The monarch (Danaus plexippus) is the classic poster child of butterflies, at least in North America. There are plenty of good reasons for this. It’s large and gorgeous. Its annual migratory pattern is a stunning story. Its life cycle is easy to observe and study, making it ideal for classrooms and amateur naturalists alike. The monarch is also an object lesson in conservation, as it has been endangered by a once-systematic elimination of its only host plants (milkweeds). Its lookalike, the viceroy, is the classic example of Batesian mimicry. In short, the monarch is a biology and ecology lesson all neatly wrapped in a beautiful package.
The monarch also just so happens to be the only butterfly species I have documented in my garden through all of its life stages. I have also collected its caterpillars to raise. I learned (or possibly relearned?) the term “instar” by way of the butterfly garden, and had the privilege of viewing monarch caterpillars at each of these stages. If you ask me, the caterpillars are almost as attractive as the adults. It’s pretty astonishing to watch them eat and grow so rapidly from the moment they emerge from their eggs as tiny pinheads of life.
Caterpillars, from first to fifth instar
If you want monarchs, all you need do is plant milkweeds (flowers in genus Asclepias). Several species are native and/or do well in the Mid-Atlantic region. I have common milkweed (A. syriaca), butterfly weed (A. tuberosa), swamp milkweed (A. incarnata) and bloodflower (A. curassavica) in my garden. Bloodflower is not native in Maryland, but it grows well here and the monarchs still eat it. Additional milkweeds for your area can be found here. The fact that “weed” is in the name must be what turns folks off, because it really is an attractive plant available in a variety of colors. Milkweeds support a wide variety of other native insects, as well, so they are an excellent choice for anyone desiring to plant natives.
As picky as the caterpillars are, adult monarchs seem to be pretty gregarious feeders. I have seen them take nectar from the milkweeds as a one-stop shop but also from joe-pye weed, butterfly bush, and zinnias. It seems the best strategy for helping monarchs find your milkweed is to plant a variety of perennials and annuals that flower at different times throughout the summer. With the right mix of plants you can expect to see several generations between their mass migrations. If you want to protect them from predators and watch them through a full life cycle, all you really need is a clear, ventilated box or jar, some sticks, and milkweed leaves.