- Aug 6, 2019

Planting for Butterflies: Larval Hosts and Nectar Sources

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

. Some insect species can also eat the leaves of a range of plant species, but often within the same family. For example, the larvae of silver-spotted skippers like this one feed on black locust (Robinia pseudoacacia) and many other members of the Fabiaceae (legume) family.

Silver-spotted skipper.

Black locust - Robinia pseudoacacia.

Meanwhile, other species such as the zebra swallowtail, only feed upon the leaves of the pawpaw (Asimina triloba):

Zebra swallowtail.

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.]

Butterfly Species

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

GrassesTree sapMonarch

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

Zebra Swallowtail

Photo credit: Mary Helen GillenPawpaw (Asimina triloba)Milkweed, Joe-pye weed, 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.

Get planting

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:

North American Butterfly Association (NABA)

The Xerces Society

Monarch Watch

Guide books:

A Swift Guide to Butterflies of North America: Second Edition

, by Jeffrey Glassberg - this is a wonderful book and includes a very useful visual index at the back, so you can quickly find the likely species without having to page through every single photo plate.

Butterflies through Binoculars: The East A Field Guide to the Butterflies of Eastern North America

, by Jeffrey Glassberg - a classic guide with lots of great information about habitats, host plants, geographic ranges, identification hints, and separate photo plates with range maps.

Butterflies of Delmarva