Twenty-five years ago, I was visiting Cape Cod during the fall monarch butterfly migration. There were so many monarchs fluttering around that standing still would guarantee some of them alighting on you. It was truly a magical experience that I’ve never forgotten! How sad that the National Wildlife Federation reported in 2018 that monarch populations have plummeted 90% in the last two decades. I hate to think that young people will never get to experience this spectacle of nature. I prefer to be an optimist, so let’s consider some ways that we can help this most beloved of “flutter bys”.
One of the main reasons for population decline is loss of habitat, especially the milkweed plant (Asclepias species). The adult butterfly must have milkweeds to lay their eggs on, as the caterpillar eats only milkweed. This provides both the caterpillar and adult protection from predators because of ingesting the plant’s toxic steroids. Birds have learned to associate the black and orange color with a yucky taste, so other butterflies mimic that coloration for safety. Sneaky butterflies! It is understandable why ranchers would attempt to eradicate milkweed from areas where their livestock graze, but unless you regularly browse in your yard, there is no need to use an herbicide on this important plant. The milkweed flower is also a great source of nectar for many species of butterflies and other pollinators.
Another reason for the rapid decline is the increased use of insecticides without the understanding that not all “bugs” are harmful. Don’t get me wrong, as I will reach for a least toxic product when those nasty green cabbage loopers start to decimate my broccoli. If you’re killing a caterpillar, you’re killing a butterfly or moth. Learn the distinctive stripes and double set of antennae on the larva and you won’t have to worry about destroying a hungry invader ready to decimate your tomatoes (you’re thinking of tomato hornworm).
Adult monarchs feed on the nectar of other flowers as well. Including a wide variety of native flowering species with different bloom times will provide a food source for the monarchs to reproduce in the spring and summer, while providing energy for their fall migration back to Mexico or southern California. Salvia, Indian blanket (Gaillardia), black-eyed Susan (Rudbeckia) and coneflowers (Echinacea) provide food in the spring and summer. During the fall, our ubiquitous rabbit brush is a magnet for many species of butterflies. Other fall blooming plants that are great sources of fuel for migrating butterflies are blazing star (Liatris), goldenrod, aster, hummingbird mint (Agastache), and sunflowers.
Speaking of mistaken identity, some of you may have been surprised to see goldenrod on the list of desirable plants. Why add something that would flare up allergies? Poor goldenrod has gotten a bad rap because it blooms the same time as ragweed, the real culprit. They even grow together in the wild, but ragweed is rather nondescript with inconspicuous blooms. Sneaky ragweed! Goldenrod’s pollen is large, meaning it is designed to be carried by pollinators. Ragweed’s pollen is quite small, indicating it is windborne, just like our cedar pollen in early spring.
Further information can be found at Monarch Joint Venture, Xerces Society for Invertebrate Conservation, and the National Wildlife Federation. You can even have your garden certified as a wildlife habitat through the National Wildlife Federation. One of my former clients in Austin went through the process and now proudly displays the sign as a justification for his leisurely gardening techniques. Sneaky gardener!