The western monarch butterfly (Danas plexippus) is in peril and not just dire but enough to be of such concern that in 2014 a petition was submitted to the United States Fish and Wildlife for consideration as an endangered species. On December 15th, 2020 we finally got that decision, United States Fish and Wildlife Service (USFWS) deemed the western monarch butterfly was “warranted but precluded” to be put on the Endangered Species Act.  Western monarch butterflies are in what is called an extinction vortex. Western monarchs have declined from millions in the ’80s to less than 2,000 from the current western monarch Thanksgiving count done by the Xerces Society every year. What is of more concern is another count is done at New Years and typically there is about a 40% reduction in butterflies from the Thanksgiving count to the New Year’s count.

Much is needed to save this iconic butterfly but the actions needed to take a concerned collective effort from cities, large landowners, many private landowners, and citizen scientists. The thing that we can do on the central coast is plant habitat, lots of nectar plants for the monarch butterflies. Planting nectar plants give them much needed fuel for their migration and breeding cycle.

I am a Monterey Peninsula native. I was born in Carmel and grew up on the Monterey Peninsula and remember looking up from the playground in the fall and seeing thousands of monarch butterflies flying overhead returning to the overwintering sites along the central coast. Also, our local school district from kindergarten on always had the monarch butterfly in our curriculum. This butterfly has often stirred immense desire to work diligently to save it and yet we are now facing a most dire situation. What can be done, I’m often asked.  Many try to plant more milkweed but milkweed alone will not save monarchs. There is no one reason but many reasons why the numbers keep falling of this iconic butterfly. It is degradation of over-wintering sites, loss of habitat, climate change, our summers are getting hotter and the wildfires have contributed to a loss of habitat, loss of native plants and chemical use regarding insecticides and herbicides. There was a current study that sampled milkweed and found pesticide contamination in all samples. Their findings found 25 different insecticides 27 fungicides, 11 herbicides and 1 adjuvant. 

It is important to note that Tropical milkweed (Asclepias curassavica) commonly sold in box stores and a colorful milkweed but should be avoided in planting as it has been problematic regarding OE (Ophryocysis elektroscirrha) a debilitating protozoan parasite that infects monarchs and can possibly be contributing to the decline as well. One of the other factors of tropical milkweed which is not a native milkweed and such does not die back in the winter as native milkweeds do is continue to grow year-round on the central coast. The OE spores continue to collect on the plant and since the plant does not get cut back or die the monarchs stay to feed and lay eggs and not go into diapause (a form of rest, of suspended development during the winter) and then when conditions are favorable such as temperature and season change the monarch begins their migration and leave over-wintering sites breeding, looking for milkweed and nectar for their migration journey. Milkweeds should not be planted in areas that are within five miles of the coast as they were not historically growing there and as to not disrupt the reproductive cycle of the monarch butterflies. Also, there is a concern from the latest studies that hand-raising monarch butterflies can contribute to weakening their migratory instincts and also alter their DNA. Then quite possibly as they mate with wild monarchs weaken and alter the gene pool. 

The decline of the monarch butterfly began in the 1980s and continues today but there is hope. Many species have been brought back. There is hard work ahead of us for it will take a collective effort to bring up the numbers. Please contact the Xerces Society xerces.org for more information.