Native trees and shrubs for butterflies and moths: host plants first, nectar second

Plant an oak first, then a wild cherry or plum, then a willow or a birch. Those four genera feed more caterpillar species in the eastern forests than anything else you can put in the ground.

Butterflies and moths need native trees and shrubs as food for their caterpillars far more than as flowers for the adults. A caterpillar can eat only the plants its species evolved with, usually one genus or one family; the adult drinks from almost any flower, or from none. In the eastern forests, oaks are recorded as caterpillar food for 436 species of butterflies and moths, cherries and plums for 340 and willows for 289. About 14 percent of native plant genera feed more than 90 percent of the caterpillar species. Plant the right genera and the moths come, and the birds that eat them follow. Plant only nectar flowers and you feed the adult and nothing before it.

A caterpillar eats one thing, the adult eats almost anything

Some of the pairings are exact:

• The spicebush swallowtail lays its eggs on spicebush and sassafras and on little else; the caterpillar lives in a folded-over leaf and feeds at night.
• The zebra swallowtail uses only pawpaw.
• The giant swallowtail is confined to the citrus family, which in the Northeast means prickly ash and hoptree.
• Five butterflies, the hackberry emperor, the tawny emperor, the American snout, the question mark and the mourning cloak, eat hackberry, and the first three eat nothing else.
• The catalpa sphinx eats only catalpa.

The adults are a different story. The eastern tiger swallowtail caterpillar is limited to wild cherry, tuliptree, sweetbay, basswood, birch, ash, cottonwood, mountain ash and willow; the butterfly takes nectar from cherry, lilac, milkweed, Joe-Pye weed and many other flowers. The emperors feed on sap, rotting fruit, dung and carrion, and the tawny emperor almost never visits a flower. The luna, cecropia, polyphemus, promethea, imperial and rosy maple moths do not feed at all as adults; everything they are was built from leaves eaten as a caterpillar. A butterfly garden made of flowers alone stays empty of moths.

Fourteen percent of the plants feed ninety percent of the species

Douglas Tallamy and Kimberley Shropshire ranked all 1,385 plant genera found in the Mid-Atlantic states by the number of butterfly and moth species recorded eating them as caterpillars. Natives supported more species than introduced plants and native woody ornamentals more than introduced woody ornamentals, all highly significant. A 2020 follow-up across the country found the same shape: on average 14 percent of the local plant genera, the keystone genera, support more than 90 percent of the caterpillar species. In their simulations, 20 woody plants chosen at random supported 38 percent of the local caterpillar species; 20 plants of which half were keystones supported 71 percent.

The keystone genera we grow

For the Eastern Temperate Forests, the ecoregion that includes the Mid-Atlantic, the National Wildlife Federation publishes the counts.

The list is a ranking of what to plant. The last column names what we grow in each genus. If you already have common willows, poplars, maples, pines or elms, keep them. Beyond the keystone genera, five of ours carry specialists or late nectar, with spicebush and pawpaw from the list below:

• For the luna and regal moths, American persimmon.
• For the red-spotted purple and the hummingbird clearwing, Washington hawthorn.
• For Henry’s elfin, nannyberry and blackhaw.
• For the promethea, sweetbay magnolia.
• For late-summer nectar, sweet pepperbush.

The plants that one species cannot live without

The keystone list counts species, not dependence; some of the most striking butterflies and moths of the East hang on one genus far down it.

• Spicebush and sassafras. The spicebush swallowtail and the promethea moth; the promethea also uses tuliptree, sweetbay and white ash.
• Pawpaw. The only food of the zebra swallowtail, which prefers young plants.
• Hackberry. The two emperors and the snout, plus the question mark, which also uses elms, and the mourning cloak, which also uses willows and elms.
• Hoptree and prickly ash. The giant swallowtail.
• Eastern red cedar. The only host of the juniper hairstreak in the East. Its chrysalids lie in the duff under the tree; a limbed-up cedar is useless to it.
• Eastern redbud. Henry’s elfin lays its eggs on the flowers and buds, pupates in the litter at the base of the tree and takes its nectar from the same flowers. In the South it uses American holly; elsewhere huckleberries, blueberries and viburnums.
• Northern catalpa. The catalpa sphinx, whose caterpillars walk down the trunk and dig 2 to 3 inches into the soil to pupate.
• White fringetree and mountain laurel. The laurel sphinx.
• Black locust and indigobush. The silver-spotted skipper, which eats woody legumes.
• Smooth alder, witch hazel, hawthorn and ash. The harvester lays its eggs among the woolly aphids on these plants, and its caterpillars eat the aphids. Spray the aphids and you lose the butterfly.

