Last week, one of our gardeners witnessed something surprising and important for NYC and for the natural world in general – a monarch caterpillar was perched on one of the plants by the Diller – von Furstenberg Sundeck. The sighting calls for celebration: this once-common insect is currently facing some difficult times. Monarch butterflies – one of the most recognizable butterfly species in North America – are now undergoing a staggering decline in numbers.
According to Sarina Jepsen, director of the endangered species program at The Xerces Society for Invertebrate Conservation, in an article in Wildflower Magazine, "Twenty years ago, North America was home to more than a billion monarchs. Sixty million were estimated in 2012-13. Today's estimate is fewer than 35 million."
(Monarchwatch.org) Fall and spring migration patterns for the monarch butterfly show that our caterpillar made it to the High Line right on schedule.
How could a decline this dramatic have occurred in such a short amount of time? The drop is attributed largely to habitat loss and the destruction of a native plant that is very important to monarchs – milkweed. In a sense, the monarch butterfly and the milkweed plant mature together. Monarchs begin their life cycles as eggs and hatch as larvae that eat their eggshells as well as the leaves of the milkweed plants on which they were born. The insect remains dependent on milkweed throughout its life the plant is the monarch caterpillars' primary source of nourishment, and the only plant on which adult monarchs will lay their eggs.
Until recently, milkweed was abundant in the Midwestern United States, where half of monarchs are believed to begin their migration south in the fall. Now, the Midwest milkweed habitat is "virtually gone" with 120–150 million acres lost. Conservationists attribute the disappearance of the milkweed species to agricultural practices in the Midwest, such as the large-scale use of herbicides, which have effectively killed off the plant.
Located next to the Diller – von Furstenberg Sundeck, the swamp milkweed where our monarch caterpillar was found.
Now more than ever, the decline of milkweed species in agricultural areas in the Midwest make other habitats all the more important. Gardens abundant in milkweed and nectar plants can serve as rest stops for adult monarchs and nurseries for their eggs. With our new tiger-striped friend making the High Line its temporary home, our gardeners were encouraged to see that the park's abundance of milkweed was providing some much-needed habitat. By fostering native varieties of milkweed at your own home, one of these habitats could be your garden as well.
Milkweed can easily be grown from seed in home gardens. Although there are over 100 species of milkweed, the most commonly available and widely adapted include the common milkweed (Asclepias syriaca), swamp milkweed (Asclepias incarnata ssp. pulchra) and butterfly milkweed (Ascelpias tuberosa). On the High Line, swamp milkweed, purple milkweed (Asclepias purpurascens), and butterfly milkweed are currently in bloom this month. Not only are these plants physically beautiful, but they also attract a multitude of beneficial garden insects. Be sure to plant a variety native to your region—in the northeast, these include the common milkweed, swamp milkweed, butterfly weed, whorled milkweed (Asclepias verticillata), and poke milkweed (Asclepias exaltata).
The purple milkweed, found on the High Line between West 15th and West 17th Streets.
Butterfly milkweed, pictured above, is a native of the eastern United States and Canada that's a favorite among monarch butterflies and other pollinators.
Monarchs born in late summer or early fall are born to fly; they know that because of the changing weather they must prepare for their massive winter migration for which they are known for. As July comes to a close and fall peeks just above the horizon, making the High Line and surrounding neighborhood gardens a habitat for monarch butterflies can truly help protect these beautiful insects as they migrate, and perhaps make a small step to help reverse their unfortunate decline.