Monarch 101

The weather is getting warmer, and we are approaching the time when it is safe to start gardening, specifically clearing last year’s brush and planting new flowers for this year. If you need a refresher about what to do when, I have a post from last spring about how you should wait until nighttime temperatures are reliably above 40F before you start clearing debris and stalks from the previous year’s plants.[1]

I’m thrilled to say that I had a wider variety of visitors to my pollinator garden last year (year two) than the year before. Starting on year three now, I want to continue building out the variety of plants to make sure I’m supporting additional at-risk species, not just bees. Last year a beautiful monarch butterfly began frequenting my butterfly bushes, but I felt bad that I didn’t have any milkweed, which is the only plant they can eat. I won’t be making that mistake again.

Dwindling Numbers

Monarch butterflies are native to North America, with populations on the east and west coasts, and most of them migrate to fir forests in central Mexico for winter. Their numbers have been declining for several years: counts in the 1990s showed 1 billion in the east and 1.2 million in the west; 2018 counts showed 225 million in the east and fewer than 30,000 in the west.

Threats to the monarch population are many:

Illegal logging continues in Mexico, drastically reducing the available overwintering space. Sadly, in the course of researching this article, I found not one, but two stories about butterfly activists who were found dead, likely after opposing logging activities in butterfly preserves.[2],[3]
Increased use of herbicides at the industrial scale is killing off massive amounts of milkweed, their only food source. Several monarch advocacy groups and studies point to the use of glyphosate on Roundup-Ready crops such as soy and corn as a major factor – milkweed that often grows on the borders of these fields cannot survive.[4]
Urban growth and industrial development have been destroying native habitats, including 70-plus acres of the National Butterfly Center in Texas, which will be bulldozed for the planned border wall.[5]
Changing weather patterns have resulted in unfavorable conditions during migration and breeding.[6]

I was thrilled to see this monarch and swallowtail checking out my butterfly bushes.
I was then saddened to learn that butterfly bushes are not native, are actually considered invasive in Pennsylvania, and cannot provide food to monarch caterpillars.
If you want to help the monarchs, ditch the butterfly bushes and grow some milkweed.

Thanks to pressure from conservationists, in 2014 the US Fish and Wildlife Service agreed to launch a review to determine if additional protections were warranted under the Endangered Species Act. Unfortunately, the review is still underway, with the decision date extended to December 2020.[7]

What You Can Do

Apart from traveling to Mexico and protesting illegal logging there, I wanted to know what I could do to help support these beautiful and delicate creatures. As it turns out, there are more options than you might think:

Support advocacy organizations such as Save our Monarchs[8] and Monarch Watch.[9]
Avoid purchasing GMO soy and corn, as increased demand for those products increases the use of glyphosate on Roundup-Ready crops.
If you are buying wood for a project, make sure it is certified by the Forest Stewardship Council; FSC-certified wood will not have been sourced illegally from monarch habitats.[10]
Don’t use pesticides or herbicides in your own garden.
And, of course, grow your own milkweed.[11]

It is important before planting anything in your garden that you check to make sure it is native to your area. Non-native species typically have no predators and can easily take over, crowding out plants that feed native insects. Most states (and/or local gardening resources) maintain lists of native species in your area and invasive species that you should avoid.

Make sure you do your research before simply buying plants or seeds you like. Choose native plants whenever possible and avoid invasive species.
These are the three most common types of the 11 milkweed species native to Pennsylvania.

Butterfly bushes were the first thing I planted in my pollinator garden two years ago, and I was shocked to find out afterwards that not only are they non-native, but they are considered an invasive species in Pennsylvania. Although they look pretty and produce nectar that many butterflies enjoy, there are no native caterpillars that can feed on them. Apparently their seeds spread very easily as well, though that has not been my experience because I dead-head them throughout the summer.[12]

There are 140 species of milkweed, 11 of which are native to Pennsylvania. The three most common ones are Common Milkweed (Asclepias syriaca), Butterflyweed (Asclepias tuberosa), and Swamp Milkweed (Asclepias incarnata). Monarchs only lay their eggs on milkweed plants, and monarch caterpillars only eat milkweed. The plant itself is toxic to most birds and mammals, meaning that monarch caterpillars also become toxic to their natural predators.[13]

My aunt and uncle own Pharo Garden Centre in Bethlehem, PA,[14] and I have referenced their extensive organic gardening expertise on my blog before. They grow all three kinds of milkweed mentioned above in their greenhouse and gave me the low-down on each:

Common Milkweed (syriaca) was what their caterpillars vastly preferred, with its broad leaves;
Butterflyweed (tuberosa) is small and must be kept dry in well-drained soil because the stems will rot easily;
Swamp Milkweed (incarnata) was a favorite of their aphids, so if you choose this one be prepared with a good aphid-eater like ladybugs or lacewings.[15]

My aunt frequently sends pictures of baby animals that have taken refuge at her garden center, like this monarch caterpillar.
Photo credit: Victoria Leister

Unfortunately, given current travel restrictions due to COVID-19, I cannot drive out to Bethlehem to load up my car with plants like I do every spring. The alternative is growing my own, so I purchased several seed packets online. The one thing you must remember if you grow your own milkweed from seeds is that you must stratify them before planting – meaning they need to think they have gone through a winter in the ground. The easiest way to do this is put your seed packets in the fridge for a month (instructions on the packaging will tell you to do this for two weeks, but they really need a minimum of four). As usual, I’m a little behind schedule on this, so my seeds are still chilling out and probably won’t make it into the ground until June.

I hope to provide an update in several months with photos of milkweed plants and several stages of monarch life. Do you have milkweed and/or monarch stories from your own garden? I’d love to hear about them below.

Thanks for reading, and happy gardening!

[1] https://radicalmoderate.online/spring-garden-cleanup/

[2] https://nypost.com/2020/01/30/homero-gomez-gonzalez-prominent-butterfly-activist-in-mexico-found-dead-in-a-well/

[3] https://www.bbc.com/news/world-latin-america-51356265

[4] https://onlinelibrary.wiley.com/doi/epdf/10.1111/icad.12198

[5] https://www.ecowatch.com/border-wall-national-butterfly-center-2638893129.html?rebelltitem=1#rebelltitem1

[6] https://www.independent.co.uk/news/science/climate-change-mexico-monarch-butterfly-science-a9273471.html

[7] https://biologicaldiversity.org/w/news/press-releases/eastern-monarch-butterfly-population-plunges-more-half-2020-03-13/

[8] https://www.saveourmonarchs.org/about-us.html

[9] https://monarchwatch.org/

[10] https://us.fsc.org/en-us

[11] https://www.onegreenplanet.org/environment/ways-you-can-help-save-the-monarch-butterfly/