Bear oak deserves its own line. Edwards’ hairstreak eats scrub oak and occasionally black oak, and its caterpillars hide by day in ant nests at its base. The sleepy duskywing eats scrub oak and other shrubby oaks, and the buck moth eats scrub oak, blackjack oak and dwarf chestnut oak. Our bear oak and dwarf chinquapin oak are those two shrub oaks.

Moths are most of it, and most of the bird food

North America has about 800 species of butterflies and just over 11,000 species of moths, so most of the oak’s 436 species are moths. Nearly all are small and brown, and they are why the trees matter to birds: the National Wildlife Federation puts it that 96 percent of terrestrial birds rely on the insects that keystone plants support. In the Washington, D.C. suburbs, yards with more than about 30 percent nonnative plant biomass could not sustain Carolina chickadees; caterpillars grew scarcer and the birds raised fewer young. The birds article takes that further; for the trees the rule is that caterpillar food is bird food, and a tree with chewed leaves is working.

The caterpillars of five moths eat these trees and shrubs:

• Luna: hickories, walnuts, persimmon, sweetgum, sumacs and birch.
• Regal moth: hickories, pecan, black walnut, sweetgum, persimmon and sumac. Its caterpillar is the hickory horned devil.
• Cecropia: cherry and plum, apple, alder, birch, dogwood, willow and maple.
• Polyphemus: oak, willow, maple and birch.
• Rosy maple moth: maples.

Eggs on twigs, cocoons in leaves, pupae in soil

Almost none of these insects migrate. They spend the winter as an egg, a caterpillar, a chrysalis, a cocoon or a hidden adult, on the tree or within a few feet of it. The banded and striped hairstreaks lay their eggs on oak, hickory and plum twigs in summer. The eggs hatch the next spring. The coral hairstreak’s eggs winter on cherry and plum twigs. The buck moth rings its eggs around an oak twig in the fall. The viceroy winters as a caterpillar inside a rolled leaf tip on the twig, and the emperors in groups inside dead rolled leaves.

The luna spins its cocoon in the leaf litter under the host tree; the buck moth does the same, or goes a few inches into loose soil. Henry’s elfin, the brown elfin and the juniper hairstreak pupate in the litter at the base of the plant. The imperial, rosy maple and regal moths and the catalpa, laurel and wild cherry sphinxes pupate underground. The red-banded hairstreak lays its eggs on the fallen leaves under staghorn sumac and oaks, and its caterpillars eat the fallen leaves. The mourning cloak and the question mark winter as adults, the mourning cloak in the gaps inside brush piles.

“Do not limb up your cedar trees since this renders them useless as hairstreak hosts.” (Alabama Butterfly Atlas, Juniper Hairstreak)

This is why a tidy bed fails these insects even under the right tree. Rake the leaves off in October and the luna cocoons, the elfin chrysalids and the hairstreak’s leaf-borne eggs go to the curb with them. Shred them with a mower and you cut through what is inside; the Xerces Society’s advice is a rake or blower and whole leaves. Cultivate or re-chip the bed in spring and the pupae in the top few inches of soil are crushed or buried.

Leaf litter, not wood chips, is the rule under a tree planted for caterpillars, out to the drip line, and a brush pile gives the mourning cloaks a winter. Put winter prunings from oaks, hickories and plums on the pile, not through the chipper: the eggs on them hatch in spring.

Nectar, sap and rotting fruit from trees and shrubs

The woody plants carry a nectar calendar of their own:

• April and May. Redbud flowers feed Henry’s elfin, Juvenal’s duskywing and the zebra swallowtail; American plum feeds the elfins and duskywings; spicebush feeds the brown elfin; wild cherry feeds the tiger swallowtail.
• June and July. The hairstreaks come off the oaks and hickories to drink at New Jersey tea, staghorn sumac, chinquapin, dogwood and viburnum.
• High summer. Buttonbush, one of the few native shrubs that flowers in midsummer, feeds the silver-spotted skipper, and sweet pepperbush feeds the spicebush swallowtail, the American snout, the question mark and the red-banded hairstreak.

The mourning cloak prefers oak sap; the emperors, the question mark and the red-spotted purple take sap, rotting fruit, dung and carrion. Sapsucker wells are one sap source; fallen persimmons, plums and mulberries are the other half of that diet.

Butterfly bush is the plant most people buy for butterflies, and it is the wrong one. It is from China, and it is listed as invasive in North Carolina. The caterpillars of native butterflies cannot feed on its leaves. Buttonbush, sumac, New Jersey tea and sweet pepperbush do the same nectar job and carry caterpillars as well.

