Variegated fritillary on Echinacea purpurea.
Attract butterflies with flowers and larval host plants
It is given that butterflies + flowers + sunny summer days = pure joy.
These are the days of summer when the air begins to fill with the flitting, fluttering, fairy wings of many beautiful butterflies. The flowers in our gardens draw butterflies and other insects in with their bright colors and nutritious nectar. Butterfly gardening has a long tradition among gardeners around the world. More recently, gardeners have begun to realize that they need to provide not only nectaries, but also host plants for their favorite lepidoptera.
Many insects co-evolved with certain plants or plant families. Over thousands or millions of years of evolution, plants have developed special toxic chemicals to defend their leaves from being eaten, but certain insects have in turn evolved an immunity to the particular chemicals in their favorite leaves. Thus, the plants and the insects become partners of sorts. A plant that sustains a particular butterfly species is called its larval host, because it is in the larval, or caterpillar, stage when leaves are consumed for sustenance. Once a butterfly larva enters its chrysalis (pupal stage), it no longer eats leaves. And when it emerges as an adult butterfly, it becomes a nectar feeder, dependent upon flowers for food. Adult butterflies are not as choosy when it comes to nectar sources, although some do demonstrate preferences for certain kinds of flowers.
Thus, in order to increase the number of butterflies in the world - and who doesn't want that? - we must assure the presence of both larval host plants and nectar plants.
Larval host plants: generalists and specialists
Many plants play host to a number of different butterfly and moth larvae. Oak trees (Quercus spp.) boast the widest range of larval feeders, at 557, according to Doug Tallamy, an entomologist at the University of Delaware and author of the excellent book Bringing Nature Home: How You Can Sustain Wildlife with Native Plants
Black locust - Robinia pseudoacacia.
Meanwhile, other species such as the zebra swallowtail, only feed upon the leaves of the pawpaw (Asimina triloba):
Zebra swallowtail caterpillar on a pawpaw leaf.
So, if you want a big bang for your plant buck, look for plants that host a large number of lepidoptera species. If you really want to draw a particular species in, such as the zebra swallowtail, then you'll need to plant a pawpaw tree.
More butterflies and their hosts
Here is a table with some common butterflies to the Mid-Atlantic region and their larval host plants. It's not by any means complete - just represents some of the species I've been able to snap photos of in recent weeks:
[Also, I am still learning butterflies. While I believe I have correctly identified the photos below, please let me know if you spot any errors! I welcome corrections.]
Adult (Click to enlarge)
Larval Host Plant(s)*Favorite Nectar Sources**American Lady
Pearly everlastings (Anaphalis spp.) and other composites.Burdock, daisy, everlastings, Mallow, Yarrow, Zinnia, HeliotropeCabbage White
Brassicaceae species (broccoli, cauliflower, cabbage, and many other garden and wild species)Generalist - drinks nectar from many garden and wild flowers.Eastern-Tailed Blue
Fabaceae species (pea family: vetch, clover, locust, lupines, etc.)Daisy, dandelion, clovers, milkweedEastern Tiger Swallowtail
Black cherry (Prunus serotina) and Tulip poplar (Liriodendron tulipifera)Bee Balm (Monarda), butterfly bush, honeysuckle, sunflower, Mexican sunflower (Tithonia)Horace's Duskywing
Oaks (Quercus spp.)Lavender, boneset, buttonbush, dogbane, goldenrodLittle Wood-Satyr
Milkweeds (Asclepias spp.)Milkweed, asters, red clover, zinnia, cosmos, lantana, pentas, daisy, Mexican sunflower (Tithonia)Orange Sulphur
Fabaceae species (pea family: vetch, clover, locust, lupines, etc.)Clovers, dandelion, parsley, zinnia, other meadow flowers, composite familyPearl Crescent
AstersZinnia, daisies, clovers, goldenrodQuestion Mark
Nettles, elm family, hackberry, and othersRotting fruit, dung, meadow flowersRed-Spotted Purple
Cherry (Prunus spp.) and othersRotting fruit, dung, small white flowers such as a white BuddleiaSilver-Spotted Skipper
Black locust (Robinia pseudoacacia) and other Fabaceae (pea family) speciesBlazing stars, buttonbush, common milkweedSkipper (species unknown - ideas? There are many, many skippers)
GrassesButtonbush, milkweeds, vetchGreat Spangled Fritillary
Violets (Viola spp.)
Milkweed, New England aster, red clover, zinnia, cosmos, lantana, pentas, daisy
*Larval host plants from Butterflies Through Binoculars: The East, by Jeffrey Glassberg.
** Nectar sources from https://www.joyfulbutterfly.com/what-do-butterflies-eat/. These are not exhaustive lists - butterflies may drink from numerous flower species.
Get out butterflying
I've begun to pay more attention to butterflies thanks to my friend Mary Helen, who has turned me on to butterflying. We go out with binoculars, field guides, and cameras to search out butterflies in various habitats, from fields to wetlands to forests. It's quite exciting to learn about a new species, discover what its host plant is, look for the plants, and then spot a larva or adult butterfly. Like magic!
Once you start learning more, you appreciate the connection between the plants in a given habitat and the associated fauna. You will be hooked! One thing that can really help is to use special close-focusing binoculars, which let you minutely examine a butterfly's markings from as close as about 6 feet away, to high up on a tree. The North American Butterfly Association (NABA) has a very helpful page on their website describing the characteristics of various binoculars and a handy comparison table to get you started.
With the information above, you are ready to get started creating your own butterfly-friendly landscape. Be sure to include both larval host plants and nectar sources for your butterflies, and soon your garden will abound with these jewels of the air.
Here are some helpful links which provide lots of useful information:
A Swift Guide to Butterflies of North America: Second Edition
Butterflies through Binoculars: The East A Field Guide to the Butterflies of Eastern North America
Butterflies of Delmarva