With their bright orange and black wings, monarchs are one of the most easily recognizable butterflies. They’re found coast to coast in the United States, and they’re one of the species most likely to show up in a butterfly garden. But there’s more to the story. The monarch in your garden is like a long-haul trucker stopping for a meal—this little creature travels hundreds or thousands of miles in its lifetime. And you can be part of this butterfly’s incredible journey by planting milkweed, the one plant absolutely essential to the monarch’s life cycle.
Be part of a massive migration. Monarchs are well known for their long-distance, multigenerational seasonal migration. Each fall, monarchs fly thousands of miles on their delicate wings to ancestral roosting sites, where they spend the winter months semi-dormant in large colonies. Western monarchs migrate to dozens of locations along the California coast, where they cluster in native trees and the ubiquitous and exotic eucalyptus.
East of the Rockies, monarchs make a more dramatic migration. They fly from southern Canada and the northern United States all the way down to a handful of high-elevation sites in the mountains of Mexico, where they roost in the millions. It’s breathtaking to see so many monarchs hanging in the trees that their collective weight sometimes breaks branches, and to hear the sound of millions of butterfly wings flapping on warm days when the monarchs take flight to sip water from puddles.
One of the most fascinating aspects of this migration is that it takes place over several generations. The last generation of the summer hatches at the northern limit of monarch range. That generation delays sexual maturity and, triggered by the changing season, begins the 3,000-mile journey to Mexico, where they spend the winter. In early March they reach sexual maturity and head north, mating as they go. Some get as far as southern Texas, where the females lay eggs and die. The next generation hatches and, after completing metamorphosis, heads north and east and repeats the process.
Over three or four more generations, they repopulate the rest of the continent east of Rockies, until the last generation of the season begins the southern migration again. A similar, though shorter, migration happens west of the Rockies as monarchs overwintering in California head north.
Understand the milkweed connection. Butterfly gardens must provide food for both adults and caterpillars. Monarch caterpillars feed exclusively on milkweed, a double-duty plant that also serves as a nectar source for adult butterflies. Milkweed also has a sap that contains alkaloids, which make the insects taste bad to birds and other predators. The striking coloration of the monarch evolved as a warning that tells predators, “Don’t eat me; I taste bad.”
Make a monarch garden. Start your monarch garden by planting milkweed species such as swamp milkweed (Asclepias incarnata), butterfly weed (A. tuberosa), antelope horns (A. asperula), and common milkweed (A. syriaca). If possible, choose a species that’s native to your region.
Plant native perennials to provide nectar from spring through fall. Because monarchs migrate, late-season nectar is particularly important. Some good choices include coneflowers (Echinacea spp.), ironweed (Vernonia spp.), Joe-pye weed (Eupatorium spp.), sedum (Sedum spp.), verbena (Verbena spp.), asters (Aster spp .), and goldenrod (Solidago spp.).
Add some dense shrubs where the butterflies can hide from hard rains and strong winds. Don’t use insecticides, which can kill butterflies. Then sit back and wait for these orange and black beauties to arrive.
Avoid Butterfly Bush
Butterfly bush (Buddleia spp.) has long been a staple for gardeners trying to attract butterflies, and there’s no doubt that butterflies find the shrub irresistible. An import from Asia, butterfly bush comes in many colors and grows in a variety of conditions. However, butterfly bush has become invasive in some parts of the country, notably the Pacific Northwest and the Mid-Atlantic region. Choose native perennials and flowering shrubs instead.