sp.).

Are you a farmer? Check out our publication, A Quick Guide to Monarch Habitat on Farms in California’s Central Valley to learn more about supporting the western monarch population on your land.

Protect existing habitat

Identify existing monarch habitat—which may include milkweed, nectar plants, water sources, or roosting trees—and protect it!

Protect existing milkweed plants from mowing, burning, grazing, pesticides, and other actions that could be harmful to monarchs during the breeding season. Check out Xerces’ Timing Management in Monarch Breeding Habitat Fact Sheet to learn when it is safe to manage milkweed habitat in your area.

Become an advocate for your local overwintering site(s)

If you live on the California coast near an overwintering site, become a steward of one or more sites.

Each year, overwintering sites are destroyed or damaged by human actions such as development or inappropriate tree trimming, sometimes leading to total abandonment of the site by the butterflies.

  • • Participate in community science projects such as the Western Monarch Thanksgiving Count and track whether sites become slated for development or face other pressures.
  • • Contact your local elected officials and encourage them to protect these sites.
  • • Work with local landowners to protect overwintering habitat.
  • • Organize your neighbors to plant native fall-, winter-, and spring-blooming wildflowers and shrubs that provide nectar to monarchs. (See below for information on pesticides and tropical milkweed.)

Reduce or Eliminate Pesticide Use, Particularly Insecticide Use

Green lacewing
Green lacewings are natural predators of aphids and other crop pests. Conservation biocontrol is an environmentally sound alternative to pesticides. (Photo: Judy Gallagher / Creative Commons 2.0 License)

Don’t use pesticides on your lawn, garden, or farm. Protect existing monarch habitat (milkweed and nectar plants) from pesticides.

Avoid purchasing plants that have been treated with systemic insecticides

Check out the pesticide resources on our website to learn more.

If you are able, support farmers who minimize pesticide use and provide wildlife habitat. Many insecticides and herbicides can be harmful to monarchs and their habitat

Contribute to Science and Research

Submitting sightings of monarchs and milkweed is easy and helps to expand the scientific community’s understanding of western monarchs’ life cycles. (Photo: Xerces Society / Stephanie McKnight)

Western Monarch Milkweed Mapper (WMMM): Look for and take photos of milkweeds and monarchs, and report them on the WMMM. Sightings in California during the period monarchs leave the overwintering sites (February–April) are particularly important, as this is a stage of the migratory cycle we know the least about. Other high priority areas where data is needed include New Mexico, Colorado, Utah, Wyoming, and Montana. Report all monarch adult, caterpillar, egg, nectaring, and milkweed sightings to the Western Monarch Milkweed Mapper. Adult nectaring observations are especially needed during the spring and fall migrations.

The Xerces Society’s Western Monarch Thanksgiving Count: If you live near an overwintering site and can make at least a 2-year commitment, consider joining the dedicated group of volunteers that monitor these groves each year, gathering information on habitat conditions and estimating population numbers.

Additional recommended citizen science opportunities include:

Things to Avoid

Tropical milkweed

  • Don’t plant nonnative tropical milkweed and do properly manage tropical milkweed that is already planted!  This includes tropical milkweed (Asclepias curassavica) and balloon plant (Gomphocarpus spp.).
  • • Tropical milkweed interferes with monarch migration, natural behavior during the winter, and can lead to a build-up of disease, especially near the coast in California. Ideally, replace tropical milkweed with native species. If not, cut it to the ground in the fall (Oct/Nov) and repeatedly through the winter, if it re-sprouts. It is important to break the all-year growing cycle.
  • • To find out more, read Tropical Milkweed – a No Grow? on our blog.

Pesticides, especially neonicotinoids

  • Don’t use pesticides and don’t buy plants treated with neonicotinoids. Neonicotinoid treated plants can kill or harm monarchs. Ask your local nursery if they use these chemicals on their plants.
  • • Check out pesticide resources on our website to learn more.

Rearing of monarchs.

  • Don’t rear monarchs as a conservation strategy. Rearing monarchs does not address core issues of the butterfly’s declines and comes with risks such as introducing disease into the wild population. Limit rearing to small numbers (ca. 10 per year) for personal education or enjoyment. Never buy, ship, or move monarchs over long distances.
  • • Read Keep Monarchs Wild! Why captive rearing isn’t the way to help monarchs on the Xerces blog to find out why.

Other Ways to Help

The effectiveness of western monarch conservation efforts depends upon how many people get involved, and how rapidly they mobilize. Spread the word, including on social media. Use the hashtag #SaveWesternMonarchs on Facebook, Twitter, and Instagram to raise awareness, and add a Save Western Monarchs frame to your Facebook profile picture!

Similarly, share your story! Tell us about your work to save western monarchs and you just might get featured on our blog, which will help to inform and inspire others! Email your work to [email protected] and [email protected].

The Xerces Society’s work is only possible with the support of donors like you. Consider making a tax-deductible donation today.

Table 1. Top 15 Native Plant Genera to Provide Nectar to Monarch Butterflies in the Western US. This list is based on actual observations of monarchs nectaring on native plants.

Great northern aster (Canadanathus modestus). (Photo: Xerces Society / Matthew Shepherd)
Genus   Common Name
Abronia   Sand verbena
Agastache   Giant hyssop
Asclepias   milkweed
Baccharis   coyote brush; mule fat
Bidens   beggarticks
Cephalanthus   buttonbush
Cirsium   thistle
Cleome   Bee plant
Ericameria   rabbitbrush
Erigeron   fleabane
Euthamia   goldentop
Helianthus   sunflower
Rosa   rose
Solidago   goldenrod
Symphyotrichum   aster