Planting your garden for people and butterflies
By Rachel Mackow
The summer sun brings on ever more flowers in the garden, and, mysteriously, butterflies appear. This pollinator’s life is touched by a bit of magic. An adult butterfly lays a pinhead- sized egg from which a tiny caterpillar hatches. That caterpillar dines on its host plant until it is big enough to build a cocoon around itself. Then the caterpillar metamorphoses from a many-legged crawling creature to a winged one that emerges and flies away, perhaps to your garden. Once there, that butterfly helps to pollinate your plants.
Butterfly life histories are as diverse as they are. Some butterflies survive the winter as eggs (for example, the banded hairstreak), others in cocoons (the black swallowtail) and still others as adults (the mourning cloak). From spring to fall, caterpillars and butterflies are present in my garden. While the butterflies provide beauty and pollination services, their caterpillars also provide food for my other favorite garden visitors—songbirds.
For most butterflies, native plants are key. Mature butterflies that feed on nectar are somewhat flexible. They can utilize many different flower species, so providing a full season of blooming flowers will cover many adult butterflies’ needs. Their caterpillars, however, usually require a specific host plant—these being native plants with which they have co-evolved. So while many nectar plants invite butterflies over for a snack, certain native plants invite them to stay and start a family. By my count, there are at least 15 delicious edible plants—good eating for humans—that also serve as host plants for butterflies. This summer, if you want to be surrounded by nutritious home-grown food and beautiful insects, consider adding a few of these host plants to your garden.
Some gardeners, especially those who grow plants in the mustard family—cabbage, broccoli, cauliflower and kale— might bristle at sharing their crops with a caterpillar. The caterpillars of the cabbage white butterfly (Pieris rapae), a non-native species, are voracious and prolific, leaving more holes than foliage on their host plants.
But native butterflies don’t typically cause significant damage to host plants. They usually lay eggs singly or in small numbers. Some butterflies do occasionally have spikes in population though. In May 2012, I recall the massive flight of red admiral butterflies passing through Plainsboro. These nettle-eating beauties spike cyclically, about once every ten years. I’d gladly share my nettle patch just to be surrounded by hundreds of butterflies again.
But there are other good reasons to plant your own nettle patch. The stinging nettle is a highly sought-after spring edible, packed with vitamins and minerals. Nettles can be used as a green vegetable, herb or tea. Stinging nettle is also a popular addition to artisan cheeses. Planted at home, it’s a “cut and come again” kind of plant. It surpasses mint in its ability to spread in a garden, but keep in mind that it lives up to its name—it stings.
Red admiral caterpillars also host on wood nettle, a native plant of partly shaded stream sides and river banks that can be used in the same ways as stinging nettle. On one nettle-foraging excursion, I unwittingly brought home an exquisite red admiral chrysalis that appeared as though it was speckled with gold leaf. My family kept the chrysalis in the kitchen until one morning we found a fresh red admiral on the windowsill.
For permaculturists and homeowners looking to create perennial plantings that attract butterflies, native trees with edible fruits and nuts are a good choice because they host an array of these beautiful insects. Hackberry, hickory and black cherry fit the bill. Many shrubs are options, too, with blueberries and native viburnums also serving as butterfly host plants.
Plant a hackberry, and you’re inviting quite a few hungry caterpillars for dinner—American snout, hackberry emperor, mourning cloak, question mark, and tawny emperor caterpillars all like hackberry foliage. Each of these butterfly species lives up to its unusual name. They are spectacular. And for hungry people, hackberry has small, sweet fruits that can be eaten fresh.
Black cherry foliage, considered inedible and even poisonous to people, hosts red-spotted purples and tiger swallowtails. The latter species is large and has bold yellow-and-black stripes. Because tiger swallowtails use a variety of tree species as hosts, they are a familiar sight in New Jersey. While their caterpillars nibble the foliage of black cherry, most human foragers are after the fruit, which can be eaten fresh or cooked into pies, jams and syrups.
Hickories bear edible pecan-like nuts, and host a diminutive silvery- gray butterfly called the banded hairstreak. A row of blueberries or native viburnums such as nannyberry, American cranberry bush or blackhaw might draw small, titanium-white to bluish butterflies— the spring azure—as well as offering edible berries to the gardener.
There’s a big exception to the native plant rule: the black swallowtail caterpillar feeds on the foliage of parsley, dill, fennel and carrots. Its dining preferences have earned it the nickname “parsley worm.” This caterpillar has an interesting defense mechanism: When it’s disturbed, it expands a forked gland on its head that mimics a snake’s tongue. It also emits an unpleasant musky odor. This may fascinate your naturalist pals and kids in the garden.
In our garden, black swallowtail caterpillars seem to prefer succulent dill and fennel foliage to carrots and parsley. We had over a dozen caterpillars on just a few fennel plants this summer. My son, Beren, was alarmed by their presence on his favorite vegetable, so we agreed that the two biggest fennel plants were “his.” Any hungry caterpillars would be moved gently to adjacent fennel plants. It turns out there was plenty for all of us.
THE MIGHTY MONARCH
Of all the butterflies of the Northeast, the monarch butterfly is perhaps the most iconic. Like many birds, this bright-orange-and-black butterfly migrates with the seasons. Once common, the monarch has declined from an estimated 1 billion individuals in the 1990s to about 35 million in the winter of 2013. Large populations are required for the species to survive. Experts are petitioning for this butterfl y to be protected under the Endangered Species Act. Habitat loss and pesticides are implicated in its decline.
Milkweed is the monarch butterfly’s host plant. There are many species of milkweed—common, swamp, purple, orange butterfly milkweed and more. Each contains toxins that the monarch can ingest without harm but that result in the butterfly becoming unpalatable or toxic to predators.
Turns out people can be milkweed specialists, too. Pay attention here—like any specialist, you have to know your stuff. Common milkweed (Asclepias syriaca) is people food when it’s harvested and prepared properly. The young shoots, the young, green flower buds, and the young seedpods can be eaten when cooked. They can also be cooked and pickled. Consult a reputable foraging book for identification and preparation details. The Forager’s Harvest (2006), by Sam Thayer, has extensive information on common milkweed.
Remember, this common “weed” is now a delicacy. You’re breaking bread with the butterflies. Just like at the neighborhood barbecue, you always leave the last serving, even if it’s really good. More guests are arriving. The monarch family is on the way, and they are really, really hungry.
RESOURCES FOR LEARNING MORE:
Xerces Society (xerces.org)
North American Butterfly Association, New Jersey Chapter (naba.org/chapters/nabanj)
Bringing Nature Home by Doug Tallamy, [Timber Press, 2009]