“As the name implies, it attracts butterflies, which feed on its nectar. However, the larvae (caterpillars) of native butterflies cannot feed on its leaves.” (North Carolina State Extension Plant Toolbox, Buddleja davidii)

Cultivars, leaf color and what to avoid

Tallamy’s group tested native cultivars against their wild types across six traits: leaf color, variegation, fall color, habit, disease resistance and fruit size. Cultivars whose leaves had been changed from green to red, blue or purple deterred insect feeding in all three of their experiments. Variegated leaves were preferred in one of them, and the other traits showed no consistent pattern. A green-leaved cultivar selected for habit or disease resistance is probably fine; a dark-leaved one is not food. A seed-grown tree of the straight species carries the leaf chemistry the caterpillars evolved on, which is one reason Blue Whale Trees grows everything from seed.

Nonnative trees and shrubs are the larger loss. Tallamy and Shropshire found that introduced woody plants, invasive and ornamental alike, support significantly fewer caterpillar species than natives. A yard of Japanese maple, crape myrtle and Bradford pear therefore feeds a fraction of the moths a yard of natives does. At forest scale, the invasive shrubs and vines that follow them into the woods do the same.

Pesticides: Bt, mosquito sprays and treated nursery stock

Three products undo the planting:

• Bt (Bacillus thuringiensis var. kurstaki), sold as an organic caterpillar killer. It kills the caterpillars that eat treated leaves and cannot tell a swallowtail from a cabbage worm, so keep it away from host plants.
• The residential mosquito spray. In a 2025 study of yards in Georgia, Iowa and Massachusetts, every yard sprayed by a private mosquito company carried pyrethroid residues. The residues were high enough to kill bees and other beneficial insects, on average more than six times the honey bee’s lethal dose. Of the neighboring yards, 75 percent were contaminated too.
• The systemic insecticide already inside a plant when you buy it. Nursery stock and landscape trees are commonly treated with neonicotinoids and related systemics; the chemical moves into leaves, flowers and fruit, and it has been detected inside woody plants years after application. Ask any nursery whether a tree was treated.

“Do not use Bt (Bacillus thuringiensis ssp. kurstaki) in a butterfly garden where you wish to have caterpillars because this strain of Bt kills caterpillars.” (University of Wisconsin Horticulture Extension, Create a Butterfly Garden)

The hosts we added with this article, and the ones we still do not sell

The plants that were missing from the catalog when this article was researched are in it now, because the caterpillar records made the case:

• Hackberry, which carries five butterflies and is rarely offered in the Mid-Atlantic.
• Sassafras, the spicebush swallowtail’s second plant and the promethea’s, seldom sold because of its taproot.
• Hoptree and prickly ash, the giant swallowtail’s only native woody hosts in the Northeast.
• New Jersey tea, which feeds the azures and the mottled duskywing as caterpillars and the hairstreaks as adults.
• Sweet birch and deerberry, which came in for the birch and blueberry counts, 284 and 217.

What a yard often lacks matters as much. Black cherry is the tree behind most of the Prunus count. It is a host of the tiger swallowtail, the red-spotted purple, the coral hairstreak, the cecropia and the promethea. Almost no garden center sells it. Tuliptree is the only food of the tuliptree silkmoth. Willows and poplars are the third and fifth keystone genera, and maples, pines and elms all sit inside the top twelve. If you have any of these already, keep them; the wild cherry in the fencerow is worth more to moths than most things you could plant in its place.

Where to start

1. Plant an oak. On a small lot, plant bear oak or dwarf chinquapin oak.
2. Add one plant from the cherry, hickory, alder or walnut lists and one specialist plant: spicebush, pawpaw or redbud.
3. Leave the leaves under every tree and shrub out to the drip line, whole, and never cultivate or re-chip that ground in spring.
4. Build a brush pile and put winter prunings on it.
5. Keep a midsummer nectar shrub, buttonbush or sweet pepperbush, near the host plants.
6. Buy seed-grown plants with green leaves, and ask whether they were treated with a systemic insecticide.
7. Cancel the mosquito service, keep Bt off the host plants and leave the aphids on the alder alone.
8. Expect chewed leaves. A native tree loses some foliage to caterpillars every year and grows anyway; that share is the point.
9. Put the seven plants these steps name on a request list, keep the ones you choose, and we reply with what is ready and current pricing.

Common questions

Which native tree hosts the most butterflies and moths?

Oaks, with 436 species of caterpillar recorded on them in the eastern forests, then the cherries and plums at 340 and the willows at 289. Plant an oak first.

Should I plant butterfly bush for butterflies?

No: it is from China, listed as invasive in North Carolina, and no native caterpillar can eat its leaves. Buttonbush, sumac, New Jersey tea and sweet pepperbush feed the adults and carry caterpillars too.

Do I have to leave the leaves under the trees?

Yes, whole and out to the drip line, because luna cocoons, elfin chrysalids and hairstreak eggs spend the winter in them. Raking or shredding sends next year’s insects to the curb.

Do any trees feed monarch caterpillars?

No: monarch caterpillars feed only on milkweed leaves, so no tree is their host. The adults take nectar from many flowers but breed only where milkweeds grow.