More Milkweed for the Monarchs

Alliance staff member Tyler Walston inspects a monarch passing through his pollinator garden during the fall migration.

I remember how excited I would get as a child before entering the local butterfly enclosure. My friends, family, and others there were always on the lookout for one of the most iconic pollinators in the Americas – the monarch butterfly. Decades later, while partnering with a monarch conservation group, I was thrilled to see the awe remain in the eyes of today’s children during their yearly monarch release. Crossing borders and biomes, monarch butterflies are still a source of wonder and an inspiring symbol of summer in the Chesapeake Bay.

There are two populations of monarchs in the United States during the summer months – western monarchs and eastern monarchs. Western monarchs have fewer within their ranks and migrate smaller distances, but fly faster. I like to think of them as the sprinters of the two populations, while the eastern insects are more of the marathoners. Eastern monarchs, inhabiting the country from the east of the Rocky Mountains all the way to the Chesapeake, account for approximately 99% of all North American monarchs. Each year, millions of eastern monarchs migrate from their summer homes (some from as far north as southern Canada) to the picturesque oyamel fir forests in the mountaintops of central Mexico.

There, tens to hundreds of millions of monarchs engulf the firs, creating cones of orange and black on the trees’ crests, contrasting with the blue, summer skies above, and displaying fluttering columns draping from the branches below. Their journey to this incredible performance, during which they usually only stop at night or during inclement weather, can cover over 3,000 miles and cross two national borders. Their presence in Mexico has profound cultural meaning as well. Millions participate in el Día de los Muertos (the Day of the Dead) on November 1 and 2, to observe the monarchs as spirits of loved ones returning.

The entire migration process involves four to five subsequent generations of monarchs. The “old guard” monarchs depart from their overwintering sites in the mountains of Mexico in February or March after breeding. They will then lay eggs in northern Mexico or the southern United States, thus beginning the second generation to contribute to the trip back north. The second generation continues, arriving at their summer homes in May. Alas, spring and summer Monarchs can sometimes only have an adult life span of two to five weeks, while the overwintering marathon flyers can live from six to nine months. This short-lived generation wastes no time though, going through their five larvae stages (instars) quickly and breaking out of their chrysalises (cocoons for butterflies) within eight to fifteen days. The last generation of the year, which is usually the third or fourth, are the ones destined to brave the trip back to Mexico the following fall.

Although these western and eastern populations of beautiful creatures generally do not share geography, they do have some profound commonalities. They are symbols of summer and growth, are exemplary of species’ unique, innate behaviors, and most importantly, they are pollinators! Steward’s Corner readers likely already know the importance of pollinators for human health and ecosystem health around the globe. Unfortunately, however, monarch populations have been steeply declining in recent decades due to habitat loss and climate change. Although there have been some sporadic years of increased numbers, the downward trend remains. There is hope yet though, and we as individuals can help. We can plant more.

Monarchs need a variety of native, flowering plants during all stages of their life cycle, the most important of which are species of milkweed, the exclusive host plant of the butterflies. Adult butterflies lay their eggs on milkweeds, and monarch caterpillars (larvae) feed exclusively on the plant. Milkweed plants possess chemical defense compounds consumed and accumulated by monarch caterpillars and pupae for adults to utilize as a defense mechanism against predators. Simply put, no milkweed means no monarchs. Once caterpillars emerge as the butterflies we love, they feed on nectar from other flowering plants. This floral nectar of up to 33 different species of flowers allows them to store fat and sugar, giving them the energy to make their journeys across the continent.

A monarch butterfly caterpillar feeds on common milkweed on Poplar Island in Talbot County, on Maryland’s Eastern Shore on Aug. 18, 2016. (Photo by Will Parson/Chesapeake Bay Program)

If you enjoy a yard, garden, or community space where you can plant freely, consider converting some of it (or all of it for that matter) into a native meadow or pollinator garden. In fact, Alliance staff member, Tyler Walston can give you tips on how to lovingly kill your lawn here. One important factor to consider, however, is when each species you grow tends to bloom. Planting flowers, shrubs, and trees with staggered bloom times can help the early arrivals in the Chesapeake, the larger summer crowd, and those monarchs who may have missed the mass exodus memo. Another aspect to consider is that adult monarchs have been shown to be attracted to yellow, pink, orange, and purple flowers.

The aptly named butterfly weed (Asclepias tuberosa), boasts early orange flowers, from June to August, and the leaves can be a food source during the egg and larvae stages. Some other beneficial native, flowering plants are the sunflower family (Asteraceae), a favorite of the adult monarch, especially goldenrods, which can be easily maintained. Some other good summer-to-fall options in the sunflower family include New York aster (Aster novi-belgii), and New England aster (Aster novae-angliae) which provide nectar from their purple flowers from August to October. These species are also drought and deer resistant, which is helpful in dryer climates or those with pesky grazers. Regardless of the native plants you choose, species diversity with varying bloom times is vital to providing monarchs with the nectar they need to thrive, especially during their arduous fall migration. Some great places to find information on plants that provide nectar for monarchs throughout the season include Xerces Society’s Monarch Nectar Plants of the Mid-Atlantic.

It’s relatively easy to find native plant nurseries nowadays, with the benefits of native flowers, shrubs, and trees gaining more awareness. Please don’t hesitate to visit your local native plant vendor and ask them about converting some of your space into a meadow, or flowering plants with overlapping bloom times. After all, right about now, eastern monarchs are just beginning their journeys back to the Chesapeake from Mexico, so anything we can do to ensure the prosperity of one of our most inspiring and beloved pollinators, we should pursue! Whatever you do, don’t forget the milkweed.