Welcome to part II, butterfly larval food sources. Seeing butterflies in the garden always feels like I've been given a front row seat to watch a very special dance performance. As discussed previously, all flowering plants provide nectar that adult butterflies feed on so if you have any flowers in your garden, you are likely to see butterflies. But caterpillars, the larval stage of butterflies, have strict dietary requirements. Therefore, in order to sustain future generations of butterflies, we need to know which specific plants serve as hosts to their caterpillars.
It must have been an enormous effort to collect all this information about caterpillar host plants into a searchable database, but I sure am grateful for it. While this is a nation-wide list of plants that support butterflies, the sidebar navigation makes it super easy to restrict the list by state, by type of plant (trees or herbs or vines), and/or by preferred growing conditions.
In the above video, the conservationist states that trees are important larval food sources for butterflies. So if you have the space, plant native trees. This is also the central argument of Bringing Nature Home by Douglas Tallamy, that trees do the most for wildlife by providing food and shelter and that native plants do the most for native bugs because of relationships established through co-evolution. Specific to butterflies, Tallamy has tallied which mid-Atlantic native trees support the most butterfly species...and it's astounding. For example, native Quercus species (oak trees) have been observed to support more than 500 butterfly species!
If you live in DC and your yard is large enough tor trees, I highly recommend contacting Casey Trees. For just $50 per tree, a professional arborist will help you to select the right tree for your yard and plant it for you. Nearly all of the trees offered through the residential planting program are natives including Northern Red Oak, American Beech, Red Maple, and Virginia Pine. If you prefer the DIY route, the Arbor Day Foundation will send you 10 bare-root seedling trees for $10. And now I know what I'm getting all my friends and family for their birthdays this year: 10 trees planted where they're needed most in our National forests.
Since I don't have enough space for trees in my own garden, I'm sticking to smaller native shrubs and herbaceous perennials. I'm planting New Jersey tea in my shaded front yard...I've read differing opinions about its shade tolerance, but its fluffy cloud-like flowers and the fact that it hosts three species of caterpillars made me want to give it a try. If it doesn't work out, there are several other native shrub alternatives to the potentially invasive butterflybush such as viburnum, spicebush, sumac, spirea, and hydrangea.
Most gardeners already know about milkweed for Monarchs. Other important natives include grasses such as little bluestem and switchgrass as well as New England and smooth blue asters. Edible plants also make the list: fruiting trees such as pawpaw, persimmon, and black cherry; grape, passion fruit, and hop vines; blueberry bushes; and violas and culinary herbs in the carrot family (dill, cilantro, parsley, fennel...) are all larva food sources for butterflies.
Many public gardens feature butterfly gardens and educational programs about butterflies. In DC, among our many public garden resources, we have the Natural History Museum's Butterfly Pavilion.